Research ArticleNutrient Release Pattern and Greenhouse-Grown Swiss ChardResponse to Biochar Inoculated with Vermicast
Lord Abbey 1 Jinsheng Cai 1 Lokanadha R Gunupuru 1 Mercy Ijenyo 1
Ebenezer O Esan 2 and Suwen Lin 1
1Department of Plant Food and Environmental Sciences Dalhousie University Faculty of Agriculture 50 Pictou RoadPO Box 550 Truro B2N 5E3 Nova Scotia Canada2)e University of Western Ontario Department of Biology 1151 Richmond Street London N6A 3K7 ON Canada
Correspondence should be addressed to Lord Abbey loab07gmailcom
Received 7 March 2020 Accepted 27 March 2020 Published 14 April 2020
Academic Editor Maria Serrano
Copyright copy 2020 Lord Abbey et al is is an open access article distributed under the Creative Commons Attribution Licensewhich permits unrestricted use distribution and reproduction in any medium provided the original work is properly cited
A study was performed to assess nutrient release from biochar inoculated with solid vermicast (SVB) vermicast tea (VTB)deionized water (DWB) uninoculated biochar (Bioc) and Promix-BX (Pro-BX) e growth response of Swiss chard (Betavulgaris subsp vulgaris) cv Rhubarb chard was also assessed Comparatively nutrients were released slowly from treatments SVBand VTB compared to the other treatments e rate of nutrient release determined by total dissolved solids and electricconductivity from the Pro-BX was the highest e trend for the plant growth components total leaf surface area and leaf freshweight at first harvest was Pro-BXgtBiocgtDWB SVBgtVTB e only treatment that increased total leaf area and leaf freshweight at the second harvest by approximately 102- and 188-fold was VTB Leaf fresh weight was significantly reduced byapproximately 033-fold for DWB 028-fold for Bioc and 070-fold for Pro-BX but was not altered by SVB at the second harvest ascompared to the first harvest A 2-dimensional principal component analysis (PCA) biplot confirmed that treatment Pro-BXincreased plant growth components at the first harvest only e locations of SVB and VTB on the PCA biplot confirmed theirefficacies which led to increases in the plant growth components at the second harvest Overall the VTB adsorbed more nutrientsonto its surface that were slowly released to enhance the Swiss chard cv Rhubarb chard plant growth at the second harvest Furtherstudies should consider microbial activities
1 Introduction
Globally more research is being focused on climate-smartagricultural technologies and sustainable food production inorder to meet the current and future food and dietary de-mands [1ndash3] As such most farmers adopt intensive use ofsynthetic chemical fertilizers which can be detrimental tothe environment ecological system and the health of lifeforms e use of organic amendments such as vermicastand biochar for both field and controlled-environmentproduction is professed as sustainable clean technology
Grewal et al [4] reviewed that biochar is obtained fromthermochemical conversion of biomass in an oxygen-limitedenvironment by the process of pyrolysis Many studies haveshown that biochar can enhance the biological physical and
chemical properties of growing media ese include im-provements in soil structure slow release of nutrients se-questration of carbon cation exchange capacity sorptioncapacity water-holding capacity and soil fertility [5 6]However it is worth noting that the nature and type ofbiomass and the method of the pyrolytic process such astemperature used can influence the physical and chemicalproperties of the biochar and its efficacy ese properties ofbiochar have drawn the attention of many researchersenvironmentalists and farmers leading to increased use inthe environmental and agricultural sectors worldwide Es-sentially the benefit of biochar is dependent on the rate ofbiochar application the properties of the growing mediumand the genotypic characteristics of the plant [7] Biocharability to support plant growth is determined by the
HindawiInternational Journal of AgronomyVolume 2020 Article ID 7852187 9 pageshttpsdoiorg10115520207852187
surrounding growing medium chemistry that it interactswith According to Rees et al [7] the chemical status of soilcan influence the efficacy of biochar
Inoculation of biochar using organic amendment orsynthetic chemical fertilizer triggers its adsorptive surfacewith abundant nutrients in addition to the creation of op-timal microenvironment for microbial growth and increasedwater storage capacity [7ndash10] Ultimately the functionalityof the growing medium is enhanced However the previousstudy showed that by virtue of the high pH biochar canimmobilize major nutrients such as calcium nitrate-nitro-gen and phosphorus [7] is can be a major problem whenusing biochar since these nutrients may become unavailableto plants Also such immobilization activity can influencethe pattern of nutrient release to plants Furthermore theactivities of microbial communities as well as other physicalcharacteristics such as water availability and the structure ofthe growing medium can also influence the release andavailability of nutrients to plants It is therefore hypothesizedthat intentional inoculation of biochar can circumvent thesepotential problems related to nutrient release and plantuptake Materials that can be used to inoculate biocharinclude vermicast thermophilic compost biosolids animalmanure and liquid fertilizer [3] Despite this knowledge thepattern of nutrient release from inoculated biochar usingnatural amendments such as vermicast with respect to timeof application is not well understood is is the main thrustof the current study
Vermicast is rich in microorganisms and plant growth-promoting chemical compounds derived from humic andnonhumic substances which include mineral nutrientsorganic acids nucleic acids macromolecules and antimi-crobial and pesticidal compounds [11] It is therefore ex-pected that the characteristic effect of vermicast-inoculatedbiochar will be significantly higher than if it was not in-oculated as explained by Beesley et al [9] And although thenutrient release rate of the inoculated biochar is expected tobe low it is hypothesized that the synergetic benefits derivedfrom the combination of biochar and vermicast throughinoculation and incubation procedures will be highly effi-cacious e effect of residual nutrients from inoculatedbiochar on plant growth also needs to be investigatederefore the objective of the study was to assess andcompare the nutrient release pattern of solid vermicast-inoculated biochar vermicast tea-inoculated biochar andbiochar alone and their residual effects on plant growth etest plant was Swiss chard (Beta vulgaris subsp vulgaris cvRhubarb chard) which was chosen for its ease of productionduring the cool weather in fall and winter and its ability towithstand sequential harvesting required for the assessmentof plant response to growing medium nutrient residue
2 Materials and Methods
21 Location andMaterials e study was carried out in theCompost and Biostimulant Laboratory and the researchgreenhouse located in the Department of Plant Food andEnvironmental Sciences Dalhousie University Faculty ofAgriculture fromApril to December 2017e biochar from
white pine (Pinus strobus) was produced through pyrolysisat 11000degC and was obtained from Proton Power Inc TNUSA vermicast from red wiggler (Eisenia fetida) was pur-chased from Co-op Country Store Truro NS CanadaPromix-BXtrade (Premier Horticulture Inc QuakertownUSA) a general-purpose peat-based substrate consisted of75ndash85 sphagnum peat moss horticultural-grade perliteand vermiculite chemical fertilizer dolomitic and calciticlimestone a wetting agent and mycorrhizal fungus (Glomusintraradices) was purchased from Halifax Seed Inc HalifaxNS Canada Seeds of Swiss chard (Beta vulgaris subspvulgaris cv Rhubarb chard) was also purchased fromHalifaxSeed Inc
22 Biochar Inoculation and Chemical Analysis e biocharwas inoculated with solid vermicast at 45 moisture con-tent vermicast tea and distilled water alone for 40 days evermicast tea was made by adding a liter of distilled water to100 g of solid vermicast and stirred at 1200 rpm for 24 hrusing DLM1886X1 Isotemp stirring plate (Fisher ScientificInc Markham ON Canada) e biochar was then inoc-ulated with the vermicast tea (VTB) by thoroughly mixing500 g of solid dry biochar and one liter of the vermicast teaprior to incubation e solid vermicast-inoculated biochar(SVB) was made by thoroughly mixing 500 g of the solid drybiochar and 100 g of the solid vermicast prior to incubatione deionized water-inoculated biochar (DWB) was madeby thoroughly mixing 500 g of the dry biochar and one literof deionized water prior to incubation e individualmixtures were then incubated for 40 days in the dark at roomtemperature (ca 21degC) and relative humidity conditionsecontrol treatments were 500 g of the dry biochar alone and500 g of Promix-BX potting mix alone also incubated underthe same room conditions All the treatments were intriplicate Samples (100 g) of each of the growing mediumsubstrates were sent to the Nova Scotia Department ofAgriculture (NSDA) Laboratory Services Truro NS fornutrient analysis Total nitrogen (N) was determined by theAOAC-99003 combustion method [12] using a LECO-SpecAnalyzer (TruSpecreg Micro LECO MI) while calcium (Ca)potassium (K) phosphorus (P) magnesium (Mg) sodium(Na) boron (B) copper (Cu) iron (Fe) manganese (Mn)and zinc (Zn) were determined using the AOAC-96808inductively coupled plasma (ICP) spectrometermethod [13]
23 Nutrient Release and Electrochemical Analysis A nu-trient release study was performed in the laboratory using acylindrical glass jar measuring 35 cm in height and 10 cm forthe inner diameter Each glass jar was filled with one liter ofdeionized water and the dissolved matter and releasednutrients in solution were determined using the methoddescribed by Abbey et al [14] with slight modification Inbrief 20 g of each of the five growing medium treatmentswas placed separately in a HEPA filter grade Rosin Technylon press bag (Rosin Tech Products CA USA) with amesh size of 25 μm and a dimension of 635 cmtimes 1016 cme individual samples were submerged in the deionizedwater in the glass jar 20ml samples of the solution from the
2 International Journal of Agronomy
individual glass jars were collected with replacement every10min for 1 hr every 30min for 2 hr every 1 hr for 5 hrevery 2 hr for 6 hr every 5 hr for 10 hr and every 24 hr for 24days Oakton PC Tester 35 multimeter (Oakton InstrumentsIL USA) was then used to record the pH total dissolvedsolids electric conductivity and salinity of the solutionscollected before pouring them back into the glass jarLAQUA Twin ion meter (HORIBA Minami-ku KyotoJapan) was also used to measure calcium (Ca2+) nitrate(NOminus3) sodium (Na+) and potassium (K+) ion concen-trations of each collected sample per treatment
24 Greenhouse Experiment A pot experiment was per-formed in the departmentrsquos greenhouse at an averagetemperature of 28degC16degC (daynight cycle) and relativehumidity of 76 Supplemental lighting was provided by a600 W HS2000 high-pressure sodium lamps withNAH600579 ballast (PL Light Systems Beamsville ONCanada) at 12 hr light cycle between November and De-cember when days got shorter or on cloudy days Plastic pots(1524 cm diameter) were filled to the same volume of amixture of the individual components as shown in Table 1e variation in weight was due to the differences in bulkdensity (data not presented) e weight of the uninoculateddry biochar prior to inoculation was 200 g Each treatmenthad four potted plants placed in saucers per replication andthey were replicated four times to give a total of 80 ex-perimental units Each pot was planted with one seedling ofSwiss chard and watered with approximately 200ml of tapwater (based on previous work) every two to three daysdepending on the weather conditions By this methodnutrient loss through leachate was avoided
25 Plant GrowthAnalysis Plant height was measured fromthe stem collar to the tip of the longest leaf using a 30 cmruler at first harvest which was four weeks after trans-planting e other growth measurements were stem di-ameter which was measured from the middle portion of thestem using a pair of Mastercraft calipers (Canadian TireToronto ON Canada) total plant fresh weight was recordedprior to total dry weight determination by drying thesamples in an 52100-10 Cole-Parmer mechanical convectionoven dryer (Cole-Parmer Instrumental Company VernonHills Ill USA) at 65degC for 24 hr plant mass density wasdetermined from the dry weights according to the method ofLouw-Gaume et al [15] e number of edible leaves pertreatment was also recorded at first harvest e twoyoungest leaves on each plant were left for the plants toregrow for a second harvest at eight weeks after trans-planting e weights of the harvested leaves were recordedusing an electronic MXX-412 Denver precision balance(Denver Instrument Company CO USA)e total leaf areawas determined using a LI-3100 Leaf Area Meter (Li-CorInc Lincoln NE USA) Measurements of plant height stemdiameter and leaf area were performed again at the secondharvest (ie 8 weeks after transplanting) for comparisonwith those recorded at the first harvest (ie 4 weeks aftertransplanting)
26 Leaf Tissue Pigmentation and Nutrient Analysis Leafgreenness was used to estimate leaf chlorophyll contentusing a 502 SPAD meter (Spectrum Technologies IncAurora Ill USA) Anthocyanin content was estimated usinga portable ACM200+ anthocyanin content meter (Opti-Sciences Inc Hudson NY USA) Chlorophyll fluorescenceindices were used to determine plant stress level usingportable OS30p +Chlorophyll Fluorometer (Opti-SciencesInc Hudson NY USA) e Chlorophyll Fluorometercalculated the maximum quantum yield or efficiency ofphotosystem II as follows
FvFm
Fm minus Fo
Fm1113876 1113877 (1)
where Fo is the minimum fluorescence Fm is the maximumfluorescence and Fv is the variable fluorescence indices [16]
e Swiss chard leaf greenness anthocyanin contentand chlorophyll fluorescence indices were all recorded fromthe 3rd and 4th leaves of each plant per treatment Samples ofplant leaf tissues were also sent to the NSDA LaboratoryServices for nutrient analysis e leaf samples were washedwith distilled water air-dried and then packed in paper bagsbefore sending for nutrients analyses In brief the plant leafsamples were oven-dried at 60degC for 48 hr and ground intopowder Total N Ca K P Mg Na B Cu Fe Mn and Znwere determined using methods described in [12 13]
27 Experimental Design and Statistical Analysis e ex-periment was arranged in a complete randomized designwith four replications for the greenhouse experiment butthree replications for the nutrient release experiment Forthe greenhouse pot experiment each of the five treatmentshad four samples of plants and a total of 16 potted plants pertreatment Data on leaf greenness and anthocyanin contentplant height stem diameter and leaf area were analyzed byone-way analyses of variance (ANOVA) using SAS version94 software (SAS Institute Inc Cary NC USA) Wheneverthe ANOVA indicated a significant difference ie Ple 005Fisherrsquos protected least significant difference (LSD) at α 5was used to separate the means Graphs of pH total dis-solved solids electrical conductivity salinity calcium ni-trate sodium and potassium were plotted for the nutrientrelease experiment using Microsoft Excel A biplot ofprincipal component analysis was performed to determinethe association between the growing media treatments andthe plant growth components of the Swiss chard cv Rhubarbchard using XLSTAT version 191
3 Results and Discussion
Considerable variations were found in the composition ofnutrients in the individual growing medium componentsie the solid vermicast-inoculated biochar (SVB) vermicasttea-inoculated biochar (VTB) deionized water-inoculatedbiochar (DWB) biochar alone (Bioc) and the Promix-BX(Pro-BX) alone (Table 2)e SVB had higher amounts of NP Na B and Zn as compared to all the other biochartreatments except the VTB treatment which had
International Journal of Agronomy 3
comparable amounts of N K Mg and Na However themanufacturerrsquos premixed medium Promix-BX (Pro-BX)with synthetic chemical fertilizer had the highest amounts ofCa Mg and Cu and a similar amount of N as found in theSVB and the VTB e uninoculated biochar (Bioc) that wasused in this study and the DWB had the highest amounts ofMn and Fe respectively but these two treatments containedthe least amounts of all the other remaining nutrients
e richness in nutrients of the two types of vermicast-inoculated biochar (ie SVB andVTB) compared to the Biocand the DWB was expected Cocomposting or combinationof biochar and natural amendments was reported to increasebiochar nutrient adsorption and overall growing mediumfertility status [9 10 17] Typically vermicast is valued for itsrichness and diversity in humic and nonhumic substancesincluding macro- and micronutrients and other plantgrowth factors [11] ese vermicast chemicals can alter theproperties of biochar when combined or cocompostedBased on the reports by Pietikainen et al [8] and Sizmuret al [18] we can fairly suggest that the biochar inoculatedwith the dry solid vermicast (SVB) or the vermicast tea(VTB) became activated with ionized nutrients that en-hanced the functionality of the biochar is assertion willhave to be verified in future studies
e nutrient release experiment showed that initial wateractivity prior to the dissolution of soluble materials such assurface wetting followed by water imbibition by the particlesconstituting the mixed media led to a lag phase within thefirst few hours when they were submerged in the deionizedwater (Figures 1(a)ndash1(d)) Consequently changes in pHtotal dissolved solids (TDS) salinity and electric conduc-tivity (EC) were initially slow before rapidly increasingcontinuously up to the 100th hour (ca 4th day) beforeslowing down to the end of the experiment on the 495th hour(ca day 21) e high positive correlation exiting betweenEC and total nutrient concentration allows for its use toestimate growing medium fertility status [19] Compared toall the other indices the trend for the changes in pH of thesolutions for all the treatments was different (Figure 1(a))
e pH of the solution rapidly declined within the first40min before steeply rising to reach a peak at the 8th hourfollowed by a steep fall at the 24th hour Overall there wereno clear differences in salinity TDS pH and EC of thesolutions for the SVB VTB DWB and the Bioc apart fromthe obvious fluctuations in the line graph for treatmentDWB According to Sizmur et al [18] the manifestation ofchemical sorption is attributed to ion exchange and nu-merous functional groups on the carbonaceous surface ofbiochar As such the fluctuations in the line graphs for theDWB in Figures 1(a)ndash1(d) can be ascribed to low chemical
activity in the deionized water as compared to the vermicast-inoculated biochar treatments e values of all the mea-sured water quality indices for the Pro-BX treatment werefound to be higher than the respective values for SVB VTBDWB and Bioc treatments However the differences beganto show after the 300th hour ese findings demonstratedthe slow release of nutrients from the biochar treatmentscompared to the Pro-BX Particularly the DWB seemed tobe the fastest in releasing its nutrients while the SVB and theBioc seemed to be intermediate It was noticed that therelease of materials into the solution and the pH fortreatment Pro-BX seemed to be generally more stable afterthe 350th hour of sampling compared to the othertreatments
e release of nitrate (NO3minus) into the deionized waterfrom the Pro-BX treatment was the fastest compared to allthe biochar treatments and was followed by a steep declineimmediately after 2 hr of submergence (Figure 2(a)) Afterthe 150th hour the amount of NO3minus released into the so-lution from the Pro-BX did not change However NO3minus
released into solution from the SVB DWB VTB and theBioc showed significant fluctuations throughout the sam-pling period which lasted for 591 hr (ca 246 days) efluctuations can be attributed to microbial and chemicalactivities such as bioconversion of N anion exchange andvolatilization but were not determined in the present studyA lag phase prior to the first 50th hour followed by a rapidincrease in ionic concentrations of K+ Na+ and Ca+2 in thesampled solution (Figures 2(b)ndash2(d)) was also observed econcentrations of K+ and Na+ in the sampled solutions fromall the treatments increased exponentially while that of the
Table 2 Mineral nutrient composition of the growing mediacomponents
Ca2+ seemed to have increased linearly as sampling timeprogressed Amongst the biochar treatments the highest K+
concentration was recorded by the DWB treatment and theleast was recorded by the Bioc treatment while the SVB andthe VTB treatments were in between and not different
Comparatively the release of K+ and Na+ into solutionfrom the Pro-BX was instant and consistently the least justlike the NO3minus is can be attributed to the highly solublenature of K and Na salts However the release of Na+ intosolution was not different amongst the four biochar treat-ments On the contrary the release of Ca2+ into solutionfrom the Pro-BX treatment was the fastest and the highestand was represented by a sigmoidal curve in Figure 2(c) eresult showed that the release of Ca2+ from the Pro-BXsteeply rose after the 100th hour of sampling before levellingoff Overall Ca2+ concentration of all the four biochartreatments fluctuatede release of Ca2+ was highest for theBioc treatment followed by the SVB then the DWB and the
VTB (Figure 2(c)) e fluctuations in the concentrations ofCa2+ released into solution from the biochar treatmentscould be ascribed to ionic exchange activities on the car-bonaceous surface of the biochar erefore the presentresults can be explained by possible modification and ac-tivation of the biochar when it was inoculated with vermicastor deionized water followed by an incubation period asreported by Sizmur et al [18] From Figures 2(a)ndash2(d) itseemed the concentrations of NO3minus K+ Ca2+ and Na+ fromeach of the biochar treatments will continue to rise if thesampling time was extended beyond the 591 hr of the nu-trient release study e variation in the trend of nutrientrelease from the different media treatments is an indicationof possible variations in nutrient availability for plant uptakeand utilization for growth and development
Chlorophyll fluorescence activity was used to assessphotosynthetic activities in Swiss chard cv Rhubarb chardgrown in different treatments It was found that the
Figure 1 Changes in pH total dissolved solids salinity and electric conductivity of solid vermicast-inoculated biochar (solid line greensquare) vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biocharalone (solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard errorbars
International Journal of Agronomy 5
maximum quantum yields also termed as efficiency ofphotosystem II (FvFm) for the Swiss chard plants rangedbetween 076 and 078 and were not significantly (Pgt 005)different between treatments (data not presented) Leafchlorophyll content estimated using the SPAD value of leafgreenness was differentially influenced by the differentmedium treatments Prior to the first harvest ie four weeksafter transplanting the SPAD value was significantly highestin plants grown in the treatment Pro-BX followed bytreatments SVB and VTB and lowest in treatments Bioc andDWB (Figure 3(a))
However there was a remarkable change in the extent towhich the treatments affected the SPAD value of leafgreenness at the second harvest at eight weeks after trans-planting Treatments SVB and VTB equally increased SPADvalue at the second harvest by ca 044-fold compared to thefirst harvest but was remarkably reduced in plants grown inthe Pro-BX by ca 038-fold It was noted that the change washowever moderate in Swiss chard plants grown in the DWBand the Bioc Leaf anthocyanin content was similar for all theplants irrespective of the medium treatment at the firstharvest (Figure 3(b)) At the second harvest only treatmentsVTB and SVB increased leaf anthocyanin contents by ca080- and 095-fold respectively ese findings indicatedthat leaf pigmentation was significantly influenced by VTB
and SVB compared to the other treatments is furtherconfirmed the slow release of nutrients from biochar in-oculated with vermicast
e number of Swiss chard green leaves and plant massdensity which indicate assimilate accumulation were notsignificantly (Pgt 005) different among the treatments andbetween the two harvest times (data not presented) How-ever other plant growth components such as plant heightstem diameter leaf fresh weight and total leaf area wereclearly affected (Figures 4(a)ndash4(d)) ese plant growthcomponents were significantly (Plt 005) increased bytreatment Pro-BX followed by treatments DWB and Biocand the lowest by treatments SVB and VTB at the firstharvest But this growth trend changed at the second harvest
Changes in plant height between the first and the secondharvests were prominent for VTB and SVB It was found thatplant height increased by approximately 203-fold for VTBand by 067-fold for SVB and did not significantly (Pgt 005)change for Bioc or DWB but significantly (Plt 005) reducedby ca 045-fold for Pro-BX Swiss chard plant stem diameterwas increased by approximately 166-fold for VTB and 059-fold for SVB while minor nonsignificant changes wererecorded for Bioc and DWBe Pro-BX on the other handsignificantly (Plt 005) reduced stem diameter by ca 047-fold at the second harvest e trend for both total leaf
Figure 2 Release of potassium sodium nitrate and calcium contents of solid vermicast-inoculated biochar (solid line green square)vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biochar alone(solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard error bars
6 International Journal of Agronomy
b bc bc
aC
C
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
50
100
150
200
250
Plan
t hei
ght (
cm)
PH1PH2
(a)
bcb
c c
a
BCBC
B
A
C
Bioc DWB SVB VTB Pro-BXTreatments
00
20
40
60
80
100
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dia
met
er (m
m)
SD1SD2
(b)
b b bc
a
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l lea
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eigh
t (g
plan
t)
Treatments
00
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(c)
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cd
a
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n le
af ar
ea (c
m2 )
LA1LA2
(d)
Figure 4 Plant height (PH) stem diameter (SD) leaf area (LA) and total edible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculatedbiochar (SVB) vermicast tea-inoculated biochar (VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical lettersrepresent mean separation by the least significant difference (α 005) at the first (1) and the second (2) harvests respectively Vertical lineson bars represent standard error of the means
c c
b b
a
BB
A A
B
Bioc DWB SVB VTB Pro-BX
Leaf
gre
enne
ss (S
PAD
val
ue)
Treatments
00
100
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300
400
500
600
LG1LG2
(a)
a aa a
aC C
A
B
C
Bioc DWB SVB VTB Pro-BXTreatments
00
10
20
30
40
50
60
Ant
hocy
anin
cont
ent (
ACI
)
AC1AC2
(b)
Figure 3 Leaf greenness and anthocyanin content of Swiss chard (Beta vulgaris subsp vulgaris) cv Rhubarb chard as affected by biocharalone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculated biochar (SVB) vermicast tea-inoculated biochar(VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical letters represent mean separation by the least significantdifference (α 005) at the first (1) and the second (2) harvests respectively Vertical lines on bars represent standard error of the means
International Journal of Agronomy 7
surface area and fresh weight at first harvest was Pro-BXgtBiocgtDWB SVBgtVTB (Figures 4(c)ndash4(d)) istrend drastically changed at the second harvest e onlytreatment that increased total leaf area and leaf fresh weightat the second harvest was VTB ie by approximately 102-and 188-fold compared to those at the first harvest On thecontrary total leaf area was significantly (Plt 005) reducedby approximately 042-fold for SVB 074-fold for DWB069-fold for Bioc and 090-fold for Pro-BX (Figure 4(c))while leaf fresh weight was significantly reduced by ap-proximately 033-fold for DWB 028-fold for Bioc and 070-fold for Pro-BX but was not altered by SVB (Figure 4(d)) atthe second harvest as compared to the first harvest A 2-dimensional biplot principal component analysis (PCA) wasused to further explain relationships between the treatmentsand the growth components e PCA biplot explained 92of the variations in the dataset for the plant growth com-ponents as affected by the media treatments Pro-BX BiocDWB SVB and VTB (Figure 5)
ere were distinct differences in the media except thatBioc and DWB were similar and both appeared in the samequadrant on the PCA biplot e plant growth componentsat the first harvest can be found in the first quadrant with thePro-BX treatment is suggested that the PCA plot agreedwith Figures 3 and 4 that the Pro-BX treatment significantlyincreased plant growth components at the first harvest BothSVB and VTB can be found in quadrant 2 of the PCA biplotwith the plant growth components at the second harvestelocation of SVB relative to VTB and the plant growthcomponents suggested that the latter was more effective ininfluencing the plant growth components Neither Bioc norDWB influenced plant growth ese showed that the effectof treatment VTB which was not apparent in the first fourweeks became obvious Additionally VTB recorded thehighest effect on the Swiss chard plant growth componentsat the second harvest us the VTB treatment delayed therelease of nutrients but was made available eventually toincrease the Swiss chard plant growth and yield during theregrowth phase after the first harvest ese findings can beconfirmed by the results of the nutrient release experimentsin Figures 1 and 2 as shown on the PCA biplot
In conclusion the study confirmed that inoculation ofbiochar with vermicast can increase its adsorption capacityfor nutrients which will subsequently be released slowly toplants for root uptake and plant utilization It is evident fromthe present study that the nutrient release rate of inoculatedbiochar is initially slow Vermicast tea-inoculated biocharand solid vermicast-inoculated biochar have similar nutrientrelease patterns and proved to be highly activated Inocu-lated biochar characteristically releases nutrients slowly witha long-lasting impact on growing media environment andultimately plant productivity Comparatively vermicast teawas the most effective in inoculation of the biochar and assuch it was the most efficacious under the conditions of thisstudy Future investigation should consider microbial ac-tivities in these media
e nutrient release plant nutrient uptake and plant growthdata used to support the findings of this study are includedwithin the supplementary information files
Conflicts of Interest
e authors declare that they have no conflicts of interest
Acknowledgments
e authors wish to thank Dr Samuel Asiedu for his as-sistance during the experimentation and Dr NancyMacLean for her guidance on performing the statisticalanalysis However the authors wish to thank Proton PowerInc Tennessee USA for the donation of the biochar
Supplementary Materials
e supplementary files with data showed in S1ndashS11 wereused to report the outcomes of the study e commonacronyms used were as follows Bioc biochar aloneDWB deionized water-inoculated biochar SVB solidvermicast-inoculated biochar VTB vermicast tea-inocu-lated biochar Pro-BXPromix-BX soilless medium aloneS1 the data for the various growing medium salinity contentduring the nutrient release studies S2 the data for thechanges in electric conductivity of the solution when theindividual media were submerged in deionized water S3 thechanges in the acidity level (ie pH) of the solution when the
Figure 5 A two-dimensional principal component analysis biplotshowing relationships among media treatments as active variablesand plant growth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content (AC)plant height (PH) stem diameter (SD) leaf area (LA) and totaledible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc)deionized water-inoculated biochar (DWB) solid vermicast-in-oculated biochar (SVB) vermicast tea-inoculated biochar (VTB)and Promix-BX alone (Pro-BX) at the first (1) and the second (2)harvests respectively
8 International Journal of Agronomy
individual media were submerged in deionized water S4 thetotal dissolved solids in solution when the individual mediawere submerged in deionized water S5 S6 S7 and S8 theconcentrations of calcium potassium nitrate and sodiumions in solution when the individual media were submergedin the deionized water S9 the data for a two-dimensionalprincipal component analysis biplot showing relationshipsamong media treatments as active variables and plantgrowth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content(AC) plant height (PH) stem diameter (SD) leaf area (LA)and total edible leaf fresh weight (LFW) of Swiss chard (Betavulgaris subsp vulgaris) cv Rhubarb chard as affected by thegrowing medium treatments at the first (1) and the second(2) harvests respectively S10 the data for the mineralnutrient composition of the individual growing media be-fore the beginning of the nutrient release studies S11 thedata for plant growth and yield components as affected bythe individual growing medium treatments (SupplementaryMaterials)
References
[1] G Agegnehu A K Srivastava and M I Bird ldquoe role ofbiochar and biochar-compost in improving soil quality andcrop performance a reviewrdquo Applied Soil Ecology vol 119pp 156ndash170 2017
[2] R Xiao M K Awasthi R Li et al ldquoRecent developments inbiochar utilization as an additive in organic solid wastecomposting a reviewrdquo Bioresource Technology vol 246pp 203ndash213 2017
[3] Y Yuan H Chen W Yuan D Williams J T Walker andW Shi ldquoIs biochar-manure co-compost a better solution forsoil health improvement and N2O emissions mitigationrdquo SoilBiology and Biochemistry vol 113 pp 14ndash25 2017
[4] A Grewal L Abbey and L R Gunupuru ldquoProductionprospects and potential application of pyroligneous acid inagriculturerdquo Journal of Analytical and Applied Pyrolysisvol 135 pp 152ndash159 2018
[5] G Agegnehu A M Bass P N Nelson B MuirheadG Wright and M I Bird ldquoBiochar and biochar-compost assoil amendments effects on peanut yield soil properties andgreenhouse gas emissions in tropical North QueenslandAustraliardquo Agriculture Ecosystems amp Environment vol 213pp 72ndash85 2015
[6] N Khan I Clark M A Sanchez-Monedero et al ldquoPhysicaland chemical properties of biochars co-composted withbiowastes and incubated with a chicken litter compostrdquoChemosphere vol 142 pp 14ndash23 2016
[7] F Rees C Germain T Sterckeman and J-L Morel ldquoPlantgrowth and metal uptake by a non-hyperaccumulating species(Lolium perenne) and a Cd-Zn hyperaccumulator (Noccaeacaerulescens) in contaminated soils amended with biocharrdquoPlant and Soil vol 395 no 1-2 pp 57ndash73 2015
[8] J Pietikainen O Kiikkila andH Fritze ldquoCharcoal as a habitatfor microbes and its effect on the microbial community of theunderlying humusrdquo Oikos vol 89 no 2 pp 231ndash242 2000
[9] L Beesley E Moreno-Jimenez and J L Gomez-Eyles ldquoEffectsof biochar and greenwaste compost amendments on mobilitybioavailability and toxicity of inorganic and organic con-taminants in a multi-element polluted soilrdquo EnvironmentalPollution vol 158 no 6 pp 2282ndash2287 2010
[10] N Hagemann K Spokas H-P Schmidt R Kagi M Bohlerand T Bucheli ldquoActivated carbon biochar and charcoallinkages and synergies across pyrogenic carbonrsquos ABCsrdquoWater vol 10 no 2 pp 182ndash201 2018
[11] C Sreenivas S Muralidhar and M S Rao ldquoVermicompost aviable component of IPNSS in nitrogen nutrition of ridgegourdrdquo Annals of Agricultural Research vol 21 no 1pp 108ndash113 2000
[12] AOAC Protein (Crude) in Animal Feed Combustion MethodAOAC Official Method 99003 Official Methods of AnalysisAssociation of Official Analytical Chemists GaithersburgMD USA 17th edition 2003
[13] AOAC Metals and Other Elements in Plants and Pet FoodsInductively Coupled Plasma Spectroscopic Method AOACOfficial Method 96808 Official Methods of Analysis Asso-ciation of Official Analytical Chemists Gaithersburg MDUSA 17th edition 2003
[14] L Abbey S A Rao L N Hodgins and F Briet ldquoDrying andrehydration of vermicasts do not affect nutrient bioavailabilityand seedling growthrdquo American Journal of Plant Nutritionand Fertilization Technology vol 3 no 1 pp 12ndash21 2013
[15] A E Louw-Gaume I M Rao A J Gaume and E FrossardldquoA comparative study on plant growth and root plasticityresponses of two Brachiaria forage grasses grown in nutrientsolution at low and high phosphorus supplyrdquo Plant and Soilvol 328 no 1-2 pp 155ndash164 2010
[16] K Maxwell and G N Johnson ldquoChlorophyll fluorescence-apractical guiderdquo Journal of Experimental Botany vol 51no 345 pp 659ndash668 2000
[17] H Wu C Lai G Zeng et al ldquoe interactions of compostingand biochar and their implications for soil amendment andpollution remediation a reviewrdquo Critical Reviews in Bio-technology vol 37 no 6 pp 754ndash764 2016
[18] T Sizmur T Fresno G Akgul H Frost and E Moreno-Jimenez ldquoBiochar modification to enhance sorption of in-organics from waterrdquo Bioresource Technology vol 246pp 34ndash47 2017
[19] L Martınez-Suller G Provolo D Brennan et al ldquoA note onthe estimation of nutrient value of cattle slurry using easilydetermined physical and chemical parametersrdquo Irish Journalof Agricultural and Food Resarch vol 49 pp 93ndash97 2010
International Journal of Agronomy 9
surrounding growing medium chemistry that it interactswith According to Rees et al [7] the chemical status of soilcan influence the efficacy of biochar
Inoculation of biochar using organic amendment orsynthetic chemical fertilizer triggers its adsorptive surfacewith abundant nutrients in addition to the creation of op-timal microenvironment for microbial growth and increasedwater storage capacity [7ndash10] Ultimately the functionalityof the growing medium is enhanced However the previousstudy showed that by virtue of the high pH biochar canimmobilize major nutrients such as calcium nitrate-nitro-gen and phosphorus [7] is can be a major problem whenusing biochar since these nutrients may become unavailableto plants Also such immobilization activity can influencethe pattern of nutrient release to plants Furthermore theactivities of microbial communities as well as other physicalcharacteristics such as water availability and the structure ofthe growing medium can also influence the release andavailability of nutrients to plants It is therefore hypothesizedthat intentional inoculation of biochar can circumvent thesepotential problems related to nutrient release and plantuptake Materials that can be used to inoculate biocharinclude vermicast thermophilic compost biosolids animalmanure and liquid fertilizer [3] Despite this knowledge thepattern of nutrient release from inoculated biochar usingnatural amendments such as vermicast with respect to timeof application is not well understood is is the main thrustof the current study
Vermicast is rich in microorganisms and plant growth-promoting chemical compounds derived from humic andnonhumic substances which include mineral nutrientsorganic acids nucleic acids macromolecules and antimi-crobial and pesticidal compounds [11] It is therefore ex-pected that the characteristic effect of vermicast-inoculatedbiochar will be significantly higher than if it was not in-oculated as explained by Beesley et al [9] And although thenutrient release rate of the inoculated biochar is expected tobe low it is hypothesized that the synergetic benefits derivedfrom the combination of biochar and vermicast throughinoculation and incubation procedures will be highly effi-cacious e effect of residual nutrients from inoculatedbiochar on plant growth also needs to be investigatederefore the objective of the study was to assess andcompare the nutrient release pattern of solid vermicast-inoculated biochar vermicast tea-inoculated biochar andbiochar alone and their residual effects on plant growth etest plant was Swiss chard (Beta vulgaris subsp vulgaris cvRhubarb chard) which was chosen for its ease of productionduring the cool weather in fall and winter and its ability towithstand sequential harvesting required for the assessmentof plant response to growing medium nutrient residue
2 Materials and Methods
21 Location andMaterials e study was carried out in theCompost and Biostimulant Laboratory and the researchgreenhouse located in the Department of Plant Food andEnvironmental Sciences Dalhousie University Faculty ofAgriculture fromApril to December 2017e biochar from
white pine (Pinus strobus) was produced through pyrolysisat 11000degC and was obtained from Proton Power Inc TNUSA vermicast from red wiggler (Eisenia fetida) was pur-chased from Co-op Country Store Truro NS CanadaPromix-BXtrade (Premier Horticulture Inc QuakertownUSA) a general-purpose peat-based substrate consisted of75ndash85 sphagnum peat moss horticultural-grade perliteand vermiculite chemical fertilizer dolomitic and calciticlimestone a wetting agent and mycorrhizal fungus (Glomusintraradices) was purchased from Halifax Seed Inc HalifaxNS Canada Seeds of Swiss chard (Beta vulgaris subspvulgaris cv Rhubarb chard) was also purchased fromHalifaxSeed Inc
22 Biochar Inoculation and Chemical Analysis e biocharwas inoculated with solid vermicast at 45 moisture con-tent vermicast tea and distilled water alone for 40 days evermicast tea was made by adding a liter of distilled water to100 g of solid vermicast and stirred at 1200 rpm for 24 hrusing DLM1886X1 Isotemp stirring plate (Fisher ScientificInc Markham ON Canada) e biochar was then inoc-ulated with the vermicast tea (VTB) by thoroughly mixing500 g of solid dry biochar and one liter of the vermicast teaprior to incubation e solid vermicast-inoculated biochar(SVB) was made by thoroughly mixing 500 g of the solid drybiochar and 100 g of the solid vermicast prior to incubatione deionized water-inoculated biochar (DWB) was madeby thoroughly mixing 500 g of the dry biochar and one literof deionized water prior to incubation e individualmixtures were then incubated for 40 days in the dark at roomtemperature (ca 21degC) and relative humidity conditionsecontrol treatments were 500 g of the dry biochar alone and500 g of Promix-BX potting mix alone also incubated underthe same room conditions All the treatments were intriplicate Samples (100 g) of each of the growing mediumsubstrates were sent to the Nova Scotia Department ofAgriculture (NSDA) Laboratory Services Truro NS fornutrient analysis Total nitrogen (N) was determined by theAOAC-99003 combustion method [12] using a LECO-SpecAnalyzer (TruSpecreg Micro LECO MI) while calcium (Ca)potassium (K) phosphorus (P) magnesium (Mg) sodium(Na) boron (B) copper (Cu) iron (Fe) manganese (Mn)and zinc (Zn) were determined using the AOAC-96808inductively coupled plasma (ICP) spectrometermethod [13]
23 Nutrient Release and Electrochemical Analysis A nu-trient release study was performed in the laboratory using acylindrical glass jar measuring 35 cm in height and 10 cm forthe inner diameter Each glass jar was filled with one liter ofdeionized water and the dissolved matter and releasednutrients in solution were determined using the methoddescribed by Abbey et al [14] with slight modification Inbrief 20 g of each of the five growing medium treatmentswas placed separately in a HEPA filter grade Rosin Technylon press bag (Rosin Tech Products CA USA) with amesh size of 25 μm and a dimension of 635 cmtimes 1016 cme individual samples were submerged in the deionizedwater in the glass jar 20ml samples of the solution from the
2 International Journal of Agronomy
individual glass jars were collected with replacement every10min for 1 hr every 30min for 2 hr every 1 hr for 5 hrevery 2 hr for 6 hr every 5 hr for 10 hr and every 24 hr for 24days Oakton PC Tester 35 multimeter (Oakton InstrumentsIL USA) was then used to record the pH total dissolvedsolids electric conductivity and salinity of the solutionscollected before pouring them back into the glass jarLAQUA Twin ion meter (HORIBA Minami-ku KyotoJapan) was also used to measure calcium (Ca2+) nitrate(NOminus3) sodium (Na+) and potassium (K+) ion concen-trations of each collected sample per treatment
24 Greenhouse Experiment A pot experiment was per-formed in the departmentrsquos greenhouse at an averagetemperature of 28degC16degC (daynight cycle) and relativehumidity of 76 Supplemental lighting was provided by a600 W HS2000 high-pressure sodium lamps withNAH600579 ballast (PL Light Systems Beamsville ONCanada) at 12 hr light cycle between November and De-cember when days got shorter or on cloudy days Plastic pots(1524 cm diameter) were filled to the same volume of amixture of the individual components as shown in Table 1e variation in weight was due to the differences in bulkdensity (data not presented) e weight of the uninoculateddry biochar prior to inoculation was 200 g Each treatmenthad four potted plants placed in saucers per replication andthey were replicated four times to give a total of 80 ex-perimental units Each pot was planted with one seedling ofSwiss chard and watered with approximately 200ml of tapwater (based on previous work) every two to three daysdepending on the weather conditions By this methodnutrient loss through leachate was avoided
25 Plant GrowthAnalysis Plant height was measured fromthe stem collar to the tip of the longest leaf using a 30 cmruler at first harvest which was four weeks after trans-planting e other growth measurements were stem di-ameter which was measured from the middle portion of thestem using a pair of Mastercraft calipers (Canadian TireToronto ON Canada) total plant fresh weight was recordedprior to total dry weight determination by drying thesamples in an 52100-10 Cole-Parmer mechanical convectionoven dryer (Cole-Parmer Instrumental Company VernonHills Ill USA) at 65degC for 24 hr plant mass density wasdetermined from the dry weights according to the method ofLouw-Gaume et al [15] e number of edible leaves pertreatment was also recorded at first harvest e twoyoungest leaves on each plant were left for the plants toregrow for a second harvest at eight weeks after trans-planting e weights of the harvested leaves were recordedusing an electronic MXX-412 Denver precision balance(Denver Instrument Company CO USA)e total leaf areawas determined using a LI-3100 Leaf Area Meter (Li-CorInc Lincoln NE USA) Measurements of plant height stemdiameter and leaf area were performed again at the secondharvest (ie 8 weeks after transplanting) for comparisonwith those recorded at the first harvest (ie 4 weeks aftertransplanting)
26 Leaf Tissue Pigmentation and Nutrient Analysis Leafgreenness was used to estimate leaf chlorophyll contentusing a 502 SPAD meter (Spectrum Technologies IncAurora Ill USA) Anthocyanin content was estimated usinga portable ACM200+ anthocyanin content meter (Opti-Sciences Inc Hudson NY USA) Chlorophyll fluorescenceindices were used to determine plant stress level usingportable OS30p +Chlorophyll Fluorometer (Opti-SciencesInc Hudson NY USA) e Chlorophyll Fluorometercalculated the maximum quantum yield or efficiency ofphotosystem II as follows
FvFm
Fm minus Fo
Fm1113876 1113877 (1)
where Fo is the minimum fluorescence Fm is the maximumfluorescence and Fv is the variable fluorescence indices [16]
e Swiss chard leaf greenness anthocyanin contentand chlorophyll fluorescence indices were all recorded fromthe 3rd and 4th leaves of each plant per treatment Samples ofplant leaf tissues were also sent to the NSDA LaboratoryServices for nutrient analysis e leaf samples were washedwith distilled water air-dried and then packed in paper bagsbefore sending for nutrients analyses In brief the plant leafsamples were oven-dried at 60degC for 48 hr and ground intopowder Total N Ca K P Mg Na B Cu Fe Mn and Znwere determined using methods described in [12 13]
27 Experimental Design and Statistical Analysis e ex-periment was arranged in a complete randomized designwith four replications for the greenhouse experiment butthree replications for the nutrient release experiment Forthe greenhouse pot experiment each of the five treatmentshad four samples of plants and a total of 16 potted plants pertreatment Data on leaf greenness and anthocyanin contentplant height stem diameter and leaf area were analyzed byone-way analyses of variance (ANOVA) using SAS version94 software (SAS Institute Inc Cary NC USA) Wheneverthe ANOVA indicated a significant difference ie Ple 005Fisherrsquos protected least significant difference (LSD) at α 5was used to separate the means Graphs of pH total dis-solved solids electrical conductivity salinity calcium ni-trate sodium and potassium were plotted for the nutrientrelease experiment using Microsoft Excel A biplot ofprincipal component analysis was performed to determinethe association between the growing media treatments andthe plant growth components of the Swiss chard cv Rhubarbchard using XLSTAT version 191
3 Results and Discussion
Considerable variations were found in the composition ofnutrients in the individual growing medium componentsie the solid vermicast-inoculated biochar (SVB) vermicasttea-inoculated biochar (VTB) deionized water-inoculatedbiochar (DWB) biochar alone (Bioc) and the Promix-BX(Pro-BX) alone (Table 2)e SVB had higher amounts of NP Na B and Zn as compared to all the other biochartreatments except the VTB treatment which had
International Journal of Agronomy 3
comparable amounts of N K Mg and Na However themanufacturerrsquos premixed medium Promix-BX (Pro-BX)with synthetic chemical fertilizer had the highest amounts ofCa Mg and Cu and a similar amount of N as found in theSVB and the VTB e uninoculated biochar (Bioc) that wasused in this study and the DWB had the highest amounts ofMn and Fe respectively but these two treatments containedthe least amounts of all the other remaining nutrients
e richness in nutrients of the two types of vermicast-inoculated biochar (ie SVB andVTB) compared to the Biocand the DWB was expected Cocomposting or combinationof biochar and natural amendments was reported to increasebiochar nutrient adsorption and overall growing mediumfertility status [9 10 17] Typically vermicast is valued for itsrichness and diversity in humic and nonhumic substancesincluding macro- and micronutrients and other plantgrowth factors [11] ese vermicast chemicals can alter theproperties of biochar when combined or cocompostedBased on the reports by Pietikainen et al [8] and Sizmuret al [18] we can fairly suggest that the biochar inoculatedwith the dry solid vermicast (SVB) or the vermicast tea(VTB) became activated with ionized nutrients that en-hanced the functionality of the biochar is assertion willhave to be verified in future studies
e nutrient release experiment showed that initial wateractivity prior to the dissolution of soluble materials such assurface wetting followed by water imbibition by the particlesconstituting the mixed media led to a lag phase within thefirst few hours when they were submerged in the deionizedwater (Figures 1(a)ndash1(d)) Consequently changes in pHtotal dissolved solids (TDS) salinity and electric conduc-tivity (EC) were initially slow before rapidly increasingcontinuously up to the 100th hour (ca 4th day) beforeslowing down to the end of the experiment on the 495th hour(ca day 21) e high positive correlation exiting betweenEC and total nutrient concentration allows for its use toestimate growing medium fertility status [19] Compared toall the other indices the trend for the changes in pH of thesolutions for all the treatments was different (Figure 1(a))
e pH of the solution rapidly declined within the first40min before steeply rising to reach a peak at the 8th hourfollowed by a steep fall at the 24th hour Overall there wereno clear differences in salinity TDS pH and EC of thesolutions for the SVB VTB DWB and the Bioc apart fromthe obvious fluctuations in the line graph for treatmentDWB According to Sizmur et al [18] the manifestation ofchemical sorption is attributed to ion exchange and nu-merous functional groups on the carbonaceous surface ofbiochar As such the fluctuations in the line graphs for theDWB in Figures 1(a)ndash1(d) can be ascribed to low chemical
activity in the deionized water as compared to the vermicast-inoculated biochar treatments e values of all the mea-sured water quality indices for the Pro-BX treatment werefound to be higher than the respective values for SVB VTBDWB and Bioc treatments However the differences beganto show after the 300th hour ese findings demonstratedthe slow release of nutrients from the biochar treatmentscompared to the Pro-BX Particularly the DWB seemed tobe the fastest in releasing its nutrients while the SVB and theBioc seemed to be intermediate It was noticed that therelease of materials into the solution and the pH fortreatment Pro-BX seemed to be generally more stable afterthe 350th hour of sampling compared to the othertreatments
e release of nitrate (NO3minus) into the deionized waterfrom the Pro-BX treatment was the fastest compared to allthe biochar treatments and was followed by a steep declineimmediately after 2 hr of submergence (Figure 2(a)) Afterthe 150th hour the amount of NO3minus released into the so-lution from the Pro-BX did not change However NO3minus
released into solution from the SVB DWB VTB and theBioc showed significant fluctuations throughout the sam-pling period which lasted for 591 hr (ca 246 days) efluctuations can be attributed to microbial and chemicalactivities such as bioconversion of N anion exchange andvolatilization but were not determined in the present studyA lag phase prior to the first 50th hour followed by a rapidincrease in ionic concentrations of K+ Na+ and Ca+2 in thesampled solution (Figures 2(b)ndash2(d)) was also observed econcentrations of K+ and Na+ in the sampled solutions fromall the treatments increased exponentially while that of the
Table 2 Mineral nutrient composition of the growing mediacomponents
Ca2+ seemed to have increased linearly as sampling timeprogressed Amongst the biochar treatments the highest K+
concentration was recorded by the DWB treatment and theleast was recorded by the Bioc treatment while the SVB andthe VTB treatments were in between and not different
Comparatively the release of K+ and Na+ into solutionfrom the Pro-BX was instant and consistently the least justlike the NO3minus is can be attributed to the highly solublenature of K and Na salts However the release of Na+ intosolution was not different amongst the four biochar treat-ments On the contrary the release of Ca2+ into solutionfrom the Pro-BX treatment was the fastest and the highestand was represented by a sigmoidal curve in Figure 2(c) eresult showed that the release of Ca2+ from the Pro-BXsteeply rose after the 100th hour of sampling before levellingoff Overall Ca2+ concentration of all the four biochartreatments fluctuatede release of Ca2+ was highest for theBioc treatment followed by the SVB then the DWB and the
VTB (Figure 2(c)) e fluctuations in the concentrations ofCa2+ released into solution from the biochar treatmentscould be ascribed to ionic exchange activities on the car-bonaceous surface of the biochar erefore the presentresults can be explained by possible modification and ac-tivation of the biochar when it was inoculated with vermicastor deionized water followed by an incubation period asreported by Sizmur et al [18] From Figures 2(a)ndash2(d) itseemed the concentrations of NO3minus K+ Ca2+ and Na+ fromeach of the biochar treatments will continue to rise if thesampling time was extended beyond the 591 hr of the nu-trient release study e variation in the trend of nutrientrelease from the different media treatments is an indicationof possible variations in nutrient availability for plant uptakeand utilization for growth and development
Chlorophyll fluorescence activity was used to assessphotosynthetic activities in Swiss chard cv Rhubarb chardgrown in different treatments It was found that the
Figure 1 Changes in pH total dissolved solids salinity and electric conductivity of solid vermicast-inoculated biochar (solid line greensquare) vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biocharalone (solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard errorbars
International Journal of Agronomy 5
maximum quantum yields also termed as efficiency ofphotosystem II (FvFm) for the Swiss chard plants rangedbetween 076 and 078 and were not significantly (Pgt 005)different between treatments (data not presented) Leafchlorophyll content estimated using the SPAD value of leafgreenness was differentially influenced by the differentmedium treatments Prior to the first harvest ie four weeksafter transplanting the SPAD value was significantly highestin plants grown in the treatment Pro-BX followed bytreatments SVB and VTB and lowest in treatments Bioc andDWB (Figure 3(a))
However there was a remarkable change in the extent towhich the treatments affected the SPAD value of leafgreenness at the second harvest at eight weeks after trans-planting Treatments SVB and VTB equally increased SPADvalue at the second harvest by ca 044-fold compared to thefirst harvest but was remarkably reduced in plants grown inthe Pro-BX by ca 038-fold It was noted that the change washowever moderate in Swiss chard plants grown in the DWBand the Bioc Leaf anthocyanin content was similar for all theplants irrespective of the medium treatment at the firstharvest (Figure 3(b)) At the second harvest only treatmentsVTB and SVB increased leaf anthocyanin contents by ca080- and 095-fold respectively ese findings indicatedthat leaf pigmentation was significantly influenced by VTB
and SVB compared to the other treatments is furtherconfirmed the slow release of nutrients from biochar in-oculated with vermicast
e number of Swiss chard green leaves and plant massdensity which indicate assimilate accumulation were notsignificantly (Pgt 005) different among the treatments andbetween the two harvest times (data not presented) How-ever other plant growth components such as plant heightstem diameter leaf fresh weight and total leaf area wereclearly affected (Figures 4(a)ndash4(d)) ese plant growthcomponents were significantly (Plt 005) increased bytreatment Pro-BX followed by treatments DWB and Biocand the lowest by treatments SVB and VTB at the firstharvest But this growth trend changed at the second harvest
Changes in plant height between the first and the secondharvests were prominent for VTB and SVB It was found thatplant height increased by approximately 203-fold for VTBand by 067-fold for SVB and did not significantly (Pgt 005)change for Bioc or DWB but significantly (Plt 005) reducedby ca 045-fold for Pro-BX Swiss chard plant stem diameterwas increased by approximately 166-fold for VTB and 059-fold for SVB while minor nonsignificant changes wererecorded for Bioc and DWBe Pro-BX on the other handsignificantly (Plt 005) reduced stem diameter by ca 047-fold at the second harvest e trend for both total leaf
Figure 2 Release of potassium sodium nitrate and calcium contents of solid vermicast-inoculated biochar (solid line green square)vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biochar alone(solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard error bars
6 International Journal of Agronomy
b bc bc
aC
C
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
50
100
150
200
250
Plan
t hei
ght (
cm)
PH1PH2
(a)
bcb
c c
a
BCBC
B
A
C
Bioc DWB SVB VTB Pro-BXTreatments
00
20
40
60
80
100
Stem
dia
met
er (m
m)
SD1SD2
(b)
b b bc
a
C CB
A
D
Bioc DWB SVB VTB Pro-BX
Tota
l lea
f fre
sh w
eigh
t (g
plan
t)
Treatments
00
50
100
150
200
250
LFW1LFW2
(c)
bbc
cd
a
BCD
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
150
300
450
600
750
Mea
n le
af ar
ea (c
m2 )
LA1LA2
(d)
Figure 4 Plant height (PH) stem diameter (SD) leaf area (LA) and total edible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculatedbiochar (SVB) vermicast tea-inoculated biochar (VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical lettersrepresent mean separation by the least significant difference (α 005) at the first (1) and the second (2) harvests respectively Vertical lineson bars represent standard error of the means
c c
b b
a
BB
A A
B
Bioc DWB SVB VTB Pro-BX
Leaf
gre
enne
ss (S
PAD
val
ue)
Treatments
00
100
200
300
400
500
600
LG1LG2
(a)
a aa a
aC C
A
B
C
Bioc DWB SVB VTB Pro-BXTreatments
00
10
20
30
40
50
60
Ant
hocy
anin
cont
ent (
ACI
)
AC1AC2
(b)
Figure 3 Leaf greenness and anthocyanin content of Swiss chard (Beta vulgaris subsp vulgaris) cv Rhubarb chard as affected by biocharalone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculated biochar (SVB) vermicast tea-inoculated biochar(VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical letters represent mean separation by the least significantdifference (α 005) at the first (1) and the second (2) harvests respectively Vertical lines on bars represent standard error of the means
International Journal of Agronomy 7
surface area and fresh weight at first harvest was Pro-BXgtBiocgtDWB SVBgtVTB (Figures 4(c)ndash4(d)) istrend drastically changed at the second harvest e onlytreatment that increased total leaf area and leaf fresh weightat the second harvest was VTB ie by approximately 102-and 188-fold compared to those at the first harvest On thecontrary total leaf area was significantly (Plt 005) reducedby approximately 042-fold for SVB 074-fold for DWB069-fold for Bioc and 090-fold for Pro-BX (Figure 4(c))while leaf fresh weight was significantly reduced by ap-proximately 033-fold for DWB 028-fold for Bioc and 070-fold for Pro-BX but was not altered by SVB (Figure 4(d)) atthe second harvest as compared to the first harvest A 2-dimensional biplot principal component analysis (PCA) wasused to further explain relationships between the treatmentsand the growth components e PCA biplot explained 92of the variations in the dataset for the plant growth com-ponents as affected by the media treatments Pro-BX BiocDWB SVB and VTB (Figure 5)
ere were distinct differences in the media except thatBioc and DWB were similar and both appeared in the samequadrant on the PCA biplot e plant growth componentsat the first harvest can be found in the first quadrant with thePro-BX treatment is suggested that the PCA plot agreedwith Figures 3 and 4 that the Pro-BX treatment significantlyincreased plant growth components at the first harvest BothSVB and VTB can be found in quadrant 2 of the PCA biplotwith the plant growth components at the second harvestelocation of SVB relative to VTB and the plant growthcomponents suggested that the latter was more effective ininfluencing the plant growth components Neither Bioc norDWB influenced plant growth ese showed that the effectof treatment VTB which was not apparent in the first fourweeks became obvious Additionally VTB recorded thehighest effect on the Swiss chard plant growth componentsat the second harvest us the VTB treatment delayed therelease of nutrients but was made available eventually toincrease the Swiss chard plant growth and yield during theregrowth phase after the first harvest ese findings can beconfirmed by the results of the nutrient release experimentsin Figures 1 and 2 as shown on the PCA biplot
In conclusion the study confirmed that inoculation ofbiochar with vermicast can increase its adsorption capacityfor nutrients which will subsequently be released slowly toplants for root uptake and plant utilization It is evident fromthe present study that the nutrient release rate of inoculatedbiochar is initially slow Vermicast tea-inoculated biocharand solid vermicast-inoculated biochar have similar nutrientrelease patterns and proved to be highly activated Inocu-lated biochar characteristically releases nutrients slowly witha long-lasting impact on growing media environment andultimately plant productivity Comparatively vermicast teawas the most effective in inoculation of the biochar and assuch it was the most efficacious under the conditions of thisstudy Future investigation should consider microbial ac-tivities in these media
e nutrient release plant nutrient uptake and plant growthdata used to support the findings of this study are includedwithin the supplementary information files
Conflicts of Interest
e authors declare that they have no conflicts of interest
Acknowledgments
e authors wish to thank Dr Samuel Asiedu for his as-sistance during the experimentation and Dr NancyMacLean for her guidance on performing the statisticalanalysis However the authors wish to thank Proton PowerInc Tennessee USA for the donation of the biochar
Supplementary Materials
e supplementary files with data showed in S1ndashS11 wereused to report the outcomes of the study e commonacronyms used were as follows Bioc biochar aloneDWB deionized water-inoculated biochar SVB solidvermicast-inoculated biochar VTB vermicast tea-inocu-lated biochar Pro-BXPromix-BX soilless medium aloneS1 the data for the various growing medium salinity contentduring the nutrient release studies S2 the data for thechanges in electric conductivity of the solution when theindividual media were submerged in deionized water S3 thechanges in the acidity level (ie pH) of the solution when the
Figure 5 A two-dimensional principal component analysis biplotshowing relationships among media treatments as active variablesand plant growth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content (AC)plant height (PH) stem diameter (SD) leaf area (LA) and totaledible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc)deionized water-inoculated biochar (DWB) solid vermicast-in-oculated biochar (SVB) vermicast tea-inoculated biochar (VTB)and Promix-BX alone (Pro-BX) at the first (1) and the second (2)harvests respectively
8 International Journal of Agronomy
individual media were submerged in deionized water S4 thetotal dissolved solids in solution when the individual mediawere submerged in deionized water S5 S6 S7 and S8 theconcentrations of calcium potassium nitrate and sodiumions in solution when the individual media were submergedin the deionized water S9 the data for a two-dimensionalprincipal component analysis biplot showing relationshipsamong media treatments as active variables and plantgrowth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content(AC) plant height (PH) stem diameter (SD) leaf area (LA)and total edible leaf fresh weight (LFW) of Swiss chard (Betavulgaris subsp vulgaris) cv Rhubarb chard as affected by thegrowing medium treatments at the first (1) and the second(2) harvests respectively S10 the data for the mineralnutrient composition of the individual growing media be-fore the beginning of the nutrient release studies S11 thedata for plant growth and yield components as affected bythe individual growing medium treatments (SupplementaryMaterials)
References
[1] G Agegnehu A K Srivastava and M I Bird ldquoe role ofbiochar and biochar-compost in improving soil quality andcrop performance a reviewrdquo Applied Soil Ecology vol 119pp 156ndash170 2017
[2] R Xiao M K Awasthi R Li et al ldquoRecent developments inbiochar utilization as an additive in organic solid wastecomposting a reviewrdquo Bioresource Technology vol 246pp 203ndash213 2017
[3] Y Yuan H Chen W Yuan D Williams J T Walker andW Shi ldquoIs biochar-manure co-compost a better solution forsoil health improvement and N2O emissions mitigationrdquo SoilBiology and Biochemistry vol 113 pp 14ndash25 2017
[4] A Grewal L Abbey and L R Gunupuru ldquoProductionprospects and potential application of pyroligneous acid inagriculturerdquo Journal of Analytical and Applied Pyrolysisvol 135 pp 152ndash159 2018
[5] G Agegnehu A M Bass P N Nelson B MuirheadG Wright and M I Bird ldquoBiochar and biochar-compost assoil amendments effects on peanut yield soil properties andgreenhouse gas emissions in tropical North QueenslandAustraliardquo Agriculture Ecosystems amp Environment vol 213pp 72ndash85 2015
[6] N Khan I Clark M A Sanchez-Monedero et al ldquoPhysicaland chemical properties of biochars co-composted withbiowastes and incubated with a chicken litter compostrdquoChemosphere vol 142 pp 14ndash23 2016
[7] F Rees C Germain T Sterckeman and J-L Morel ldquoPlantgrowth and metal uptake by a non-hyperaccumulating species(Lolium perenne) and a Cd-Zn hyperaccumulator (Noccaeacaerulescens) in contaminated soils amended with biocharrdquoPlant and Soil vol 395 no 1-2 pp 57ndash73 2015
[8] J Pietikainen O Kiikkila andH Fritze ldquoCharcoal as a habitatfor microbes and its effect on the microbial community of theunderlying humusrdquo Oikos vol 89 no 2 pp 231ndash242 2000
[9] L Beesley E Moreno-Jimenez and J L Gomez-Eyles ldquoEffectsof biochar and greenwaste compost amendments on mobilitybioavailability and toxicity of inorganic and organic con-taminants in a multi-element polluted soilrdquo EnvironmentalPollution vol 158 no 6 pp 2282ndash2287 2010
[10] N Hagemann K Spokas H-P Schmidt R Kagi M Bohlerand T Bucheli ldquoActivated carbon biochar and charcoallinkages and synergies across pyrogenic carbonrsquos ABCsrdquoWater vol 10 no 2 pp 182ndash201 2018
[11] C Sreenivas S Muralidhar and M S Rao ldquoVermicompost aviable component of IPNSS in nitrogen nutrition of ridgegourdrdquo Annals of Agricultural Research vol 21 no 1pp 108ndash113 2000
[12] AOAC Protein (Crude) in Animal Feed Combustion MethodAOAC Official Method 99003 Official Methods of AnalysisAssociation of Official Analytical Chemists GaithersburgMD USA 17th edition 2003
[13] AOAC Metals and Other Elements in Plants and Pet FoodsInductively Coupled Plasma Spectroscopic Method AOACOfficial Method 96808 Official Methods of Analysis Asso-ciation of Official Analytical Chemists Gaithersburg MDUSA 17th edition 2003
[14] L Abbey S A Rao L N Hodgins and F Briet ldquoDrying andrehydration of vermicasts do not affect nutrient bioavailabilityand seedling growthrdquo American Journal of Plant Nutritionand Fertilization Technology vol 3 no 1 pp 12ndash21 2013
[15] A E Louw-Gaume I M Rao A J Gaume and E FrossardldquoA comparative study on plant growth and root plasticityresponses of two Brachiaria forage grasses grown in nutrientsolution at low and high phosphorus supplyrdquo Plant and Soilvol 328 no 1-2 pp 155ndash164 2010
[16] K Maxwell and G N Johnson ldquoChlorophyll fluorescence-apractical guiderdquo Journal of Experimental Botany vol 51no 345 pp 659ndash668 2000
[17] H Wu C Lai G Zeng et al ldquoe interactions of compostingand biochar and their implications for soil amendment andpollution remediation a reviewrdquo Critical Reviews in Bio-technology vol 37 no 6 pp 754ndash764 2016
[18] T Sizmur T Fresno G Akgul H Frost and E Moreno-Jimenez ldquoBiochar modification to enhance sorption of in-organics from waterrdquo Bioresource Technology vol 246pp 34ndash47 2017
[19] L Martınez-Suller G Provolo D Brennan et al ldquoA note onthe estimation of nutrient value of cattle slurry using easilydetermined physical and chemical parametersrdquo Irish Journalof Agricultural and Food Resarch vol 49 pp 93ndash97 2010
International Journal of Agronomy 9
individual glass jars were collected with replacement every10min for 1 hr every 30min for 2 hr every 1 hr for 5 hrevery 2 hr for 6 hr every 5 hr for 10 hr and every 24 hr for 24days Oakton PC Tester 35 multimeter (Oakton InstrumentsIL USA) was then used to record the pH total dissolvedsolids electric conductivity and salinity of the solutionscollected before pouring them back into the glass jarLAQUA Twin ion meter (HORIBA Minami-ku KyotoJapan) was also used to measure calcium (Ca2+) nitrate(NOminus3) sodium (Na+) and potassium (K+) ion concen-trations of each collected sample per treatment
24 Greenhouse Experiment A pot experiment was per-formed in the departmentrsquos greenhouse at an averagetemperature of 28degC16degC (daynight cycle) and relativehumidity of 76 Supplemental lighting was provided by a600 W HS2000 high-pressure sodium lamps withNAH600579 ballast (PL Light Systems Beamsville ONCanada) at 12 hr light cycle between November and De-cember when days got shorter or on cloudy days Plastic pots(1524 cm diameter) were filled to the same volume of amixture of the individual components as shown in Table 1e variation in weight was due to the differences in bulkdensity (data not presented) e weight of the uninoculateddry biochar prior to inoculation was 200 g Each treatmenthad four potted plants placed in saucers per replication andthey were replicated four times to give a total of 80 ex-perimental units Each pot was planted with one seedling ofSwiss chard and watered with approximately 200ml of tapwater (based on previous work) every two to three daysdepending on the weather conditions By this methodnutrient loss through leachate was avoided
25 Plant GrowthAnalysis Plant height was measured fromthe stem collar to the tip of the longest leaf using a 30 cmruler at first harvest which was four weeks after trans-planting e other growth measurements were stem di-ameter which was measured from the middle portion of thestem using a pair of Mastercraft calipers (Canadian TireToronto ON Canada) total plant fresh weight was recordedprior to total dry weight determination by drying thesamples in an 52100-10 Cole-Parmer mechanical convectionoven dryer (Cole-Parmer Instrumental Company VernonHills Ill USA) at 65degC for 24 hr plant mass density wasdetermined from the dry weights according to the method ofLouw-Gaume et al [15] e number of edible leaves pertreatment was also recorded at first harvest e twoyoungest leaves on each plant were left for the plants toregrow for a second harvest at eight weeks after trans-planting e weights of the harvested leaves were recordedusing an electronic MXX-412 Denver precision balance(Denver Instrument Company CO USA)e total leaf areawas determined using a LI-3100 Leaf Area Meter (Li-CorInc Lincoln NE USA) Measurements of plant height stemdiameter and leaf area were performed again at the secondharvest (ie 8 weeks after transplanting) for comparisonwith those recorded at the first harvest (ie 4 weeks aftertransplanting)
26 Leaf Tissue Pigmentation and Nutrient Analysis Leafgreenness was used to estimate leaf chlorophyll contentusing a 502 SPAD meter (Spectrum Technologies IncAurora Ill USA) Anthocyanin content was estimated usinga portable ACM200+ anthocyanin content meter (Opti-Sciences Inc Hudson NY USA) Chlorophyll fluorescenceindices were used to determine plant stress level usingportable OS30p +Chlorophyll Fluorometer (Opti-SciencesInc Hudson NY USA) e Chlorophyll Fluorometercalculated the maximum quantum yield or efficiency ofphotosystem II as follows
FvFm
Fm minus Fo
Fm1113876 1113877 (1)
where Fo is the minimum fluorescence Fm is the maximumfluorescence and Fv is the variable fluorescence indices [16]
e Swiss chard leaf greenness anthocyanin contentand chlorophyll fluorescence indices were all recorded fromthe 3rd and 4th leaves of each plant per treatment Samples ofplant leaf tissues were also sent to the NSDA LaboratoryServices for nutrient analysis e leaf samples were washedwith distilled water air-dried and then packed in paper bagsbefore sending for nutrients analyses In brief the plant leafsamples were oven-dried at 60degC for 48 hr and ground intopowder Total N Ca K P Mg Na B Cu Fe Mn and Znwere determined using methods described in [12 13]
27 Experimental Design and Statistical Analysis e ex-periment was arranged in a complete randomized designwith four replications for the greenhouse experiment butthree replications for the nutrient release experiment Forthe greenhouse pot experiment each of the five treatmentshad four samples of plants and a total of 16 potted plants pertreatment Data on leaf greenness and anthocyanin contentplant height stem diameter and leaf area were analyzed byone-way analyses of variance (ANOVA) using SAS version94 software (SAS Institute Inc Cary NC USA) Wheneverthe ANOVA indicated a significant difference ie Ple 005Fisherrsquos protected least significant difference (LSD) at α 5was used to separate the means Graphs of pH total dis-solved solids electrical conductivity salinity calcium ni-trate sodium and potassium were plotted for the nutrientrelease experiment using Microsoft Excel A biplot ofprincipal component analysis was performed to determinethe association between the growing media treatments andthe plant growth components of the Swiss chard cv Rhubarbchard using XLSTAT version 191
3 Results and Discussion
Considerable variations were found in the composition ofnutrients in the individual growing medium componentsie the solid vermicast-inoculated biochar (SVB) vermicasttea-inoculated biochar (VTB) deionized water-inoculatedbiochar (DWB) biochar alone (Bioc) and the Promix-BX(Pro-BX) alone (Table 2)e SVB had higher amounts of NP Na B and Zn as compared to all the other biochartreatments except the VTB treatment which had
International Journal of Agronomy 3
comparable amounts of N K Mg and Na However themanufacturerrsquos premixed medium Promix-BX (Pro-BX)with synthetic chemical fertilizer had the highest amounts ofCa Mg and Cu and a similar amount of N as found in theSVB and the VTB e uninoculated biochar (Bioc) that wasused in this study and the DWB had the highest amounts ofMn and Fe respectively but these two treatments containedthe least amounts of all the other remaining nutrients
e richness in nutrients of the two types of vermicast-inoculated biochar (ie SVB andVTB) compared to the Biocand the DWB was expected Cocomposting or combinationof biochar and natural amendments was reported to increasebiochar nutrient adsorption and overall growing mediumfertility status [9 10 17] Typically vermicast is valued for itsrichness and diversity in humic and nonhumic substancesincluding macro- and micronutrients and other plantgrowth factors [11] ese vermicast chemicals can alter theproperties of biochar when combined or cocompostedBased on the reports by Pietikainen et al [8] and Sizmuret al [18] we can fairly suggest that the biochar inoculatedwith the dry solid vermicast (SVB) or the vermicast tea(VTB) became activated with ionized nutrients that en-hanced the functionality of the biochar is assertion willhave to be verified in future studies
e nutrient release experiment showed that initial wateractivity prior to the dissolution of soluble materials such assurface wetting followed by water imbibition by the particlesconstituting the mixed media led to a lag phase within thefirst few hours when they were submerged in the deionizedwater (Figures 1(a)ndash1(d)) Consequently changes in pHtotal dissolved solids (TDS) salinity and electric conduc-tivity (EC) were initially slow before rapidly increasingcontinuously up to the 100th hour (ca 4th day) beforeslowing down to the end of the experiment on the 495th hour(ca day 21) e high positive correlation exiting betweenEC and total nutrient concentration allows for its use toestimate growing medium fertility status [19] Compared toall the other indices the trend for the changes in pH of thesolutions for all the treatments was different (Figure 1(a))
e pH of the solution rapidly declined within the first40min before steeply rising to reach a peak at the 8th hourfollowed by a steep fall at the 24th hour Overall there wereno clear differences in salinity TDS pH and EC of thesolutions for the SVB VTB DWB and the Bioc apart fromthe obvious fluctuations in the line graph for treatmentDWB According to Sizmur et al [18] the manifestation ofchemical sorption is attributed to ion exchange and nu-merous functional groups on the carbonaceous surface ofbiochar As such the fluctuations in the line graphs for theDWB in Figures 1(a)ndash1(d) can be ascribed to low chemical
activity in the deionized water as compared to the vermicast-inoculated biochar treatments e values of all the mea-sured water quality indices for the Pro-BX treatment werefound to be higher than the respective values for SVB VTBDWB and Bioc treatments However the differences beganto show after the 300th hour ese findings demonstratedthe slow release of nutrients from the biochar treatmentscompared to the Pro-BX Particularly the DWB seemed tobe the fastest in releasing its nutrients while the SVB and theBioc seemed to be intermediate It was noticed that therelease of materials into the solution and the pH fortreatment Pro-BX seemed to be generally more stable afterthe 350th hour of sampling compared to the othertreatments
e release of nitrate (NO3minus) into the deionized waterfrom the Pro-BX treatment was the fastest compared to allthe biochar treatments and was followed by a steep declineimmediately after 2 hr of submergence (Figure 2(a)) Afterthe 150th hour the amount of NO3minus released into the so-lution from the Pro-BX did not change However NO3minus
released into solution from the SVB DWB VTB and theBioc showed significant fluctuations throughout the sam-pling period which lasted for 591 hr (ca 246 days) efluctuations can be attributed to microbial and chemicalactivities such as bioconversion of N anion exchange andvolatilization but were not determined in the present studyA lag phase prior to the first 50th hour followed by a rapidincrease in ionic concentrations of K+ Na+ and Ca+2 in thesampled solution (Figures 2(b)ndash2(d)) was also observed econcentrations of K+ and Na+ in the sampled solutions fromall the treatments increased exponentially while that of the
Table 2 Mineral nutrient composition of the growing mediacomponents
Ca2+ seemed to have increased linearly as sampling timeprogressed Amongst the biochar treatments the highest K+
concentration was recorded by the DWB treatment and theleast was recorded by the Bioc treatment while the SVB andthe VTB treatments were in between and not different
Comparatively the release of K+ and Na+ into solutionfrom the Pro-BX was instant and consistently the least justlike the NO3minus is can be attributed to the highly solublenature of K and Na salts However the release of Na+ intosolution was not different amongst the four biochar treat-ments On the contrary the release of Ca2+ into solutionfrom the Pro-BX treatment was the fastest and the highestand was represented by a sigmoidal curve in Figure 2(c) eresult showed that the release of Ca2+ from the Pro-BXsteeply rose after the 100th hour of sampling before levellingoff Overall Ca2+ concentration of all the four biochartreatments fluctuatede release of Ca2+ was highest for theBioc treatment followed by the SVB then the DWB and the
VTB (Figure 2(c)) e fluctuations in the concentrations ofCa2+ released into solution from the biochar treatmentscould be ascribed to ionic exchange activities on the car-bonaceous surface of the biochar erefore the presentresults can be explained by possible modification and ac-tivation of the biochar when it was inoculated with vermicastor deionized water followed by an incubation period asreported by Sizmur et al [18] From Figures 2(a)ndash2(d) itseemed the concentrations of NO3minus K+ Ca2+ and Na+ fromeach of the biochar treatments will continue to rise if thesampling time was extended beyond the 591 hr of the nu-trient release study e variation in the trend of nutrientrelease from the different media treatments is an indicationof possible variations in nutrient availability for plant uptakeand utilization for growth and development
Chlorophyll fluorescence activity was used to assessphotosynthetic activities in Swiss chard cv Rhubarb chardgrown in different treatments It was found that the
Figure 1 Changes in pH total dissolved solids salinity and electric conductivity of solid vermicast-inoculated biochar (solid line greensquare) vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biocharalone (solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard errorbars
International Journal of Agronomy 5
maximum quantum yields also termed as efficiency ofphotosystem II (FvFm) for the Swiss chard plants rangedbetween 076 and 078 and were not significantly (Pgt 005)different between treatments (data not presented) Leafchlorophyll content estimated using the SPAD value of leafgreenness was differentially influenced by the differentmedium treatments Prior to the first harvest ie four weeksafter transplanting the SPAD value was significantly highestin plants grown in the treatment Pro-BX followed bytreatments SVB and VTB and lowest in treatments Bioc andDWB (Figure 3(a))
However there was a remarkable change in the extent towhich the treatments affected the SPAD value of leafgreenness at the second harvest at eight weeks after trans-planting Treatments SVB and VTB equally increased SPADvalue at the second harvest by ca 044-fold compared to thefirst harvest but was remarkably reduced in plants grown inthe Pro-BX by ca 038-fold It was noted that the change washowever moderate in Swiss chard plants grown in the DWBand the Bioc Leaf anthocyanin content was similar for all theplants irrespective of the medium treatment at the firstharvest (Figure 3(b)) At the second harvest only treatmentsVTB and SVB increased leaf anthocyanin contents by ca080- and 095-fold respectively ese findings indicatedthat leaf pigmentation was significantly influenced by VTB
and SVB compared to the other treatments is furtherconfirmed the slow release of nutrients from biochar in-oculated with vermicast
e number of Swiss chard green leaves and plant massdensity which indicate assimilate accumulation were notsignificantly (Pgt 005) different among the treatments andbetween the two harvest times (data not presented) How-ever other plant growth components such as plant heightstem diameter leaf fresh weight and total leaf area wereclearly affected (Figures 4(a)ndash4(d)) ese plant growthcomponents were significantly (Plt 005) increased bytreatment Pro-BX followed by treatments DWB and Biocand the lowest by treatments SVB and VTB at the firstharvest But this growth trend changed at the second harvest
Changes in plant height between the first and the secondharvests were prominent for VTB and SVB It was found thatplant height increased by approximately 203-fold for VTBand by 067-fold for SVB and did not significantly (Pgt 005)change for Bioc or DWB but significantly (Plt 005) reducedby ca 045-fold for Pro-BX Swiss chard plant stem diameterwas increased by approximately 166-fold for VTB and 059-fold for SVB while minor nonsignificant changes wererecorded for Bioc and DWBe Pro-BX on the other handsignificantly (Plt 005) reduced stem diameter by ca 047-fold at the second harvest e trend for both total leaf
Figure 2 Release of potassium sodium nitrate and calcium contents of solid vermicast-inoculated biochar (solid line green square)vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biochar alone(solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard error bars
6 International Journal of Agronomy
b bc bc
aC
C
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
50
100
150
200
250
Plan
t hei
ght (
cm)
PH1PH2
(a)
bcb
c c
a
BCBC
B
A
C
Bioc DWB SVB VTB Pro-BXTreatments
00
20
40
60
80
100
Stem
dia
met
er (m
m)
SD1SD2
(b)
b b bc
a
C CB
A
D
Bioc DWB SVB VTB Pro-BX
Tota
l lea
f fre
sh w
eigh
t (g
plan
t)
Treatments
00
50
100
150
200
250
LFW1LFW2
(c)
bbc
cd
a
BCD
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
150
300
450
600
750
Mea
n le
af ar
ea (c
m2 )
LA1LA2
(d)
Figure 4 Plant height (PH) stem diameter (SD) leaf area (LA) and total edible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculatedbiochar (SVB) vermicast tea-inoculated biochar (VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical lettersrepresent mean separation by the least significant difference (α 005) at the first (1) and the second (2) harvests respectively Vertical lineson bars represent standard error of the means
c c
b b
a
BB
A A
B
Bioc DWB SVB VTB Pro-BX
Leaf
gre
enne
ss (S
PAD
val
ue)
Treatments
00
100
200
300
400
500
600
LG1LG2
(a)
a aa a
aC C
A
B
C
Bioc DWB SVB VTB Pro-BXTreatments
00
10
20
30
40
50
60
Ant
hocy
anin
cont
ent (
ACI
)
AC1AC2
(b)
Figure 3 Leaf greenness and anthocyanin content of Swiss chard (Beta vulgaris subsp vulgaris) cv Rhubarb chard as affected by biocharalone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculated biochar (SVB) vermicast tea-inoculated biochar(VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical letters represent mean separation by the least significantdifference (α 005) at the first (1) and the second (2) harvests respectively Vertical lines on bars represent standard error of the means
International Journal of Agronomy 7
surface area and fresh weight at first harvest was Pro-BXgtBiocgtDWB SVBgtVTB (Figures 4(c)ndash4(d)) istrend drastically changed at the second harvest e onlytreatment that increased total leaf area and leaf fresh weightat the second harvest was VTB ie by approximately 102-and 188-fold compared to those at the first harvest On thecontrary total leaf area was significantly (Plt 005) reducedby approximately 042-fold for SVB 074-fold for DWB069-fold for Bioc and 090-fold for Pro-BX (Figure 4(c))while leaf fresh weight was significantly reduced by ap-proximately 033-fold for DWB 028-fold for Bioc and 070-fold for Pro-BX but was not altered by SVB (Figure 4(d)) atthe second harvest as compared to the first harvest A 2-dimensional biplot principal component analysis (PCA) wasused to further explain relationships between the treatmentsand the growth components e PCA biplot explained 92of the variations in the dataset for the plant growth com-ponents as affected by the media treatments Pro-BX BiocDWB SVB and VTB (Figure 5)
ere were distinct differences in the media except thatBioc and DWB were similar and both appeared in the samequadrant on the PCA biplot e plant growth componentsat the first harvest can be found in the first quadrant with thePro-BX treatment is suggested that the PCA plot agreedwith Figures 3 and 4 that the Pro-BX treatment significantlyincreased plant growth components at the first harvest BothSVB and VTB can be found in quadrant 2 of the PCA biplotwith the plant growth components at the second harvestelocation of SVB relative to VTB and the plant growthcomponents suggested that the latter was more effective ininfluencing the plant growth components Neither Bioc norDWB influenced plant growth ese showed that the effectof treatment VTB which was not apparent in the first fourweeks became obvious Additionally VTB recorded thehighest effect on the Swiss chard plant growth componentsat the second harvest us the VTB treatment delayed therelease of nutrients but was made available eventually toincrease the Swiss chard plant growth and yield during theregrowth phase after the first harvest ese findings can beconfirmed by the results of the nutrient release experimentsin Figures 1 and 2 as shown on the PCA biplot
In conclusion the study confirmed that inoculation ofbiochar with vermicast can increase its adsorption capacityfor nutrients which will subsequently be released slowly toplants for root uptake and plant utilization It is evident fromthe present study that the nutrient release rate of inoculatedbiochar is initially slow Vermicast tea-inoculated biocharand solid vermicast-inoculated biochar have similar nutrientrelease patterns and proved to be highly activated Inocu-lated biochar characteristically releases nutrients slowly witha long-lasting impact on growing media environment andultimately plant productivity Comparatively vermicast teawas the most effective in inoculation of the biochar and assuch it was the most efficacious under the conditions of thisstudy Future investigation should consider microbial ac-tivities in these media
e nutrient release plant nutrient uptake and plant growthdata used to support the findings of this study are includedwithin the supplementary information files
Conflicts of Interest
e authors declare that they have no conflicts of interest
Acknowledgments
e authors wish to thank Dr Samuel Asiedu for his as-sistance during the experimentation and Dr NancyMacLean for her guidance on performing the statisticalanalysis However the authors wish to thank Proton PowerInc Tennessee USA for the donation of the biochar
Supplementary Materials
e supplementary files with data showed in S1ndashS11 wereused to report the outcomes of the study e commonacronyms used were as follows Bioc biochar aloneDWB deionized water-inoculated biochar SVB solidvermicast-inoculated biochar VTB vermicast tea-inocu-lated biochar Pro-BXPromix-BX soilless medium aloneS1 the data for the various growing medium salinity contentduring the nutrient release studies S2 the data for thechanges in electric conductivity of the solution when theindividual media were submerged in deionized water S3 thechanges in the acidity level (ie pH) of the solution when the
Figure 5 A two-dimensional principal component analysis biplotshowing relationships among media treatments as active variablesand plant growth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content (AC)plant height (PH) stem diameter (SD) leaf area (LA) and totaledible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc)deionized water-inoculated biochar (DWB) solid vermicast-in-oculated biochar (SVB) vermicast tea-inoculated biochar (VTB)and Promix-BX alone (Pro-BX) at the first (1) and the second (2)harvests respectively
8 International Journal of Agronomy
individual media were submerged in deionized water S4 thetotal dissolved solids in solution when the individual mediawere submerged in deionized water S5 S6 S7 and S8 theconcentrations of calcium potassium nitrate and sodiumions in solution when the individual media were submergedin the deionized water S9 the data for a two-dimensionalprincipal component analysis biplot showing relationshipsamong media treatments as active variables and plantgrowth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content(AC) plant height (PH) stem diameter (SD) leaf area (LA)and total edible leaf fresh weight (LFW) of Swiss chard (Betavulgaris subsp vulgaris) cv Rhubarb chard as affected by thegrowing medium treatments at the first (1) and the second(2) harvests respectively S10 the data for the mineralnutrient composition of the individual growing media be-fore the beginning of the nutrient release studies S11 thedata for plant growth and yield components as affected bythe individual growing medium treatments (SupplementaryMaterials)
References
[1] G Agegnehu A K Srivastava and M I Bird ldquoe role ofbiochar and biochar-compost in improving soil quality andcrop performance a reviewrdquo Applied Soil Ecology vol 119pp 156ndash170 2017
[2] R Xiao M K Awasthi R Li et al ldquoRecent developments inbiochar utilization as an additive in organic solid wastecomposting a reviewrdquo Bioresource Technology vol 246pp 203ndash213 2017
[3] Y Yuan H Chen W Yuan D Williams J T Walker andW Shi ldquoIs biochar-manure co-compost a better solution forsoil health improvement and N2O emissions mitigationrdquo SoilBiology and Biochemistry vol 113 pp 14ndash25 2017
[4] A Grewal L Abbey and L R Gunupuru ldquoProductionprospects and potential application of pyroligneous acid inagriculturerdquo Journal of Analytical and Applied Pyrolysisvol 135 pp 152ndash159 2018
[5] G Agegnehu A M Bass P N Nelson B MuirheadG Wright and M I Bird ldquoBiochar and biochar-compost assoil amendments effects on peanut yield soil properties andgreenhouse gas emissions in tropical North QueenslandAustraliardquo Agriculture Ecosystems amp Environment vol 213pp 72ndash85 2015
[6] N Khan I Clark M A Sanchez-Monedero et al ldquoPhysicaland chemical properties of biochars co-composted withbiowastes and incubated with a chicken litter compostrdquoChemosphere vol 142 pp 14ndash23 2016
[7] F Rees C Germain T Sterckeman and J-L Morel ldquoPlantgrowth and metal uptake by a non-hyperaccumulating species(Lolium perenne) and a Cd-Zn hyperaccumulator (Noccaeacaerulescens) in contaminated soils amended with biocharrdquoPlant and Soil vol 395 no 1-2 pp 57ndash73 2015
[8] J Pietikainen O Kiikkila andH Fritze ldquoCharcoal as a habitatfor microbes and its effect on the microbial community of theunderlying humusrdquo Oikos vol 89 no 2 pp 231ndash242 2000
[9] L Beesley E Moreno-Jimenez and J L Gomez-Eyles ldquoEffectsof biochar and greenwaste compost amendments on mobilitybioavailability and toxicity of inorganic and organic con-taminants in a multi-element polluted soilrdquo EnvironmentalPollution vol 158 no 6 pp 2282ndash2287 2010
[10] N Hagemann K Spokas H-P Schmidt R Kagi M Bohlerand T Bucheli ldquoActivated carbon biochar and charcoallinkages and synergies across pyrogenic carbonrsquos ABCsrdquoWater vol 10 no 2 pp 182ndash201 2018
[11] C Sreenivas S Muralidhar and M S Rao ldquoVermicompost aviable component of IPNSS in nitrogen nutrition of ridgegourdrdquo Annals of Agricultural Research vol 21 no 1pp 108ndash113 2000
[12] AOAC Protein (Crude) in Animal Feed Combustion MethodAOAC Official Method 99003 Official Methods of AnalysisAssociation of Official Analytical Chemists GaithersburgMD USA 17th edition 2003
[13] AOAC Metals and Other Elements in Plants and Pet FoodsInductively Coupled Plasma Spectroscopic Method AOACOfficial Method 96808 Official Methods of Analysis Asso-ciation of Official Analytical Chemists Gaithersburg MDUSA 17th edition 2003
[14] L Abbey S A Rao L N Hodgins and F Briet ldquoDrying andrehydration of vermicasts do not affect nutrient bioavailabilityand seedling growthrdquo American Journal of Plant Nutritionand Fertilization Technology vol 3 no 1 pp 12ndash21 2013
[15] A E Louw-Gaume I M Rao A J Gaume and E FrossardldquoA comparative study on plant growth and root plasticityresponses of two Brachiaria forage grasses grown in nutrientsolution at low and high phosphorus supplyrdquo Plant and Soilvol 328 no 1-2 pp 155ndash164 2010
[16] K Maxwell and G N Johnson ldquoChlorophyll fluorescence-apractical guiderdquo Journal of Experimental Botany vol 51no 345 pp 659ndash668 2000
[17] H Wu C Lai G Zeng et al ldquoe interactions of compostingand biochar and their implications for soil amendment andpollution remediation a reviewrdquo Critical Reviews in Bio-technology vol 37 no 6 pp 754ndash764 2016
[18] T Sizmur T Fresno G Akgul H Frost and E Moreno-Jimenez ldquoBiochar modification to enhance sorption of in-organics from waterrdquo Bioresource Technology vol 246pp 34ndash47 2017
[19] L Martınez-Suller G Provolo D Brennan et al ldquoA note onthe estimation of nutrient value of cattle slurry using easilydetermined physical and chemical parametersrdquo Irish Journalof Agricultural and Food Resarch vol 49 pp 93ndash97 2010
International Journal of Agronomy 9
comparable amounts of N K Mg and Na However themanufacturerrsquos premixed medium Promix-BX (Pro-BX)with synthetic chemical fertilizer had the highest amounts ofCa Mg and Cu and a similar amount of N as found in theSVB and the VTB e uninoculated biochar (Bioc) that wasused in this study and the DWB had the highest amounts ofMn and Fe respectively but these two treatments containedthe least amounts of all the other remaining nutrients
e richness in nutrients of the two types of vermicast-inoculated biochar (ie SVB andVTB) compared to the Biocand the DWB was expected Cocomposting or combinationof biochar and natural amendments was reported to increasebiochar nutrient adsorption and overall growing mediumfertility status [9 10 17] Typically vermicast is valued for itsrichness and diversity in humic and nonhumic substancesincluding macro- and micronutrients and other plantgrowth factors [11] ese vermicast chemicals can alter theproperties of biochar when combined or cocompostedBased on the reports by Pietikainen et al [8] and Sizmuret al [18] we can fairly suggest that the biochar inoculatedwith the dry solid vermicast (SVB) or the vermicast tea(VTB) became activated with ionized nutrients that en-hanced the functionality of the biochar is assertion willhave to be verified in future studies
e nutrient release experiment showed that initial wateractivity prior to the dissolution of soluble materials such assurface wetting followed by water imbibition by the particlesconstituting the mixed media led to a lag phase within thefirst few hours when they were submerged in the deionizedwater (Figures 1(a)ndash1(d)) Consequently changes in pHtotal dissolved solids (TDS) salinity and electric conduc-tivity (EC) were initially slow before rapidly increasingcontinuously up to the 100th hour (ca 4th day) beforeslowing down to the end of the experiment on the 495th hour(ca day 21) e high positive correlation exiting betweenEC and total nutrient concentration allows for its use toestimate growing medium fertility status [19] Compared toall the other indices the trend for the changes in pH of thesolutions for all the treatments was different (Figure 1(a))
e pH of the solution rapidly declined within the first40min before steeply rising to reach a peak at the 8th hourfollowed by a steep fall at the 24th hour Overall there wereno clear differences in salinity TDS pH and EC of thesolutions for the SVB VTB DWB and the Bioc apart fromthe obvious fluctuations in the line graph for treatmentDWB According to Sizmur et al [18] the manifestation ofchemical sorption is attributed to ion exchange and nu-merous functional groups on the carbonaceous surface ofbiochar As such the fluctuations in the line graphs for theDWB in Figures 1(a)ndash1(d) can be ascribed to low chemical
activity in the deionized water as compared to the vermicast-inoculated biochar treatments e values of all the mea-sured water quality indices for the Pro-BX treatment werefound to be higher than the respective values for SVB VTBDWB and Bioc treatments However the differences beganto show after the 300th hour ese findings demonstratedthe slow release of nutrients from the biochar treatmentscompared to the Pro-BX Particularly the DWB seemed tobe the fastest in releasing its nutrients while the SVB and theBioc seemed to be intermediate It was noticed that therelease of materials into the solution and the pH fortreatment Pro-BX seemed to be generally more stable afterthe 350th hour of sampling compared to the othertreatments
e release of nitrate (NO3minus) into the deionized waterfrom the Pro-BX treatment was the fastest compared to allthe biochar treatments and was followed by a steep declineimmediately after 2 hr of submergence (Figure 2(a)) Afterthe 150th hour the amount of NO3minus released into the so-lution from the Pro-BX did not change However NO3minus
released into solution from the SVB DWB VTB and theBioc showed significant fluctuations throughout the sam-pling period which lasted for 591 hr (ca 246 days) efluctuations can be attributed to microbial and chemicalactivities such as bioconversion of N anion exchange andvolatilization but were not determined in the present studyA lag phase prior to the first 50th hour followed by a rapidincrease in ionic concentrations of K+ Na+ and Ca+2 in thesampled solution (Figures 2(b)ndash2(d)) was also observed econcentrations of K+ and Na+ in the sampled solutions fromall the treatments increased exponentially while that of the
Table 2 Mineral nutrient composition of the growing mediacomponents
Ca2+ seemed to have increased linearly as sampling timeprogressed Amongst the biochar treatments the highest K+
concentration was recorded by the DWB treatment and theleast was recorded by the Bioc treatment while the SVB andthe VTB treatments were in between and not different
Comparatively the release of K+ and Na+ into solutionfrom the Pro-BX was instant and consistently the least justlike the NO3minus is can be attributed to the highly solublenature of K and Na salts However the release of Na+ intosolution was not different amongst the four biochar treat-ments On the contrary the release of Ca2+ into solutionfrom the Pro-BX treatment was the fastest and the highestand was represented by a sigmoidal curve in Figure 2(c) eresult showed that the release of Ca2+ from the Pro-BXsteeply rose after the 100th hour of sampling before levellingoff Overall Ca2+ concentration of all the four biochartreatments fluctuatede release of Ca2+ was highest for theBioc treatment followed by the SVB then the DWB and the
VTB (Figure 2(c)) e fluctuations in the concentrations ofCa2+ released into solution from the biochar treatmentscould be ascribed to ionic exchange activities on the car-bonaceous surface of the biochar erefore the presentresults can be explained by possible modification and ac-tivation of the biochar when it was inoculated with vermicastor deionized water followed by an incubation period asreported by Sizmur et al [18] From Figures 2(a)ndash2(d) itseemed the concentrations of NO3minus K+ Ca2+ and Na+ fromeach of the biochar treatments will continue to rise if thesampling time was extended beyond the 591 hr of the nu-trient release study e variation in the trend of nutrientrelease from the different media treatments is an indicationof possible variations in nutrient availability for plant uptakeand utilization for growth and development
Chlorophyll fluorescence activity was used to assessphotosynthetic activities in Swiss chard cv Rhubarb chardgrown in different treatments It was found that the
Figure 1 Changes in pH total dissolved solids salinity and electric conductivity of solid vermicast-inoculated biochar (solid line greensquare) vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biocharalone (solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard errorbars
International Journal of Agronomy 5
maximum quantum yields also termed as efficiency ofphotosystem II (FvFm) for the Swiss chard plants rangedbetween 076 and 078 and were not significantly (Pgt 005)different between treatments (data not presented) Leafchlorophyll content estimated using the SPAD value of leafgreenness was differentially influenced by the differentmedium treatments Prior to the first harvest ie four weeksafter transplanting the SPAD value was significantly highestin plants grown in the treatment Pro-BX followed bytreatments SVB and VTB and lowest in treatments Bioc andDWB (Figure 3(a))
However there was a remarkable change in the extent towhich the treatments affected the SPAD value of leafgreenness at the second harvest at eight weeks after trans-planting Treatments SVB and VTB equally increased SPADvalue at the second harvest by ca 044-fold compared to thefirst harvest but was remarkably reduced in plants grown inthe Pro-BX by ca 038-fold It was noted that the change washowever moderate in Swiss chard plants grown in the DWBand the Bioc Leaf anthocyanin content was similar for all theplants irrespective of the medium treatment at the firstharvest (Figure 3(b)) At the second harvest only treatmentsVTB and SVB increased leaf anthocyanin contents by ca080- and 095-fold respectively ese findings indicatedthat leaf pigmentation was significantly influenced by VTB
and SVB compared to the other treatments is furtherconfirmed the slow release of nutrients from biochar in-oculated with vermicast
e number of Swiss chard green leaves and plant massdensity which indicate assimilate accumulation were notsignificantly (Pgt 005) different among the treatments andbetween the two harvest times (data not presented) How-ever other plant growth components such as plant heightstem diameter leaf fresh weight and total leaf area wereclearly affected (Figures 4(a)ndash4(d)) ese plant growthcomponents were significantly (Plt 005) increased bytreatment Pro-BX followed by treatments DWB and Biocand the lowest by treatments SVB and VTB at the firstharvest But this growth trend changed at the second harvest
Changes in plant height between the first and the secondharvests were prominent for VTB and SVB It was found thatplant height increased by approximately 203-fold for VTBand by 067-fold for SVB and did not significantly (Pgt 005)change for Bioc or DWB but significantly (Plt 005) reducedby ca 045-fold for Pro-BX Swiss chard plant stem diameterwas increased by approximately 166-fold for VTB and 059-fold for SVB while minor nonsignificant changes wererecorded for Bioc and DWBe Pro-BX on the other handsignificantly (Plt 005) reduced stem diameter by ca 047-fold at the second harvest e trend for both total leaf
Figure 2 Release of potassium sodium nitrate and calcium contents of solid vermicast-inoculated biochar (solid line green square)vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biochar alone(solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard error bars
6 International Journal of Agronomy
b bc bc
aC
C
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
50
100
150
200
250
Plan
t hei
ght (
cm)
PH1PH2
(a)
bcb
c c
a
BCBC
B
A
C
Bioc DWB SVB VTB Pro-BXTreatments
00
20
40
60
80
100
Stem
dia
met
er (m
m)
SD1SD2
(b)
b b bc
a
C CB
A
D
Bioc DWB SVB VTB Pro-BX
Tota
l lea
f fre
sh w
eigh
t (g
plan
t)
Treatments
00
50
100
150
200
250
LFW1LFW2
(c)
bbc
cd
a
BCD
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
150
300
450
600
750
Mea
n le
af ar
ea (c
m2 )
LA1LA2
(d)
Figure 4 Plant height (PH) stem diameter (SD) leaf area (LA) and total edible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculatedbiochar (SVB) vermicast tea-inoculated biochar (VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical lettersrepresent mean separation by the least significant difference (α 005) at the first (1) and the second (2) harvests respectively Vertical lineson bars represent standard error of the means
c c
b b
a
BB
A A
B
Bioc DWB SVB VTB Pro-BX
Leaf
gre
enne
ss (S
PAD
val
ue)
Treatments
00
100
200
300
400
500
600
LG1LG2
(a)
a aa a
aC C
A
B
C
Bioc DWB SVB VTB Pro-BXTreatments
00
10
20
30
40
50
60
Ant
hocy
anin
cont
ent (
ACI
)
AC1AC2
(b)
Figure 3 Leaf greenness and anthocyanin content of Swiss chard (Beta vulgaris subsp vulgaris) cv Rhubarb chard as affected by biocharalone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculated biochar (SVB) vermicast tea-inoculated biochar(VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical letters represent mean separation by the least significantdifference (α 005) at the first (1) and the second (2) harvests respectively Vertical lines on bars represent standard error of the means
International Journal of Agronomy 7
surface area and fresh weight at first harvest was Pro-BXgtBiocgtDWB SVBgtVTB (Figures 4(c)ndash4(d)) istrend drastically changed at the second harvest e onlytreatment that increased total leaf area and leaf fresh weightat the second harvest was VTB ie by approximately 102-and 188-fold compared to those at the first harvest On thecontrary total leaf area was significantly (Plt 005) reducedby approximately 042-fold for SVB 074-fold for DWB069-fold for Bioc and 090-fold for Pro-BX (Figure 4(c))while leaf fresh weight was significantly reduced by ap-proximately 033-fold for DWB 028-fold for Bioc and 070-fold for Pro-BX but was not altered by SVB (Figure 4(d)) atthe second harvest as compared to the first harvest A 2-dimensional biplot principal component analysis (PCA) wasused to further explain relationships between the treatmentsand the growth components e PCA biplot explained 92of the variations in the dataset for the plant growth com-ponents as affected by the media treatments Pro-BX BiocDWB SVB and VTB (Figure 5)
ere were distinct differences in the media except thatBioc and DWB were similar and both appeared in the samequadrant on the PCA biplot e plant growth componentsat the first harvest can be found in the first quadrant with thePro-BX treatment is suggested that the PCA plot agreedwith Figures 3 and 4 that the Pro-BX treatment significantlyincreased plant growth components at the first harvest BothSVB and VTB can be found in quadrant 2 of the PCA biplotwith the plant growth components at the second harvestelocation of SVB relative to VTB and the plant growthcomponents suggested that the latter was more effective ininfluencing the plant growth components Neither Bioc norDWB influenced plant growth ese showed that the effectof treatment VTB which was not apparent in the first fourweeks became obvious Additionally VTB recorded thehighest effect on the Swiss chard plant growth componentsat the second harvest us the VTB treatment delayed therelease of nutrients but was made available eventually toincrease the Swiss chard plant growth and yield during theregrowth phase after the first harvest ese findings can beconfirmed by the results of the nutrient release experimentsin Figures 1 and 2 as shown on the PCA biplot
In conclusion the study confirmed that inoculation ofbiochar with vermicast can increase its adsorption capacityfor nutrients which will subsequently be released slowly toplants for root uptake and plant utilization It is evident fromthe present study that the nutrient release rate of inoculatedbiochar is initially slow Vermicast tea-inoculated biocharand solid vermicast-inoculated biochar have similar nutrientrelease patterns and proved to be highly activated Inocu-lated biochar characteristically releases nutrients slowly witha long-lasting impact on growing media environment andultimately plant productivity Comparatively vermicast teawas the most effective in inoculation of the biochar and assuch it was the most efficacious under the conditions of thisstudy Future investigation should consider microbial ac-tivities in these media
e nutrient release plant nutrient uptake and plant growthdata used to support the findings of this study are includedwithin the supplementary information files
Conflicts of Interest
e authors declare that they have no conflicts of interest
Acknowledgments
e authors wish to thank Dr Samuel Asiedu for his as-sistance during the experimentation and Dr NancyMacLean for her guidance on performing the statisticalanalysis However the authors wish to thank Proton PowerInc Tennessee USA for the donation of the biochar
Supplementary Materials
e supplementary files with data showed in S1ndashS11 wereused to report the outcomes of the study e commonacronyms used were as follows Bioc biochar aloneDWB deionized water-inoculated biochar SVB solidvermicast-inoculated biochar VTB vermicast tea-inocu-lated biochar Pro-BXPromix-BX soilless medium aloneS1 the data for the various growing medium salinity contentduring the nutrient release studies S2 the data for thechanges in electric conductivity of the solution when theindividual media were submerged in deionized water S3 thechanges in the acidity level (ie pH) of the solution when the
Figure 5 A two-dimensional principal component analysis biplotshowing relationships among media treatments as active variablesand plant growth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content (AC)plant height (PH) stem diameter (SD) leaf area (LA) and totaledible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc)deionized water-inoculated biochar (DWB) solid vermicast-in-oculated biochar (SVB) vermicast tea-inoculated biochar (VTB)and Promix-BX alone (Pro-BX) at the first (1) and the second (2)harvests respectively
8 International Journal of Agronomy
individual media were submerged in deionized water S4 thetotal dissolved solids in solution when the individual mediawere submerged in deionized water S5 S6 S7 and S8 theconcentrations of calcium potassium nitrate and sodiumions in solution when the individual media were submergedin the deionized water S9 the data for a two-dimensionalprincipal component analysis biplot showing relationshipsamong media treatments as active variables and plantgrowth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content(AC) plant height (PH) stem diameter (SD) leaf area (LA)and total edible leaf fresh weight (LFW) of Swiss chard (Betavulgaris subsp vulgaris) cv Rhubarb chard as affected by thegrowing medium treatments at the first (1) and the second(2) harvests respectively S10 the data for the mineralnutrient composition of the individual growing media be-fore the beginning of the nutrient release studies S11 thedata for plant growth and yield components as affected bythe individual growing medium treatments (SupplementaryMaterials)
References
[1] G Agegnehu A K Srivastava and M I Bird ldquoe role ofbiochar and biochar-compost in improving soil quality andcrop performance a reviewrdquo Applied Soil Ecology vol 119pp 156ndash170 2017
[2] R Xiao M K Awasthi R Li et al ldquoRecent developments inbiochar utilization as an additive in organic solid wastecomposting a reviewrdquo Bioresource Technology vol 246pp 203ndash213 2017
[3] Y Yuan H Chen W Yuan D Williams J T Walker andW Shi ldquoIs biochar-manure co-compost a better solution forsoil health improvement and N2O emissions mitigationrdquo SoilBiology and Biochemistry vol 113 pp 14ndash25 2017
[4] A Grewal L Abbey and L R Gunupuru ldquoProductionprospects and potential application of pyroligneous acid inagriculturerdquo Journal of Analytical and Applied Pyrolysisvol 135 pp 152ndash159 2018
[5] G Agegnehu A M Bass P N Nelson B MuirheadG Wright and M I Bird ldquoBiochar and biochar-compost assoil amendments effects on peanut yield soil properties andgreenhouse gas emissions in tropical North QueenslandAustraliardquo Agriculture Ecosystems amp Environment vol 213pp 72ndash85 2015
[6] N Khan I Clark M A Sanchez-Monedero et al ldquoPhysicaland chemical properties of biochars co-composted withbiowastes and incubated with a chicken litter compostrdquoChemosphere vol 142 pp 14ndash23 2016
[7] F Rees C Germain T Sterckeman and J-L Morel ldquoPlantgrowth and metal uptake by a non-hyperaccumulating species(Lolium perenne) and a Cd-Zn hyperaccumulator (Noccaeacaerulescens) in contaminated soils amended with biocharrdquoPlant and Soil vol 395 no 1-2 pp 57ndash73 2015
[8] J Pietikainen O Kiikkila andH Fritze ldquoCharcoal as a habitatfor microbes and its effect on the microbial community of theunderlying humusrdquo Oikos vol 89 no 2 pp 231ndash242 2000
[9] L Beesley E Moreno-Jimenez and J L Gomez-Eyles ldquoEffectsof biochar and greenwaste compost amendments on mobilitybioavailability and toxicity of inorganic and organic con-taminants in a multi-element polluted soilrdquo EnvironmentalPollution vol 158 no 6 pp 2282ndash2287 2010
[10] N Hagemann K Spokas H-P Schmidt R Kagi M Bohlerand T Bucheli ldquoActivated carbon biochar and charcoallinkages and synergies across pyrogenic carbonrsquos ABCsrdquoWater vol 10 no 2 pp 182ndash201 2018
[11] C Sreenivas S Muralidhar and M S Rao ldquoVermicompost aviable component of IPNSS in nitrogen nutrition of ridgegourdrdquo Annals of Agricultural Research vol 21 no 1pp 108ndash113 2000
[12] AOAC Protein (Crude) in Animal Feed Combustion MethodAOAC Official Method 99003 Official Methods of AnalysisAssociation of Official Analytical Chemists GaithersburgMD USA 17th edition 2003
[13] AOAC Metals and Other Elements in Plants and Pet FoodsInductively Coupled Plasma Spectroscopic Method AOACOfficial Method 96808 Official Methods of Analysis Asso-ciation of Official Analytical Chemists Gaithersburg MDUSA 17th edition 2003
[14] L Abbey S A Rao L N Hodgins and F Briet ldquoDrying andrehydration of vermicasts do not affect nutrient bioavailabilityand seedling growthrdquo American Journal of Plant Nutritionand Fertilization Technology vol 3 no 1 pp 12ndash21 2013
[15] A E Louw-Gaume I M Rao A J Gaume and E FrossardldquoA comparative study on plant growth and root plasticityresponses of two Brachiaria forage grasses grown in nutrientsolution at low and high phosphorus supplyrdquo Plant and Soilvol 328 no 1-2 pp 155ndash164 2010
[16] K Maxwell and G N Johnson ldquoChlorophyll fluorescence-apractical guiderdquo Journal of Experimental Botany vol 51no 345 pp 659ndash668 2000
[17] H Wu C Lai G Zeng et al ldquoe interactions of compostingand biochar and their implications for soil amendment andpollution remediation a reviewrdquo Critical Reviews in Bio-technology vol 37 no 6 pp 754ndash764 2016
[18] T Sizmur T Fresno G Akgul H Frost and E Moreno-Jimenez ldquoBiochar modification to enhance sorption of in-organics from waterrdquo Bioresource Technology vol 246pp 34ndash47 2017
[19] L Martınez-Suller G Provolo D Brennan et al ldquoA note onthe estimation of nutrient value of cattle slurry using easilydetermined physical and chemical parametersrdquo Irish Journalof Agricultural and Food Resarch vol 49 pp 93ndash97 2010
International Journal of Agronomy 9
Ca2+ seemed to have increased linearly as sampling timeprogressed Amongst the biochar treatments the highest K+
concentration was recorded by the DWB treatment and theleast was recorded by the Bioc treatment while the SVB andthe VTB treatments were in between and not different
Comparatively the release of K+ and Na+ into solutionfrom the Pro-BX was instant and consistently the least justlike the NO3minus is can be attributed to the highly solublenature of K and Na salts However the release of Na+ intosolution was not different amongst the four biochar treat-ments On the contrary the release of Ca2+ into solutionfrom the Pro-BX treatment was the fastest and the highestand was represented by a sigmoidal curve in Figure 2(c) eresult showed that the release of Ca2+ from the Pro-BXsteeply rose after the 100th hour of sampling before levellingoff Overall Ca2+ concentration of all the four biochartreatments fluctuatede release of Ca2+ was highest for theBioc treatment followed by the SVB then the DWB and the
VTB (Figure 2(c)) e fluctuations in the concentrations ofCa2+ released into solution from the biochar treatmentscould be ascribed to ionic exchange activities on the car-bonaceous surface of the biochar erefore the presentresults can be explained by possible modification and ac-tivation of the biochar when it was inoculated with vermicastor deionized water followed by an incubation period asreported by Sizmur et al [18] From Figures 2(a)ndash2(d) itseemed the concentrations of NO3minus K+ Ca2+ and Na+ fromeach of the biochar treatments will continue to rise if thesampling time was extended beyond the 591 hr of the nu-trient release study e variation in the trend of nutrientrelease from the different media treatments is an indicationof possible variations in nutrient availability for plant uptakeand utilization for growth and development
Chlorophyll fluorescence activity was used to assessphotosynthetic activities in Swiss chard cv Rhubarb chardgrown in different treatments It was found that the
Figure 1 Changes in pH total dissolved solids salinity and electric conductivity of solid vermicast-inoculated biochar (solid line greensquare) vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biocharalone (solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard errorbars
International Journal of Agronomy 5
maximum quantum yields also termed as efficiency ofphotosystem II (FvFm) for the Swiss chard plants rangedbetween 076 and 078 and were not significantly (Pgt 005)different between treatments (data not presented) Leafchlorophyll content estimated using the SPAD value of leafgreenness was differentially influenced by the differentmedium treatments Prior to the first harvest ie four weeksafter transplanting the SPAD value was significantly highestin plants grown in the treatment Pro-BX followed bytreatments SVB and VTB and lowest in treatments Bioc andDWB (Figure 3(a))
However there was a remarkable change in the extent towhich the treatments affected the SPAD value of leafgreenness at the second harvest at eight weeks after trans-planting Treatments SVB and VTB equally increased SPADvalue at the second harvest by ca 044-fold compared to thefirst harvest but was remarkably reduced in plants grown inthe Pro-BX by ca 038-fold It was noted that the change washowever moderate in Swiss chard plants grown in the DWBand the Bioc Leaf anthocyanin content was similar for all theplants irrespective of the medium treatment at the firstharvest (Figure 3(b)) At the second harvest only treatmentsVTB and SVB increased leaf anthocyanin contents by ca080- and 095-fold respectively ese findings indicatedthat leaf pigmentation was significantly influenced by VTB
and SVB compared to the other treatments is furtherconfirmed the slow release of nutrients from biochar in-oculated with vermicast
e number of Swiss chard green leaves and plant massdensity which indicate assimilate accumulation were notsignificantly (Pgt 005) different among the treatments andbetween the two harvest times (data not presented) How-ever other plant growth components such as plant heightstem diameter leaf fresh weight and total leaf area wereclearly affected (Figures 4(a)ndash4(d)) ese plant growthcomponents were significantly (Plt 005) increased bytreatment Pro-BX followed by treatments DWB and Biocand the lowest by treatments SVB and VTB at the firstharvest But this growth trend changed at the second harvest
Changes in plant height between the first and the secondharvests were prominent for VTB and SVB It was found thatplant height increased by approximately 203-fold for VTBand by 067-fold for SVB and did not significantly (Pgt 005)change for Bioc or DWB but significantly (Plt 005) reducedby ca 045-fold for Pro-BX Swiss chard plant stem diameterwas increased by approximately 166-fold for VTB and 059-fold for SVB while minor nonsignificant changes wererecorded for Bioc and DWBe Pro-BX on the other handsignificantly (Plt 005) reduced stem diameter by ca 047-fold at the second harvest e trend for both total leaf
Figure 2 Release of potassium sodium nitrate and calcium contents of solid vermicast-inoculated biochar (solid line green square)vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biochar alone(solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard error bars
6 International Journal of Agronomy
b bc bc
aC
C
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
50
100
150
200
250
Plan
t hei
ght (
cm)
PH1PH2
(a)
bcb
c c
a
BCBC
B
A
C
Bioc DWB SVB VTB Pro-BXTreatments
00
20
40
60
80
100
Stem
dia
met
er (m
m)
SD1SD2
(b)
b b bc
a
C CB
A
D
Bioc DWB SVB VTB Pro-BX
Tota
l lea
f fre
sh w
eigh
t (g
plan
t)
Treatments
00
50
100
150
200
250
LFW1LFW2
(c)
bbc
cd
a
BCD
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
150
300
450
600
750
Mea
n le
af ar
ea (c
m2 )
LA1LA2
(d)
Figure 4 Plant height (PH) stem diameter (SD) leaf area (LA) and total edible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculatedbiochar (SVB) vermicast tea-inoculated biochar (VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical lettersrepresent mean separation by the least significant difference (α 005) at the first (1) and the second (2) harvests respectively Vertical lineson bars represent standard error of the means
c c
b b
a
BB
A A
B
Bioc DWB SVB VTB Pro-BX
Leaf
gre
enne
ss (S
PAD
val
ue)
Treatments
00
100
200
300
400
500
600
LG1LG2
(a)
a aa a
aC C
A
B
C
Bioc DWB SVB VTB Pro-BXTreatments
00
10
20
30
40
50
60
Ant
hocy
anin
cont
ent (
ACI
)
AC1AC2
(b)
Figure 3 Leaf greenness and anthocyanin content of Swiss chard (Beta vulgaris subsp vulgaris) cv Rhubarb chard as affected by biocharalone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculated biochar (SVB) vermicast tea-inoculated biochar(VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical letters represent mean separation by the least significantdifference (α 005) at the first (1) and the second (2) harvests respectively Vertical lines on bars represent standard error of the means
International Journal of Agronomy 7
surface area and fresh weight at first harvest was Pro-BXgtBiocgtDWB SVBgtVTB (Figures 4(c)ndash4(d)) istrend drastically changed at the second harvest e onlytreatment that increased total leaf area and leaf fresh weightat the second harvest was VTB ie by approximately 102-and 188-fold compared to those at the first harvest On thecontrary total leaf area was significantly (Plt 005) reducedby approximately 042-fold for SVB 074-fold for DWB069-fold for Bioc and 090-fold for Pro-BX (Figure 4(c))while leaf fresh weight was significantly reduced by ap-proximately 033-fold for DWB 028-fold for Bioc and 070-fold for Pro-BX but was not altered by SVB (Figure 4(d)) atthe second harvest as compared to the first harvest A 2-dimensional biplot principal component analysis (PCA) wasused to further explain relationships between the treatmentsand the growth components e PCA biplot explained 92of the variations in the dataset for the plant growth com-ponents as affected by the media treatments Pro-BX BiocDWB SVB and VTB (Figure 5)
ere were distinct differences in the media except thatBioc and DWB were similar and both appeared in the samequadrant on the PCA biplot e plant growth componentsat the first harvest can be found in the first quadrant with thePro-BX treatment is suggested that the PCA plot agreedwith Figures 3 and 4 that the Pro-BX treatment significantlyincreased plant growth components at the first harvest BothSVB and VTB can be found in quadrant 2 of the PCA biplotwith the plant growth components at the second harvestelocation of SVB relative to VTB and the plant growthcomponents suggested that the latter was more effective ininfluencing the plant growth components Neither Bioc norDWB influenced plant growth ese showed that the effectof treatment VTB which was not apparent in the first fourweeks became obvious Additionally VTB recorded thehighest effect on the Swiss chard plant growth componentsat the second harvest us the VTB treatment delayed therelease of nutrients but was made available eventually toincrease the Swiss chard plant growth and yield during theregrowth phase after the first harvest ese findings can beconfirmed by the results of the nutrient release experimentsin Figures 1 and 2 as shown on the PCA biplot
In conclusion the study confirmed that inoculation ofbiochar with vermicast can increase its adsorption capacityfor nutrients which will subsequently be released slowly toplants for root uptake and plant utilization It is evident fromthe present study that the nutrient release rate of inoculatedbiochar is initially slow Vermicast tea-inoculated biocharand solid vermicast-inoculated biochar have similar nutrientrelease patterns and proved to be highly activated Inocu-lated biochar characteristically releases nutrients slowly witha long-lasting impact on growing media environment andultimately plant productivity Comparatively vermicast teawas the most effective in inoculation of the biochar and assuch it was the most efficacious under the conditions of thisstudy Future investigation should consider microbial ac-tivities in these media
e nutrient release plant nutrient uptake and plant growthdata used to support the findings of this study are includedwithin the supplementary information files
Conflicts of Interest
e authors declare that they have no conflicts of interest
Acknowledgments
e authors wish to thank Dr Samuel Asiedu for his as-sistance during the experimentation and Dr NancyMacLean for her guidance on performing the statisticalanalysis However the authors wish to thank Proton PowerInc Tennessee USA for the donation of the biochar
Supplementary Materials
e supplementary files with data showed in S1ndashS11 wereused to report the outcomes of the study e commonacronyms used were as follows Bioc biochar aloneDWB deionized water-inoculated biochar SVB solidvermicast-inoculated biochar VTB vermicast tea-inocu-lated biochar Pro-BXPromix-BX soilless medium aloneS1 the data for the various growing medium salinity contentduring the nutrient release studies S2 the data for thechanges in electric conductivity of the solution when theindividual media were submerged in deionized water S3 thechanges in the acidity level (ie pH) of the solution when the
Figure 5 A two-dimensional principal component analysis biplotshowing relationships among media treatments as active variablesand plant growth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content (AC)plant height (PH) stem diameter (SD) leaf area (LA) and totaledible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc)deionized water-inoculated biochar (DWB) solid vermicast-in-oculated biochar (SVB) vermicast tea-inoculated biochar (VTB)and Promix-BX alone (Pro-BX) at the first (1) and the second (2)harvests respectively
8 International Journal of Agronomy
individual media were submerged in deionized water S4 thetotal dissolved solids in solution when the individual mediawere submerged in deionized water S5 S6 S7 and S8 theconcentrations of calcium potassium nitrate and sodiumions in solution when the individual media were submergedin the deionized water S9 the data for a two-dimensionalprincipal component analysis biplot showing relationshipsamong media treatments as active variables and plantgrowth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content(AC) plant height (PH) stem diameter (SD) leaf area (LA)and total edible leaf fresh weight (LFW) of Swiss chard (Betavulgaris subsp vulgaris) cv Rhubarb chard as affected by thegrowing medium treatments at the first (1) and the second(2) harvests respectively S10 the data for the mineralnutrient composition of the individual growing media be-fore the beginning of the nutrient release studies S11 thedata for plant growth and yield components as affected bythe individual growing medium treatments (SupplementaryMaterials)
References
[1] G Agegnehu A K Srivastava and M I Bird ldquoe role ofbiochar and biochar-compost in improving soil quality andcrop performance a reviewrdquo Applied Soil Ecology vol 119pp 156ndash170 2017
[2] R Xiao M K Awasthi R Li et al ldquoRecent developments inbiochar utilization as an additive in organic solid wastecomposting a reviewrdquo Bioresource Technology vol 246pp 203ndash213 2017
[3] Y Yuan H Chen W Yuan D Williams J T Walker andW Shi ldquoIs biochar-manure co-compost a better solution forsoil health improvement and N2O emissions mitigationrdquo SoilBiology and Biochemistry vol 113 pp 14ndash25 2017
[4] A Grewal L Abbey and L R Gunupuru ldquoProductionprospects and potential application of pyroligneous acid inagriculturerdquo Journal of Analytical and Applied Pyrolysisvol 135 pp 152ndash159 2018
[5] G Agegnehu A M Bass P N Nelson B MuirheadG Wright and M I Bird ldquoBiochar and biochar-compost assoil amendments effects on peanut yield soil properties andgreenhouse gas emissions in tropical North QueenslandAustraliardquo Agriculture Ecosystems amp Environment vol 213pp 72ndash85 2015
[6] N Khan I Clark M A Sanchez-Monedero et al ldquoPhysicaland chemical properties of biochars co-composted withbiowastes and incubated with a chicken litter compostrdquoChemosphere vol 142 pp 14ndash23 2016
[7] F Rees C Germain T Sterckeman and J-L Morel ldquoPlantgrowth and metal uptake by a non-hyperaccumulating species(Lolium perenne) and a Cd-Zn hyperaccumulator (Noccaeacaerulescens) in contaminated soils amended with biocharrdquoPlant and Soil vol 395 no 1-2 pp 57ndash73 2015
[8] J Pietikainen O Kiikkila andH Fritze ldquoCharcoal as a habitatfor microbes and its effect on the microbial community of theunderlying humusrdquo Oikos vol 89 no 2 pp 231ndash242 2000
[9] L Beesley E Moreno-Jimenez and J L Gomez-Eyles ldquoEffectsof biochar and greenwaste compost amendments on mobilitybioavailability and toxicity of inorganic and organic con-taminants in a multi-element polluted soilrdquo EnvironmentalPollution vol 158 no 6 pp 2282ndash2287 2010
[10] N Hagemann K Spokas H-P Schmidt R Kagi M Bohlerand T Bucheli ldquoActivated carbon biochar and charcoallinkages and synergies across pyrogenic carbonrsquos ABCsrdquoWater vol 10 no 2 pp 182ndash201 2018
[11] C Sreenivas S Muralidhar and M S Rao ldquoVermicompost aviable component of IPNSS in nitrogen nutrition of ridgegourdrdquo Annals of Agricultural Research vol 21 no 1pp 108ndash113 2000
[12] AOAC Protein (Crude) in Animal Feed Combustion MethodAOAC Official Method 99003 Official Methods of AnalysisAssociation of Official Analytical Chemists GaithersburgMD USA 17th edition 2003
[13] AOAC Metals and Other Elements in Plants and Pet FoodsInductively Coupled Plasma Spectroscopic Method AOACOfficial Method 96808 Official Methods of Analysis Asso-ciation of Official Analytical Chemists Gaithersburg MDUSA 17th edition 2003
[14] L Abbey S A Rao L N Hodgins and F Briet ldquoDrying andrehydration of vermicasts do not affect nutrient bioavailabilityand seedling growthrdquo American Journal of Plant Nutritionand Fertilization Technology vol 3 no 1 pp 12ndash21 2013
[15] A E Louw-Gaume I M Rao A J Gaume and E FrossardldquoA comparative study on plant growth and root plasticityresponses of two Brachiaria forage grasses grown in nutrientsolution at low and high phosphorus supplyrdquo Plant and Soilvol 328 no 1-2 pp 155ndash164 2010
[16] K Maxwell and G N Johnson ldquoChlorophyll fluorescence-apractical guiderdquo Journal of Experimental Botany vol 51no 345 pp 659ndash668 2000
[17] H Wu C Lai G Zeng et al ldquoe interactions of compostingand biochar and their implications for soil amendment andpollution remediation a reviewrdquo Critical Reviews in Bio-technology vol 37 no 6 pp 754ndash764 2016
[18] T Sizmur T Fresno G Akgul H Frost and E Moreno-Jimenez ldquoBiochar modification to enhance sorption of in-organics from waterrdquo Bioresource Technology vol 246pp 34ndash47 2017
[19] L Martınez-Suller G Provolo D Brennan et al ldquoA note onthe estimation of nutrient value of cattle slurry using easilydetermined physical and chemical parametersrdquo Irish Journalof Agricultural and Food Resarch vol 49 pp 93ndash97 2010
International Journal of Agronomy 9
maximum quantum yields also termed as efficiency ofphotosystem II (FvFm) for the Swiss chard plants rangedbetween 076 and 078 and were not significantly (Pgt 005)different between treatments (data not presented) Leafchlorophyll content estimated using the SPAD value of leafgreenness was differentially influenced by the differentmedium treatments Prior to the first harvest ie four weeksafter transplanting the SPAD value was significantly highestin plants grown in the treatment Pro-BX followed bytreatments SVB and VTB and lowest in treatments Bioc andDWB (Figure 3(a))
However there was a remarkable change in the extent towhich the treatments affected the SPAD value of leafgreenness at the second harvest at eight weeks after trans-planting Treatments SVB and VTB equally increased SPADvalue at the second harvest by ca 044-fold compared to thefirst harvest but was remarkably reduced in plants grown inthe Pro-BX by ca 038-fold It was noted that the change washowever moderate in Swiss chard plants grown in the DWBand the Bioc Leaf anthocyanin content was similar for all theplants irrespective of the medium treatment at the firstharvest (Figure 3(b)) At the second harvest only treatmentsVTB and SVB increased leaf anthocyanin contents by ca080- and 095-fold respectively ese findings indicatedthat leaf pigmentation was significantly influenced by VTB
and SVB compared to the other treatments is furtherconfirmed the slow release of nutrients from biochar in-oculated with vermicast
e number of Swiss chard green leaves and plant massdensity which indicate assimilate accumulation were notsignificantly (Pgt 005) different among the treatments andbetween the two harvest times (data not presented) How-ever other plant growth components such as plant heightstem diameter leaf fresh weight and total leaf area wereclearly affected (Figures 4(a)ndash4(d)) ese plant growthcomponents were significantly (Plt 005) increased bytreatment Pro-BX followed by treatments DWB and Biocand the lowest by treatments SVB and VTB at the firstharvest But this growth trend changed at the second harvest
Changes in plant height between the first and the secondharvests were prominent for VTB and SVB It was found thatplant height increased by approximately 203-fold for VTBand by 067-fold for SVB and did not significantly (Pgt 005)change for Bioc or DWB but significantly (Plt 005) reducedby ca 045-fold for Pro-BX Swiss chard plant stem diameterwas increased by approximately 166-fold for VTB and 059-fold for SVB while minor nonsignificant changes wererecorded for Bioc and DWBe Pro-BX on the other handsignificantly (Plt 005) reduced stem diameter by ca 047-fold at the second harvest e trend for both total leaf
Figure 2 Release of potassium sodium nitrate and calcium contents of solid vermicast-inoculated biochar (solid line green square)vermicast tea-inoculated biochar (solid line red rhombus) deionized water-inoculated biochar (solid line blue triangle) biochar alone(solid line black round) and Promix-BX alone (broken line brown dash) in deionized water Vertical lines represent standard error bars
6 International Journal of Agronomy
b bc bc
aC
C
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
50
100
150
200
250
Plan
t hei
ght (
cm)
PH1PH2
(a)
bcb
c c
a
BCBC
B
A
C
Bioc DWB SVB VTB Pro-BXTreatments
00
20
40
60
80
100
Stem
dia
met
er (m
m)
SD1SD2
(b)
b b bc
a
C CB
A
D
Bioc DWB SVB VTB Pro-BX
Tota
l lea
f fre
sh w
eigh
t (g
plan
t)
Treatments
00
50
100
150
200
250
LFW1LFW2
(c)
bbc
cd
a
BCD
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
150
300
450
600
750
Mea
n le
af ar
ea (c
m2 )
LA1LA2
(d)
Figure 4 Plant height (PH) stem diameter (SD) leaf area (LA) and total edible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculatedbiochar (SVB) vermicast tea-inoculated biochar (VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical lettersrepresent mean separation by the least significant difference (α 005) at the first (1) and the second (2) harvests respectively Vertical lineson bars represent standard error of the means
c c
b b
a
BB
A A
B
Bioc DWB SVB VTB Pro-BX
Leaf
gre
enne
ss (S
PAD
val
ue)
Treatments
00
100
200
300
400
500
600
LG1LG2
(a)
a aa a
aC C
A
B
C
Bioc DWB SVB VTB Pro-BXTreatments
00
10
20
30
40
50
60
Ant
hocy
anin
cont
ent (
ACI
)
AC1AC2
(b)
Figure 3 Leaf greenness and anthocyanin content of Swiss chard (Beta vulgaris subsp vulgaris) cv Rhubarb chard as affected by biocharalone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculated biochar (SVB) vermicast tea-inoculated biochar(VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical letters represent mean separation by the least significantdifference (α 005) at the first (1) and the second (2) harvests respectively Vertical lines on bars represent standard error of the means
International Journal of Agronomy 7
surface area and fresh weight at first harvest was Pro-BXgtBiocgtDWB SVBgtVTB (Figures 4(c)ndash4(d)) istrend drastically changed at the second harvest e onlytreatment that increased total leaf area and leaf fresh weightat the second harvest was VTB ie by approximately 102-and 188-fold compared to those at the first harvest On thecontrary total leaf area was significantly (Plt 005) reducedby approximately 042-fold for SVB 074-fold for DWB069-fold for Bioc and 090-fold for Pro-BX (Figure 4(c))while leaf fresh weight was significantly reduced by ap-proximately 033-fold for DWB 028-fold for Bioc and 070-fold for Pro-BX but was not altered by SVB (Figure 4(d)) atthe second harvest as compared to the first harvest A 2-dimensional biplot principal component analysis (PCA) wasused to further explain relationships between the treatmentsand the growth components e PCA biplot explained 92of the variations in the dataset for the plant growth com-ponents as affected by the media treatments Pro-BX BiocDWB SVB and VTB (Figure 5)
ere were distinct differences in the media except thatBioc and DWB were similar and both appeared in the samequadrant on the PCA biplot e plant growth componentsat the first harvest can be found in the first quadrant with thePro-BX treatment is suggested that the PCA plot agreedwith Figures 3 and 4 that the Pro-BX treatment significantlyincreased plant growth components at the first harvest BothSVB and VTB can be found in quadrant 2 of the PCA biplotwith the plant growth components at the second harvestelocation of SVB relative to VTB and the plant growthcomponents suggested that the latter was more effective ininfluencing the plant growth components Neither Bioc norDWB influenced plant growth ese showed that the effectof treatment VTB which was not apparent in the first fourweeks became obvious Additionally VTB recorded thehighest effect on the Swiss chard plant growth componentsat the second harvest us the VTB treatment delayed therelease of nutrients but was made available eventually toincrease the Swiss chard plant growth and yield during theregrowth phase after the first harvest ese findings can beconfirmed by the results of the nutrient release experimentsin Figures 1 and 2 as shown on the PCA biplot
In conclusion the study confirmed that inoculation ofbiochar with vermicast can increase its adsorption capacityfor nutrients which will subsequently be released slowly toplants for root uptake and plant utilization It is evident fromthe present study that the nutrient release rate of inoculatedbiochar is initially slow Vermicast tea-inoculated biocharand solid vermicast-inoculated biochar have similar nutrientrelease patterns and proved to be highly activated Inocu-lated biochar characteristically releases nutrients slowly witha long-lasting impact on growing media environment andultimately plant productivity Comparatively vermicast teawas the most effective in inoculation of the biochar and assuch it was the most efficacious under the conditions of thisstudy Future investigation should consider microbial ac-tivities in these media
e nutrient release plant nutrient uptake and plant growthdata used to support the findings of this study are includedwithin the supplementary information files
Conflicts of Interest
e authors declare that they have no conflicts of interest
Acknowledgments
e authors wish to thank Dr Samuel Asiedu for his as-sistance during the experimentation and Dr NancyMacLean for her guidance on performing the statisticalanalysis However the authors wish to thank Proton PowerInc Tennessee USA for the donation of the biochar
Supplementary Materials
e supplementary files with data showed in S1ndashS11 wereused to report the outcomes of the study e commonacronyms used were as follows Bioc biochar aloneDWB deionized water-inoculated biochar SVB solidvermicast-inoculated biochar VTB vermicast tea-inocu-lated biochar Pro-BXPromix-BX soilless medium aloneS1 the data for the various growing medium salinity contentduring the nutrient release studies S2 the data for thechanges in electric conductivity of the solution when theindividual media were submerged in deionized water S3 thechanges in the acidity level (ie pH) of the solution when the
Figure 5 A two-dimensional principal component analysis biplotshowing relationships among media treatments as active variablesand plant growth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content (AC)plant height (PH) stem diameter (SD) leaf area (LA) and totaledible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc)deionized water-inoculated biochar (DWB) solid vermicast-in-oculated biochar (SVB) vermicast tea-inoculated biochar (VTB)and Promix-BX alone (Pro-BX) at the first (1) and the second (2)harvests respectively
8 International Journal of Agronomy
individual media were submerged in deionized water S4 thetotal dissolved solids in solution when the individual mediawere submerged in deionized water S5 S6 S7 and S8 theconcentrations of calcium potassium nitrate and sodiumions in solution when the individual media were submergedin the deionized water S9 the data for a two-dimensionalprincipal component analysis biplot showing relationshipsamong media treatments as active variables and plantgrowth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content(AC) plant height (PH) stem diameter (SD) leaf area (LA)and total edible leaf fresh weight (LFW) of Swiss chard (Betavulgaris subsp vulgaris) cv Rhubarb chard as affected by thegrowing medium treatments at the first (1) and the second(2) harvests respectively S10 the data for the mineralnutrient composition of the individual growing media be-fore the beginning of the nutrient release studies S11 thedata for plant growth and yield components as affected bythe individual growing medium treatments (SupplementaryMaterials)
References
[1] G Agegnehu A K Srivastava and M I Bird ldquoe role ofbiochar and biochar-compost in improving soil quality andcrop performance a reviewrdquo Applied Soil Ecology vol 119pp 156ndash170 2017
[2] R Xiao M K Awasthi R Li et al ldquoRecent developments inbiochar utilization as an additive in organic solid wastecomposting a reviewrdquo Bioresource Technology vol 246pp 203ndash213 2017
[3] Y Yuan H Chen W Yuan D Williams J T Walker andW Shi ldquoIs biochar-manure co-compost a better solution forsoil health improvement and N2O emissions mitigationrdquo SoilBiology and Biochemistry vol 113 pp 14ndash25 2017
[4] A Grewal L Abbey and L R Gunupuru ldquoProductionprospects and potential application of pyroligneous acid inagriculturerdquo Journal of Analytical and Applied Pyrolysisvol 135 pp 152ndash159 2018
[5] G Agegnehu A M Bass P N Nelson B MuirheadG Wright and M I Bird ldquoBiochar and biochar-compost assoil amendments effects on peanut yield soil properties andgreenhouse gas emissions in tropical North QueenslandAustraliardquo Agriculture Ecosystems amp Environment vol 213pp 72ndash85 2015
[6] N Khan I Clark M A Sanchez-Monedero et al ldquoPhysicaland chemical properties of biochars co-composted withbiowastes and incubated with a chicken litter compostrdquoChemosphere vol 142 pp 14ndash23 2016
[7] F Rees C Germain T Sterckeman and J-L Morel ldquoPlantgrowth and metal uptake by a non-hyperaccumulating species(Lolium perenne) and a Cd-Zn hyperaccumulator (Noccaeacaerulescens) in contaminated soils amended with biocharrdquoPlant and Soil vol 395 no 1-2 pp 57ndash73 2015
[8] J Pietikainen O Kiikkila andH Fritze ldquoCharcoal as a habitatfor microbes and its effect on the microbial community of theunderlying humusrdquo Oikos vol 89 no 2 pp 231ndash242 2000
[9] L Beesley E Moreno-Jimenez and J L Gomez-Eyles ldquoEffectsof biochar and greenwaste compost amendments on mobilitybioavailability and toxicity of inorganic and organic con-taminants in a multi-element polluted soilrdquo EnvironmentalPollution vol 158 no 6 pp 2282ndash2287 2010
[10] N Hagemann K Spokas H-P Schmidt R Kagi M Bohlerand T Bucheli ldquoActivated carbon biochar and charcoallinkages and synergies across pyrogenic carbonrsquos ABCsrdquoWater vol 10 no 2 pp 182ndash201 2018
[11] C Sreenivas S Muralidhar and M S Rao ldquoVermicompost aviable component of IPNSS in nitrogen nutrition of ridgegourdrdquo Annals of Agricultural Research vol 21 no 1pp 108ndash113 2000
[12] AOAC Protein (Crude) in Animal Feed Combustion MethodAOAC Official Method 99003 Official Methods of AnalysisAssociation of Official Analytical Chemists GaithersburgMD USA 17th edition 2003
[13] AOAC Metals and Other Elements in Plants and Pet FoodsInductively Coupled Plasma Spectroscopic Method AOACOfficial Method 96808 Official Methods of Analysis Asso-ciation of Official Analytical Chemists Gaithersburg MDUSA 17th edition 2003
[14] L Abbey S A Rao L N Hodgins and F Briet ldquoDrying andrehydration of vermicasts do not affect nutrient bioavailabilityand seedling growthrdquo American Journal of Plant Nutritionand Fertilization Technology vol 3 no 1 pp 12ndash21 2013
[15] A E Louw-Gaume I M Rao A J Gaume and E FrossardldquoA comparative study on plant growth and root plasticityresponses of two Brachiaria forage grasses grown in nutrientsolution at low and high phosphorus supplyrdquo Plant and Soilvol 328 no 1-2 pp 155ndash164 2010
[16] K Maxwell and G N Johnson ldquoChlorophyll fluorescence-apractical guiderdquo Journal of Experimental Botany vol 51no 345 pp 659ndash668 2000
[17] H Wu C Lai G Zeng et al ldquoe interactions of compostingand biochar and their implications for soil amendment andpollution remediation a reviewrdquo Critical Reviews in Bio-technology vol 37 no 6 pp 754ndash764 2016
[18] T Sizmur T Fresno G Akgul H Frost and E Moreno-Jimenez ldquoBiochar modification to enhance sorption of in-organics from waterrdquo Bioresource Technology vol 246pp 34ndash47 2017
[19] L Martınez-Suller G Provolo D Brennan et al ldquoA note onthe estimation of nutrient value of cattle slurry using easilydetermined physical and chemical parametersrdquo Irish Journalof Agricultural and Food Resarch vol 49 pp 93ndash97 2010
International Journal of Agronomy 9
b bc bc
aC
C
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
50
100
150
200
250
Plan
t hei
ght (
cm)
PH1PH2
(a)
bcb
c c
a
BCBC
B
A
C
Bioc DWB SVB VTB Pro-BXTreatments
00
20
40
60
80
100
Stem
dia
met
er (m
m)
SD1SD2
(b)
b b bc
a
C CB
A
D
Bioc DWB SVB VTB Pro-BX
Tota
l lea
f fre
sh w
eigh
t (g
plan
t)
Treatments
00
50
100
150
200
250
LFW1LFW2
(c)
bbc
cd
a
BCD
B
A
D
Bioc DWB SVB VTB Pro-BXTreatments
00
150
300
450
600
750
Mea
n le
af ar
ea (c
m2 )
LA1LA2
(d)
Figure 4 Plant height (PH) stem diameter (SD) leaf area (LA) and total edible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculatedbiochar (SVB) vermicast tea-inoculated biochar (VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical lettersrepresent mean separation by the least significant difference (α 005) at the first (1) and the second (2) harvests respectively Vertical lineson bars represent standard error of the means
c c
b b
a
BB
A A
B
Bioc DWB SVB VTB Pro-BX
Leaf
gre
enne
ss (S
PAD
val
ue)
Treatments
00
100
200
300
400
500
600
LG1LG2
(a)
a aa a
aC C
A
B
C
Bioc DWB SVB VTB Pro-BXTreatments
00
10
20
30
40
50
60
Ant
hocy
anin
cont
ent (
ACI
)
AC1AC2
(b)
Figure 3 Leaf greenness and anthocyanin content of Swiss chard (Beta vulgaris subsp vulgaris) cv Rhubarb chard as affected by biocharalone (Bioc) deionized water-inoculated biochar (DWB) solid vermicast-inoculated biochar (SVB) vermicast tea-inoculated biochar(VTB) and Promix-BX alone (Pro-BX) Lowercase and uppercase alphabetical letters represent mean separation by the least significantdifference (α 005) at the first (1) and the second (2) harvests respectively Vertical lines on bars represent standard error of the means
International Journal of Agronomy 7
surface area and fresh weight at first harvest was Pro-BXgtBiocgtDWB SVBgtVTB (Figures 4(c)ndash4(d)) istrend drastically changed at the second harvest e onlytreatment that increased total leaf area and leaf fresh weightat the second harvest was VTB ie by approximately 102-and 188-fold compared to those at the first harvest On thecontrary total leaf area was significantly (Plt 005) reducedby approximately 042-fold for SVB 074-fold for DWB069-fold for Bioc and 090-fold for Pro-BX (Figure 4(c))while leaf fresh weight was significantly reduced by ap-proximately 033-fold for DWB 028-fold for Bioc and 070-fold for Pro-BX but was not altered by SVB (Figure 4(d)) atthe second harvest as compared to the first harvest A 2-dimensional biplot principal component analysis (PCA) wasused to further explain relationships between the treatmentsand the growth components e PCA biplot explained 92of the variations in the dataset for the plant growth com-ponents as affected by the media treatments Pro-BX BiocDWB SVB and VTB (Figure 5)
ere were distinct differences in the media except thatBioc and DWB were similar and both appeared in the samequadrant on the PCA biplot e plant growth componentsat the first harvest can be found in the first quadrant with thePro-BX treatment is suggested that the PCA plot agreedwith Figures 3 and 4 that the Pro-BX treatment significantlyincreased plant growth components at the first harvest BothSVB and VTB can be found in quadrant 2 of the PCA biplotwith the plant growth components at the second harvestelocation of SVB relative to VTB and the plant growthcomponents suggested that the latter was more effective ininfluencing the plant growth components Neither Bioc norDWB influenced plant growth ese showed that the effectof treatment VTB which was not apparent in the first fourweeks became obvious Additionally VTB recorded thehighest effect on the Swiss chard plant growth componentsat the second harvest us the VTB treatment delayed therelease of nutrients but was made available eventually toincrease the Swiss chard plant growth and yield during theregrowth phase after the first harvest ese findings can beconfirmed by the results of the nutrient release experimentsin Figures 1 and 2 as shown on the PCA biplot
In conclusion the study confirmed that inoculation ofbiochar with vermicast can increase its adsorption capacityfor nutrients which will subsequently be released slowly toplants for root uptake and plant utilization It is evident fromthe present study that the nutrient release rate of inoculatedbiochar is initially slow Vermicast tea-inoculated biocharand solid vermicast-inoculated biochar have similar nutrientrelease patterns and proved to be highly activated Inocu-lated biochar characteristically releases nutrients slowly witha long-lasting impact on growing media environment andultimately plant productivity Comparatively vermicast teawas the most effective in inoculation of the biochar and assuch it was the most efficacious under the conditions of thisstudy Future investigation should consider microbial ac-tivities in these media
e nutrient release plant nutrient uptake and plant growthdata used to support the findings of this study are includedwithin the supplementary information files
Conflicts of Interest
e authors declare that they have no conflicts of interest
Acknowledgments
e authors wish to thank Dr Samuel Asiedu for his as-sistance during the experimentation and Dr NancyMacLean for her guidance on performing the statisticalanalysis However the authors wish to thank Proton PowerInc Tennessee USA for the donation of the biochar
Supplementary Materials
e supplementary files with data showed in S1ndashS11 wereused to report the outcomes of the study e commonacronyms used were as follows Bioc biochar aloneDWB deionized water-inoculated biochar SVB solidvermicast-inoculated biochar VTB vermicast tea-inocu-lated biochar Pro-BXPromix-BX soilless medium aloneS1 the data for the various growing medium salinity contentduring the nutrient release studies S2 the data for thechanges in electric conductivity of the solution when theindividual media were submerged in deionized water S3 thechanges in the acidity level (ie pH) of the solution when the
Figure 5 A two-dimensional principal component analysis biplotshowing relationships among media treatments as active variablesand plant growth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content (AC)plant height (PH) stem diameter (SD) leaf area (LA) and totaledible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc)deionized water-inoculated biochar (DWB) solid vermicast-in-oculated biochar (SVB) vermicast tea-inoculated biochar (VTB)and Promix-BX alone (Pro-BX) at the first (1) and the second (2)harvests respectively
8 International Journal of Agronomy
individual media were submerged in deionized water S4 thetotal dissolved solids in solution when the individual mediawere submerged in deionized water S5 S6 S7 and S8 theconcentrations of calcium potassium nitrate and sodiumions in solution when the individual media were submergedin the deionized water S9 the data for a two-dimensionalprincipal component analysis biplot showing relationshipsamong media treatments as active variables and plantgrowth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content(AC) plant height (PH) stem diameter (SD) leaf area (LA)and total edible leaf fresh weight (LFW) of Swiss chard (Betavulgaris subsp vulgaris) cv Rhubarb chard as affected by thegrowing medium treatments at the first (1) and the second(2) harvests respectively S10 the data for the mineralnutrient composition of the individual growing media be-fore the beginning of the nutrient release studies S11 thedata for plant growth and yield components as affected bythe individual growing medium treatments (SupplementaryMaterials)
References
[1] G Agegnehu A K Srivastava and M I Bird ldquoe role ofbiochar and biochar-compost in improving soil quality andcrop performance a reviewrdquo Applied Soil Ecology vol 119pp 156ndash170 2017
[2] R Xiao M K Awasthi R Li et al ldquoRecent developments inbiochar utilization as an additive in organic solid wastecomposting a reviewrdquo Bioresource Technology vol 246pp 203ndash213 2017
[3] Y Yuan H Chen W Yuan D Williams J T Walker andW Shi ldquoIs biochar-manure co-compost a better solution forsoil health improvement and N2O emissions mitigationrdquo SoilBiology and Biochemistry vol 113 pp 14ndash25 2017
[4] A Grewal L Abbey and L R Gunupuru ldquoProductionprospects and potential application of pyroligneous acid inagriculturerdquo Journal of Analytical and Applied Pyrolysisvol 135 pp 152ndash159 2018
[5] G Agegnehu A M Bass P N Nelson B MuirheadG Wright and M I Bird ldquoBiochar and biochar-compost assoil amendments effects on peanut yield soil properties andgreenhouse gas emissions in tropical North QueenslandAustraliardquo Agriculture Ecosystems amp Environment vol 213pp 72ndash85 2015
[6] N Khan I Clark M A Sanchez-Monedero et al ldquoPhysicaland chemical properties of biochars co-composted withbiowastes and incubated with a chicken litter compostrdquoChemosphere vol 142 pp 14ndash23 2016
[7] F Rees C Germain T Sterckeman and J-L Morel ldquoPlantgrowth and metal uptake by a non-hyperaccumulating species(Lolium perenne) and a Cd-Zn hyperaccumulator (Noccaeacaerulescens) in contaminated soils amended with biocharrdquoPlant and Soil vol 395 no 1-2 pp 57ndash73 2015
[8] J Pietikainen O Kiikkila andH Fritze ldquoCharcoal as a habitatfor microbes and its effect on the microbial community of theunderlying humusrdquo Oikos vol 89 no 2 pp 231ndash242 2000
[9] L Beesley E Moreno-Jimenez and J L Gomez-Eyles ldquoEffectsof biochar and greenwaste compost amendments on mobilitybioavailability and toxicity of inorganic and organic con-taminants in a multi-element polluted soilrdquo EnvironmentalPollution vol 158 no 6 pp 2282ndash2287 2010
[10] N Hagemann K Spokas H-P Schmidt R Kagi M Bohlerand T Bucheli ldquoActivated carbon biochar and charcoallinkages and synergies across pyrogenic carbonrsquos ABCsrdquoWater vol 10 no 2 pp 182ndash201 2018
[11] C Sreenivas S Muralidhar and M S Rao ldquoVermicompost aviable component of IPNSS in nitrogen nutrition of ridgegourdrdquo Annals of Agricultural Research vol 21 no 1pp 108ndash113 2000
[12] AOAC Protein (Crude) in Animal Feed Combustion MethodAOAC Official Method 99003 Official Methods of AnalysisAssociation of Official Analytical Chemists GaithersburgMD USA 17th edition 2003
[13] AOAC Metals and Other Elements in Plants and Pet FoodsInductively Coupled Plasma Spectroscopic Method AOACOfficial Method 96808 Official Methods of Analysis Asso-ciation of Official Analytical Chemists Gaithersburg MDUSA 17th edition 2003
[14] L Abbey S A Rao L N Hodgins and F Briet ldquoDrying andrehydration of vermicasts do not affect nutrient bioavailabilityand seedling growthrdquo American Journal of Plant Nutritionand Fertilization Technology vol 3 no 1 pp 12ndash21 2013
[15] A E Louw-Gaume I M Rao A J Gaume and E FrossardldquoA comparative study on plant growth and root plasticityresponses of two Brachiaria forage grasses grown in nutrientsolution at low and high phosphorus supplyrdquo Plant and Soilvol 328 no 1-2 pp 155ndash164 2010
[16] K Maxwell and G N Johnson ldquoChlorophyll fluorescence-apractical guiderdquo Journal of Experimental Botany vol 51no 345 pp 659ndash668 2000
[17] H Wu C Lai G Zeng et al ldquoe interactions of compostingand biochar and their implications for soil amendment andpollution remediation a reviewrdquo Critical Reviews in Bio-technology vol 37 no 6 pp 754ndash764 2016
[18] T Sizmur T Fresno G Akgul H Frost and E Moreno-Jimenez ldquoBiochar modification to enhance sorption of in-organics from waterrdquo Bioresource Technology vol 246pp 34ndash47 2017
[19] L Martınez-Suller G Provolo D Brennan et al ldquoA note onthe estimation of nutrient value of cattle slurry using easilydetermined physical and chemical parametersrdquo Irish Journalof Agricultural and Food Resarch vol 49 pp 93ndash97 2010
International Journal of Agronomy 9
surface area and fresh weight at first harvest was Pro-BXgtBiocgtDWB SVBgtVTB (Figures 4(c)ndash4(d)) istrend drastically changed at the second harvest e onlytreatment that increased total leaf area and leaf fresh weightat the second harvest was VTB ie by approximately 102-and 188-fold compared to those at the first harvest On thecontrary total leaf area was significantly (Plt 005) reducedby approximately 042-fold for SVB 074-fold for DWB069-fold for Bioc and 090-fold for Pro-BX (Figure 4(c))while leaf fresh weight was significantly reduced by ap-proximately 033-fold for DWB 028-fold for Bioc and 070-fold for Pro-BX but was not altered by SVB (Figure 4(d)) atthe second harvest as compared to the first harvest A 2-dimensional biplot principal component analysis (PCA) wasused to further explain relationships between the treatmentsand the growth components e PCA biplot explained 92of the variations in the dataset for the plant growth com-ponents as affected by the media treatments Pro-BX BiocDWB SVB and VTB (Figure 5)
ere were distinct differences in the media except thatBioc and DWB were similar and both appeared in the samequadrant on the PCA biplot e plant growth componentsat the first harvest can be found in the first quadrant with thePro-BX treatment is suggested that the PCA plot agreedwith Figures 3 and 4 that the Pro-BX treatment significantlyincreased plant growth components at the first harvest BothSVB and VTB can be found in quadrant 2 of the PCA biplotwith the plant growth components at the second harvestelocation of SVB relative to VTB and the plant growthcomponents suggested that the latter was more effective ininfluencing the plant growth components Neither Bioc norDWB influenced plant growth ese showed that the effectof treatment VTB which was not apparent in the first fourweeks became obvious Additionally VTB recorded thehighest effect on the Swiss chard plant growth componentsat the second harvest us the VTB treatment delayed therelease of nutrients but was made available eventually toincrease the Swiss chard plant growth and yield during theregrowth phase after the first harvest ese findings can beconfirmed by the results of the nutrient release experimentsin Figures 1 and 2 as shown on the PCA biplot
In conclusion the study confirmed that inoculation ofbiochar with vermicast can increase its adsorption capacityfor nutrients which will subsequently be released slowly toplants for root uptake and plant utilization It is evident fromthe present study that the nutrient release rate of inoculatedbiochar is initially slow Vermicast tea-inoculated biocharand solid vermicast-inoculated biochar have similar nutrientrelease patterns and proved to be highly activated Inocu-lated biochar characteristically releases nutrients slowly witha long-lasting impact on growing media environment andultimately plant productivity Comparatively vermicast teawas the most effective in inoculation of the biochar and assuch it was the most efficacious under the conditions of thisstudy Future investigation should consider microbial ac-tivities in these media
e nutrient release plant nutrient uptake and plant growthdata used to support the findings of this study are includedwithin the supplementary information files
Conflicts of Interest
e authors declare that they have no conflicts of interest
Acknowledgments
e authors wish to thank Dr Samuel Asiedu for his as-sistance during the experimentation and Dr NancyMacLean for her guidance on performing the statisticalanalysis However the authors wish to thank Proton PowerInc Tennessee USA for the donation of the biochar
Supplementary Materials
e supplementary files with data showed in S1ndashS11 wereused to report the outcomes of the study e commonacronyms used were as follows Bioc biochar aloneDWB deionized water-inoculated biochar SVB solidvermicast-inoculated biochar VTB vermicast tea-inocu-lated biochar Pro-BXPromix-BX soilless medium aloneS1 the data for the various growing medium salinity contentduring the nutrient release studies S2 the data for thechanges in electric conductivity of the solution when theindividual media were submerged in deionized water S3 thechanges in the acidity level (ie pH) of the solution when the
Figure 5 A two-dimensional principal component analysis biplotshowing relationships among media treatments as active variablesand plant growth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content (AC)plant height (PH) stem diameter (SD) leaf area (LA) and totaledible leaf fresh weight (LFW) of Swiss chard (Beta vulgaris subspvulgaris) cv Rhubarb chard as affected by biochar alone (Bioc)deionized water-inoculated biochar (DWB) solid vermicast-in-oculated biochar (SVB) vermicast tea-inoculated biochar (VTB)and Promix-BX alone (Pro-BX) at the first (1) and the second (2)harvests respectively
8 International Journal of Agronomy
individual media were submerged in deionized water S4 thetotal dissolved solids in solution when the individual mediawere submerged in deionized water S5 S6 S7 and S8 theconcentrations of calcium potassium nitrate and sodiumions in solution when the individual media were submergedin the deionized water S9 the data for a two-dimensionalprincipal component analysis biplot showing relationshipsamong media treatments as active variables and plantgrowth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content(AC) plant height (PH) stem diameter (SD) leaf area (LA)and total edible leaf fresh weight (LFW) of Swiss chard (Betavulgaris subsp vulgaris) cv Rhubarb chard as affected by thegrowing medium treatments at the first (1) and the second(2) harvests respectively S10 the data for the mineralnutrient composition of the individual growing media be-fore the beginning of the nutrient release studies S11 thedata for plant growth and yield components as affected bythe individual growing medium treatments (SupplementaryMaterials)
References
[1] G Agegnehu A K Srivastava and M I Bird ldquoe role ofbiochar and biochar-compost in improving soil quality andcrop performance a reviewrdquo Applied Soil Ecology vol 119pp 156ndash170 2017
[2] R Xiao M K Awasthi R Li et al ldquoRecent developments inbiochar utilization as an additive in organic solid wastecomposting a reviewrdquo Bioresource Technology vol 246pp 203ndash213 2017
[3] Y Yuan H Chen W Yuan D Williams J T Walker andW Shi ldquoIs biochar-manure co-compost a better solution forsoil health improvement and N2O emissions mitigationrdquo SoilBiology and Biochemistry vol 113 pp 14ndash25 2017
[4] A Grewal L Abbey and L R Gunupuru ldquoProductionprospects and potential application of pyroligneous acid inagriculturerdquo Journal of Analytical and Applied Pyrolysisvol 135 pp 152ndash159 2018
[5] G Agegnehu A M Bass P N Nelson B MuirheadG Wright and M I Bird ldquoBiochar and biochar-compost assoil amendments effects on peanut yield soil properties andgreenhouse gas emissions in tropical North QueenslandAustraliardquo Agriculture Ecosystems amp Environment vol 213pp 72ndash85 2015
[6] N Khan I Clark M A Sanchez-Monedero et al ldquoPhysicaland chemical properties of biochars co-composted withbiowastes and incubated with a chicken litter compostrdquoChemosphere vol 142 pp 14ndash23 2016
[7] F Rees C Germain T Sterckeman and J-L Morel ldquoPlantgrowth and metal uptake by a non-hyperaccumulating species(Lolium perenne) and a Cd-Zn hyperaccumulator (Noccaeacaerulescens) in contaminated soils amended with biocharrdquoPlant and Soil vol 395 no 1-2 pp 57ndash73 2015
[8] J Pietikainen O Kiikkila andH Fritze ldquoCharcoal as a habitatfor microbes and its effect on the microbial community of theunderlying humusrdquo Oikos vol 89 no 2 pp 231ndash242 2000
[9] L Beesley E Moreno-Jimenez and J L Gomez-Eyles ldquoEffectsof biochar and greenwaste compost amendments on mobilitybioavailability and toxicity of inorganic and organic con-taminants in a multi-element polluted soilrdquo EnvironmentalPollution vol 158 no 6 pp 2282ndash2287 2010
[10] N Hagemann K Spokas H-P Schmidt R Kagi M Bohlerand T Bucheli ldquoActivated carbon biochar and charcoallinkages and synergies across pyrogenic carbonrsquos ABCsrdquoWater vol 10 no 2 pp 182ndash201 2018
[11] C Sreenivas S Muralidhar and M S Rao ldquoVermicompost aviable component of IPNSS in nitrogen nutrition of ridgegourdrdquo Annals of Agricultural Research vol 21 no 1pp 108ndash113 2000
[12] AOAC Protein (Crude) in Animal Feed Combustion MethodAOAC Official Method 99003 Official Methods of AnalysisAssociation of Official Analytical Chemists GaithersburgMD USA 17th edition 2003
[13] AOAC Metals and Other Elements in Plants and Pet FoodsInductively Coupled Plasma Spectroscopic Method AOACOfficial Method 96808 Official Methods of Analysis Asso-ciation of Official Analytical Chemists Gaithersburg MDUSA 17th edition 2003
[14] L Abbey S A Rao L N Hodgins and F Briet ldquoDrying andrehydration of vermicasts do not affect nutrient bioavailabilityand seedling growthrdquo American Journal of Plant Nutritionand Fertilization Technology vol 3 no 1 pp 12ndash21 2013
[15] A E Louw-Gaume I M Rao A J Gaume and E FrossardldquoA comparative study on plant growth and root plasticityresponses of two Brachiaria forage grasses grown in nutrientsolution at low and high phosphorus supplyrdquo Plant and Soilvol 328 no 1-2 pp 155ndash164 2010
[16] K Maxwell and G N Johnson ldquoChlorophyll fluorescence-apractical guiderdquo Journal of Experimental Botany vol 51no 345 pp 659ndash668 2000
[17] H Wu C Lai G Zeng et al ldquoe interactions of compostingand biochar and their implications for soil amendment andpollution remediation a reviewrdquo Critical Reviews in Bio-technology vol 37 no 6 pp 754ndash764 2016
[18] T Sizmur T Fresno G Akgul H Frost and E Moreno-Jimenez ldquoBiochar modification to enhance sorption of in-organics from waterrdquo Bioresource Technology vol 246pp 34ndash47 2017
[19] L Martınez-Suller G Provolo D Brennan et al ldquoA note onthe estimation of nutrient value of cattle slurry using easilydetermined physical and chemical parametersrdquo Irish Journalof Agricultural and Food Resarch vol 49 pp 93ndash97 2010
International Journal of Agronomy 9
individual media were submerged in deionized water S4 thetotal dissolved solids in solution when the individual mediawere submerged in deionized water S5 S6 S7 and S8 theconcentrations of calcium potassium nitrate and sodiumions in solution when the individual media were submergedin the deionized water S9 the data for a two-dimensionalprincipal component analysis biplot showing relationshipsamong media treatments as active variables and plantgrowth components as active observations Plant growthcomponents were leaf greenness (LG) anthocyanin content(AC) plant height (PH) stem diameter (SD) leaf area (LA)and total edible leaf fresh weight (LFW) of Swiss chard (Betavulgaris subsp vulgaris) cv Rhubarb chard as affected by thegrowing medium treatments at the first (1) and the second(2) harvests respectively S10 the data for the mineralnutrient composition of the individual growing media be-fore the beginning of the nutrient release studies S11 thedata for plant growth and yield components as affected bythe individual growing medium treatments (SupplementaryMaterials)
References
[1] G Agegnehu A K Srivastava and M I Bird ldquoe role ofbiochar and biochar-compost in improving soil quality andcrop performance a reviewrdquo Applied Soil Ecology vol 119pp 156ndash170 2017
[2] R Xiao M K Awasthi R Li et al ldquoRecent developments inbiochar utilization as an additive in organic solid wastecomposting a reviewrdquo Bioresource Technology vol 246pp 203ndash213 2017
[3] Y Yuan H Chen W Yuan D Williams J T Walker andW Shi ldquoIs biochar-manure co-compost a better solution forsoil health improvement and N2O emissions mitigationrdquo SoilBiology and Biochemistry vol 113 pp 14ndash25 2017
[4] A Grewal L Abbey and L R Gunupuru ldquoProductionprospects and potential application of pyroligneous acid inagriculturerdquo Journal of Analytical and Applied Pyrolysisvol 135 pp 152ndash159 2018
[5] G Agegnehu A M Bass P N Nelson B MuirheadG Wright and M I Bird ldquoBiochar and biochar-compost assoil amendments effects on peanut yield soil properties andgreenhouse gas emissions in tropical North QueenslandAustraliardquo Agriculture Ecosystems amp Environment vol 213pp 72ndash85 2015
[6] N Khan I Clark M A Sanchez-Monedero et al ldquoPhysicaland chemical properties of biochars co-composted withbiowastes and incubated with a chicken litter compostrdquoChemosphere vol 142 pp 14ndash23 2016
[7] F Rees C Germain T Sterckeman and J-L Morel ldquoPlantgrowth and metal uptake by a non-hyperaccumulating species(Lolium perenne) and a Cd-Zn hyperaccumulator (Noccaeacaerulescens) in contaminated soils amended with biocharrdquoPlant and Soil vol 395 no 1-2 pp 57ndash73 2015
[8] J Pietikainen O Kiikkila andH Fritze ldquoCharcoal as a habitatfor microbes and its effect on the microbial community of theunderlying humusrdquo Oikos vol 89 no 2 pp 231ndash242 2000
[9] L Beesley E Moreno-Jimenez and J L Gomez-Eyles ldquoEffectsof biochar and greenwaste compost amendments on mobilitybioavailability and toxicity of inorganic and organic con-taminants in a multi-element polluted soilrdquo EnvironmentalPollution vol 158 no 6 pp 2282ndash2287 2010
[10] N Hagemann K Spokas H-P Schmidt R Kagi M Bohlerand T Bucheli ldquoActivated carbon biochar and charcoallinkages and synergies across pyrogenic carbonrsquos ABCsrdquoWater vol 10 no 2 pp 182ndash201 2018
[11] C Sreenivas S Muralidhar and M S Rao ldquoVermicompost aviable component of IPNSS in nitrogen nutrition of ridgegourdrdquo Annals of Agricultural Research vol 21 no 1pp 108ndash113 2000
[12] AOAC Protein (Crude) in Animal Feed Combustion MethodAOAC Official Method 99003 Official Methods of AnalysisAssociation of Official Analytical Chemists GaithersburgMD USA 17th edition 2003
[13] AOAC Metals and Other Elements in Plants and Pet FoodsInductively Coupled Plasma Spectroscopic Method AOACOfficial Method 96808 Official Methods of Analysis Asso-ciation of Official Analytical Chemists Gaithersburg MDUSA 17th edition 2003
[14] L Abbey S A Rao L N Hodgins and F Briet ldquoDrying andrehydration of vermicasts do not affect nutrient bioavailabilityand seedling growthrdquo American Journal of Plant Nutritionand Fertilization Technology vol 3 no 1 pp 12ndash21 2013
[15] A E Louw-Gaume I M Rao A J Gaume and E FrossardldquoA comparative study on plant growth and root plasticityresponses of two Brachiaria forage grasses grown in nutrientsolution at low and high phosphorus supplyrdquo Plant and Soilvol 328 no 1-2 pp 155ndash164 2010
[16] K Maxwell and G N Johnson ldquoChlorophyll fluorescence-apractical guiderdquo Journal of Experimental Botany vol 51no 345 pp 659ndash668 2000
[17] H Wu C Lai G Zeng et al ldquoe interactions of compostingand biochar and their implications for soil amendment andpollution remediation a reviewrdquo Critical Reviews in Bio-technology vol 37 no 6 pp 754ndash764 2016
[18] T Sizmur T Fresno G Akgul H Frost and E Moreno-Jimenez ldquoBiochar modification to enhance sorption of in-organics from waterrdquo Bioresource Technology vol 246pp 34ndash47 2017
[19] L Martınez-Suller G Provolo D Brennan et al ldquoA note onthe estimation of nutrient value of cattle slurry using easilydetermined physical and chemical parametersrdquo Irish Journalof Agricultural and Food Resarch vol 49 pp 93ndash97 2010
![Organic Swiss chard-corrected - icia.es · 3 46 analysis showed that organic chard retained turgidity, color and brightness longer than 47 conventional chard [3,9]. Moreover, the](https://static.documents.pub/doc/80x56/5bf5581709d3f2941d8b86ca/organic-swiss-chard-corrected-iciaes-3-46-analysis-showed-that-organic-chard.jpg)
