Research Article Nitrate Sorption in an Agricultural Soil...

Hindawi Publishing CorporationApplied and Environmental Soil ScienceVolume 2013 Article ID 597824 7 pageshttpdxdoiorg1011552013597824

Research ArticleNitrate Sorption in an Agricultural Soil Profile

Wissem Hamdi1 Faten Gamaoun2 David E Pelster3 and Mongi Seffen4

1 High Institute of Agronomy Sousse University Chott Meriem 4042 Sousse Tunisia2 Applied Chemistry and Environment Research Unit EPAM 4000 Sousse Tunisia3 International Livestock Research Institute PO Box 30709 Nairobi Kenya4 Laboratory of Energy and Materials (LABEM) High School of Sciences and Technology Sousse University4011 Hammam Sousse Tunisia

Correspondence should be addressed to Wissem Hamdi wissemhemdiyahoofr

Received 6 March 2013 Revised 9 June 2013 Accepted 25 June 2013

Academic Editor Marco Trevisan

Copyright copy 2013 Wissem Hamdi et alThis 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

Increasing concentrations of NO3

minus in surface water and groundwater can cause ecological and public health effects and has comeunder increased scrutiny by both environmental scientists and regulatory agencies Formany regions though including the Sahel ofTunisia little is known about the NO

3

minus sorption capacity of soils In this project we measured NO3

minus sorption by a profile of an iso-humic soil fromChottMeriem Tunisia Soil samples were collected from four soil depths (0ndash25 25ndash60 60ndash90 and 90ndash120 cm) on 1June 2011 and their sorption capacity was determined using batch experiments under laboratory conditions The effects of contacttime the initial concentration and the soil-solution ratio on NO

3

minus sorption were investigated In general the results suggestedthat NO

3

minus was weakly retained by the Chott Meriem soil profile The quantity of NO3

minus sorption increased with depth contacttime initial concentration and soil-solution ratios To evaluate the sorption capacities of the soil samples at concentrations rangingbetween 25 and 150mg Lminus1 experimental data were fitted to both Freundlich and Langmuir isotherm sorption models The resultsindicated that Freundlich model was better for describing NO

3

minus sorption in this soil profile

1 Introduction

Nitrogen (N) is a critical nutrient needed by all plants forgrowth [1] Input of inorganic N as a fertilizer is consideredessential in modern agriculture in order to satisfy the dietaryneeds of a growing world population Nitrate (NO

3

minus) is theone of the principal N forms taken up by plants As suchinorganic N is widely used in agriculture and numerousstudies have suggested that leaching of NO

3

minus following highinput rates of chemical fertilizer and due to mineralizationof organic N already present in the soils can cause degra-dation of surface and groundwater quality Excess NO

3

minus

contaminated water supplies have been linked to outbreaksof infectious disease [2] Also NO

3

minus can be converted tonitrite in the digestive tracts of infants and ruminant animalswhich then combines with blood hemoglobin reducing itsability to carry oxygen occasionally leading to death Theability of soil to adsorb anions can reduce NO

3

minus leachingto the deeper horizons and maximize the NO

3

minus availablefor plant nutrition and can thus play a fundamental role in

enhancing soil nutrition in regions such as Mediterraneanareas where NO

3

minus availability is often a limiting factor [3]Previous studies have reported the sorption of NO

3

minus by soils[4 5] However NO

3

minus mobility in soils is mainly controlledby a number of soil properties including iron and aluminumoxide concentrations [6] organic matter content [7] pH ofsoil solutions [8] and soil texture and clay mineralogy [9]Other studies suggested that sorption ofNO

3

minus was influencedby the competitionwith other anions as Clminus [10] Qafoku et al[11] reported that NO

3

minus sorptionwas directly related toNO3

minus

concentration in the soil solutionThe NO

3

minus sorption process has been studied in manydifferent soil orders in tropical latitudes [12] includingOxisols [13] as well as in ultisols of the southeastern andmid-Atlantic United States [14] and in forest soils of the Americannorthwest [15] However none of these investigated NO

3

minus

dynamics for the soils of Tunisia in particular the soils ofthe Sousse region which is considered to be one of the mostimportant crop production areas in Tunisia The aim of this

2 Applied and Environmental Soil Science

Table 1 Physiochemical properties of iso-humic soil from Chott Mariam

Depths0ndash25 cm 25ndash60 cm 60ndash90 cm 90ndash120 cm

pH 812 841 856 854CEC (meq100 g of soil) 1972 2204 2345 2345OM () 07 09 11 13Total C (mg kgminus1) 10988 8255 20988 27093Total N (mg kgminus1) 900 540 510 260N-NO3 (mg kgminus1) 8647 3615 16925 3821N-NH4 (mg kgminus1) 668 329 357 339Exchangeable P (mg kgminus1) 9368 209 412 499Exchangeable Na (mg kgminus1) 575 2323 5336 1242Exchangeable Al (mg kgminus1) 7668 8723 7279 5155Exchangeable Ca (mg kgminus1) 545038 550861 587456 1730604Exchangeable K (mg kgminus1) 49123 29977 13549 10661Exchangeable Mg (mg kgminus1) 41016 43323 35683 46168Exchangeable Mn (mg kgminus1) 5916 5254 2295 422Exchangeable Fe (mg kgminus1) 3357 2462 901 338Clay () 128 244 305 258Silt () 38 152 10 152Sand () 492 604 595 591Texture Sandy loam Sandy loam Clay Clay loam

study was to investigate the NO3

minus sorption capacity of thesesoils by soil depth

2 Materials and Methods

21 Site Description Soil samples were collected from a citrusorchard at the High Agronomic Institute of Chott MeriemSousse (35∘541015840N10∘361015840E) on 1 June 2011The climate is Medi-terranean and is characterized by hot dry summers andmod-erate wet winters an average annual precipitation of 230mmand a mean annual temperature of 185∘C Ammoniumnitrate fertilizer is applied annually at a rate of 200 kgNhaminus1The soils are medium-textured brown iso-humic [16] with anaverage infiltration rate of 45mmhminus1

22 Chemical Analysis Four soil pits were sampled to a depthof 120 cm and separated into four depths 0ndash25 25ndash60 60ndash90and 90ndash120 cm Samples were air-dried and ground to pass a2mm sieve Soil pH was determined in 1 2 soil water sus-pension [17] organicmatter (OM)determined by thewet oxi-dationmethod (Walkley andBlack) particle-size distributionby the pipette method [18] cation exchange capacity (CEC)by the BaCl

2extraction method [19] Mehlich-III [20] P Ca

Mg Fe Al Cd Cu andMnwere determined by equilibrating25 g of air-dried soil sample with 25mL of Mehlich-IIIextracting solution for 5min and filtering throughWhatmanno 40 filter paperThe different concentrations in the extractswere measured using an inductively coupled plasma opticalemission spectrometer (Perkins Elmer Model 4300DV) SoilN-NO

3

minus and N-NH4

+ concentrations were analysed usingthe steam distillation method [21]

23 Batch Study The NO3

minus sorption on the iso-humic soilof Chott Meriem was studied as a function of the soil tosoil-solution NO

3

minus ratio Nitrate sorption in each horizonwas determined via batch equilibration techniques adaptedfrom [14] The following soil solution ratios (1 125 25and 50) have been proposed in the literature [22] andwere used in this study The concentration of the solutionwas 100mg NO

3

minus Lminus1 The temperature was 20∘C Briefly 5 gof air-dried soil from each soil subsample was equilibratedwith 100mL of NO

3

minus solution Two drops of toluene wereadded to each mixture to prevent any biological NO

3

minus trans-formations Equilibration was estimated to have occurredafter the mixture was shaken on a reciprocal shaker at 20∘Cfor 1 h at a rate of 100 oscillationsmin After equilibrationthe mixtures were centrifuged at 5000 rpm for 10min andthe NO

3

minus concentration of the supernatant was determinedimmediately using a spectrophotometer at 220 nm

The amount of adsorption at equilibrium119876119890(mg gminus1) was

calculated by

119876119890= (119862119894minus 119862119890

119872) times 119881 (1)

where119862119894and119862

119890(mg Lminus1) are the liquid-phase concentrations

of NO3

minus at initial conditions and at equilibrium respectively119881 is the volume of the solution (L) 119872 is the mass of dryadsorbent used (g)

3 Results and Discussion

31 Soil Properties Themain soil properties thought to influ-ence NO

3

minus sorption and movement are provided in Table 1

Applied and Environmental Soil Science 3

The pH for these soil horizons were all above 8 while soiltexture varied between fine sandy loam and sandy clay loamin the two first horizons (0ndash25 cm) and (25ndash60 cm) andclay and sandy clay loam for the two next deeper horizons(60ndash90 cm and 90ndash120 cm) respectively The variation intexture reflected the differences in parent materials [23] Claycontent which tended to increase with depth can affect soilfertility and water and nutrient holding capacities as wellas plant root movement [24] The organic matter contentfor the different soils horizons showed a similar pattern tothe clay where the concentrations tended to increase in thedeeper horizons (Table 1) It has been reported that NO

3

minus

mobility is often related to the organic matter content andcould be due to the higher cation exchange capacity [25]The amount of exchangeable cations differed markedly Ca2+concentrationswere high in the different horizons and tendedto increase at depth The inverse can be seen for otherexchangeable cations such K+ and Fe2+ where concentrationswere moderate and decreased with increasing depth For theother ions there were no distinct patterns in terms of theamount and distribution within the different horizons of thesoil profile

32 Effect of Contact Time on NO3minus Sorption As shown in

Figure 1 the NO3

minus adsorption rate was rapid for the first60min and decreased over time Equilibrium sorption wasestablished after approximately 120min for NO

3

minus ions at aninitial concentration of 100mg Lminus1 From the results it can beseen that the contact time required for maximum sorptionof NO

3

minus by different soil profile was dependent on theinitial NO

3

minus concentration and on certain soil componentsespecially the OM and clay content This behavior suggeststhat at the initial stage sorption takes place rapidly on theexternal surface of the adsorbent followed by a slower internaldiffusion process which may be the rate-determining stepThis trend in NO

3

minus sorption suggests that the binding maybe through interactionswith functional groups located on thesurface of the soil According to these results the contact timewas fixed at 120min for the batch experiments to make surethat equilibrium was attained The results demonstrated thatat a fixed adsorbent dosage the NO

3

minus sorption was higher indeeper horizons than in superficial horizonsThe two deepesthorizons contained more organic matter which counterbal-ances the effect of positive charges of the oxides on NO

3

minus

sorption Indeed organic groups displace water ligands at thepositively charged sites on surfaces oxides [26] As shown inTable 1 the amount of clay increased with depth along withincreasingCECwhich enhances theNO

3

minus sorption capacity

33 Effect of Soil-Solution Ratios onNO3minus Sorption The sorp-

tion of NO3

minus on iso-humic soil of Chott Meriem was studiedas a function of the soil to soil-solution NO

3

minus ratio Thefollowing soil solution ratios (1 125 25 and 50) havebeen proposed in the literature [22] and used in this studyThe experimentwas conducted in batchAs shown in Figure 2there was not a lot of variation between the different depthsin the NO

3

minus adsorption capacity at a low soil solution ratio(1) However the NO

3

minus sorption capacity increased with anincrease in the soil solution ratio When the ratio increased

0

0005

001

0015

002

0025

003

0035

004

0045

005

0 20 40 60 80 100 120 140Contact time (min)

0ndash25 cm25ndash60 cm


Sorp

tion

NO

3minus

(mg k

gminus1)

Figure 1 Effect of contact time on NO3

minus sorption for 4 soildepths from a batch experiment using an iso-humic soil from ChottMeriam Tunisia (Initial conditions for the batch experiment were100mg NO

3

minus Lminus1 22∘C and 5 g air-dried soil)

0

001

002

003

004

005

006

0 10 20 30 40 50 60 Ratio (masssolution) ()



Sorp

tion

NO

3minus

(mg k

gminus1)

Figure 2 Effect of soil-solution ratios on NO3

minus sorption for 4 soildepths from a batch experiment using an iso-humic soil from ChottMeriam Tunisia (soilsolution ratios 1 125 25 and 5022∘C 24 h)


0

001

002

003

004

005

006

007

0 50 100 150 200



Sorp

tion

NO

3minus

(mg k

gminus1)

Concentration NO3minus (mg Lminus1)

Figure 3 Effect of initial NO3

minus concentration onNO3

minus sorption for 4 soil depths from a batch experiment using an iso-humic soil fromChottMeriam Tunisia (25 50 75 100 125 and 150mg Lminus1 22∘C 24 h and soil mass = 5 g)

Table 2 Langmuir and Freundlich parameters for sorption of NO3

minus on four depths of iso-humic soil from Chott Mariam Tunisia


Langmuir parameters119876 (mgg) 0153 0134 0144 0121119870119871(Lmg) 00031 00041 00046 000681198772 089 095 093 097

Freundlich parameters119870119865

000086 0001 00012 0002119899 123 127 128 1441198772 099 099 098 099

from 1 to 50 the NO3

minus sorption capacities increasedfrom 00012 to 0048 00015 to 0051 00016 to 00525 and00018 to 0054 for the 0ndash25 25ndash60 60ndash90 and 90ndash120 cmdepths respectively These observations infer that increasingsoil solution ratios play a major role in the increasing NO

3

minus

sorption capacity by the soils similar to results obtained byQafoku et al [11] It can be noted that the ratio increases asthemass of soil increases It has been suggested that increasedsoil mass causes increased variable charges in the solutionand consequently increased sorption of NO

3

minus Furthermoreit was reported that NO

3

minus mobility was often related tothe active components of organic matter and the clay-sizedfractions [27] likely due to the resulting increase inCEC [25]

34 Effect of Initial NO3minus Concentration on NO3

minus SorptionSeeing that the initial NO

3

minus concentration in solution pro-vides an important driving force to overcome mass transferlimitations of NO

3

minus between aqueous and solid phases ahigher initial NO

3

minus concentration will increase the sorp-tion process The effect of initial NO

3


minus sorption for all soil depths was investigated in the

following concentrations (25 50 75 100 125 and 150mgNO3

minus Lminus1) Figure 3 shows the change of the equilibriumsorption capacity of soil samples with different initial NO

3

minus

concentrations It was observed that the amount of sorbedNO3

minus at equilibrium increased with increasing initial NO3

minus

concentration for all soil horizons although rates differedaccording to the soil layer

Many previous works reported that at low concentrationmore NO

3

minus is sorbed by the soil than is left in solutionThereis some controversy concerning the mechanism of NO

3

minus

adsorption at low concentration in soil Toner et al [28]proposed a totally reversible adsorption which is a simpleelectrostatic retention (ie the adsorption is the result ofvan der Waals type interactions) On the contrary Qafokuet al [11] explained the adsorption as an overlapping orinterpenetration of double layers around positively chargedAl-polymers and negatively charged silicate minerals

Below concentrations of 100mg NO3

minus Lminus1 NO3

minus sorp-tion was low in the top horizon (0ndash25 cm) higher in the 25ndash60 cm horizon and peaked within the 60ndash90 cm and 90ndash120 cm depths Above concentrations of 125 NO

3

minusmgLminus1


minus5

minus45

minus4

minus35

minus3

minus25

minus23 35 4 45 5 55



ln Ce

ln Q

a

Figure 4 Langmuir isotherms for NO3

minus sorption by soil profile at (25 50 75 100 125 and 150mg NO3

minus Lminus1 22∘C 24 h and soil mass = 5 g)

1000

1500

2000

2500

3000

3500

0 50 100 150 200Qe (mgL)

QaQ

e(g

Lminus1)



Figure 5 Freundlich isotherms for NO3


minus Lminus1 22∘C 24 h and soil mass =5 g)


the slope of the curves decreased This decline in NO3

minus

sorption with increased initial concentrations in all soildepths is likely due to the weakening of attractive forcesbetween NO

3

minus and the soil matrix as well as desorption ofother anions (eg P) as suggested by Strahm and Harrison[15]

35 Adsorption Equilibrium and Isotherms To facilitate theestimation of the NO

3

minus sorption capacities of the soilsat the following concentrations (25 50 75 100 125 and150mg NO

3

minus Lminus1) the experimental data were fitted to theFreundlich and Langmuir equilibrium adsorption isothermmodels The Langmuir equation is as follows 119862

119890119876119890=

1119876119898119887 + 119862

119890119876119898 where 119862

119890is the equilibrium concentration

of NO3

minus in the solution (mgL) 119876119890the amount of NO

3

minus

sorbed per unit weight of soil (mg kgminus1) and119876119898and 119887 are the

Langmiur constants signifying the sorption capacity of theadsorbent and energy of the sorption process respectivelyThe sorption data was plotted (Figure 4) and 119876

119898and 119870

119871

(listed in Table 2) were calculated from the intercept and theslope of the plots

The Langmuir equation characterized the NO3

minus sorptiondata fairly well with 1198772 values between 089 and 097 forthe different soil horizons (Table 2) The adjusted 1198772 valuessuggest that the Langmuir isotherm provides a good modelof the sorption system only for the 25ndash60 cm and 90ndash120 cmhorizons In this work it appears that the 119876

119898was greatest

in the surface horizon and tended to decrease with depthHowever 119870

119871increased with depth which suggests that not

all inorganic sites may be available for NO3

minus binding [15]The Freundlich equation is as follows ln(119902

119890) = ln(119870

119865) +

(1119899) ln(119862119890) where 119902

119890is the amount of NO

3

minus per gram of soilat the equilibrium 119862 is the NO

3

minus concentration in solutionat the equilibrium and 119870 and 119899 are the empirical constantsindicating the adsorption capacity and adsorption intensityrespectively Figure 5 shows the plot of ln(119902

119890) versus ln(119862

119890)

enabling the constants 119870 and 119899 to be determined from theintercept and slope respectively (Table 2) The 1198772 valuesfor the Freundlich isotherm model were greater than thosefrom the Langmuir model (Table 2) The values of 119899 for allsoil samples were found to be nearly similar at all depthsindicating reasonable sorption of NO

3

minus onto soil samplesat the concentration studied as is evident from Table 2Additionally it can be also shown that the values of (119870

119865)

which is a measure of the degree of sorption decrease atgreater depths consistent with previous studies [15]

4 Conclusion

In this study the sorption of NO3

minus from aqueous solutionsonto alkaline soils of the ChottMeriem region was examinedThe results indicated that the soil NO

3

minus sorption capacity ofdifferent horizons was affected by the ratio of the soil massand solution volume the initial NO

3

minus concentration and thecontact time The amount of NO

3

minus sorbed on soils increasedwith depth However a considerable amount of NO

3

minus in thesoil was not sorbed by the soil and thus it is expected that

the majority of NO3

minus in excess of biological immobilizationrates will be transported through the soils into ground orsurface waters Also although both Langmuir and Freundlichisothermmodels were used to describe the sorption behaviorof NO

3

minus on soil samples the Freundlich adsorption isothermmodel better described the NO

3


References

[1] N M Crawford and A D M Glass ldquoMolecular and physiolog-ical aspects of nitrate uptake in plantsrdquo Trends in Plant Sciencevol 3 no 10 pp 389ndash395 1998

[2] L Fewtrell ldquoDrinking-water nitrate methemoglobinemia andglobal burden of disease a discussionrdquo Environmental HealthPerspectives vol 112 no 14 pp 1371ndash1374 2004

[3] F A Rutigliano S Castaldi R DrsquoAscoli et al ldquoSoil activitiesrelated to nitrogen cycle under three plant cover types inMediterranean environmentrdquo Applied Soil Ecology vol 43 no1 pp 40ndash46 2009

[4] J S Reynolds-Vargas D D Richter and E Bornemisza ldquoEnvi-ronmental impacts of nitrification and nitrate adsorption infertilized andisols in the Valle Central of Costa Ricardquo SoilScience vol 157 no 5 pp 289ndash299 1994

[5] M Tani T Okuten M Koike K Kuramochi and R KondoldquoNitrate adsorption in some andisols developed under differentmoisture conditionsrdquo Soil Science and Plant Nutrition vol 50no 3 pp 439ndash446 2004

[6] M T F Wong and K Wittwer ldquoPositive charge discoveredacross Western Australian wheatbelt soils challenges key soiland nitrogen management assumptionsrdquo Australian Journal ofSoil Research vol 47 no 1 pp 127ndash135 2009

[7] M R Panuccio A Muscolo and S Nardi ldquoEffect of humicsubstances on nitrogen uptake and assimilation in two speciesof pinusrdquo Journal of Plant Nutrition vol 24 no 4-5 pp 693ndash704 2001

[8] M J Donn and N W Menzies ldquoSimulated rainwater effectson anion exchange capacity and nitrate retention in FerrosolsrdquoAustralian Journal of Soil Research vol 43 no 1 pp 33ndash42 2005

[9] N Martınez-Villegas L M Flores-Velez and O DomınguezldquoSorption of lead in soil as a function of pH a study case inMexicordquo Chemosphere vol 57 no 10 pp 1537ndash1542 2004

[10] F Feder and A Findeling ldquoRetention and leaching of nitrateand chloride in an andic soil after pig manure amendmentrdquoEuropean Journal of Soil Science vol 58 no 2 pp 393ndash404 2007

[11] N P Qafoku M E Sumner and D E Radcliffe ldquoAnion trans-port in columns of variable charge subsoils nitrate and chlo-riderdquo Journal of Environmental Quality vol 29 no 2 pp 484ndash493 2000

[12] T Kinjo and P F Pratt ldquoNitrate adsorption I some acid soilsof Mexico and South Americardquo Soil Science Society of AmericaProceedings vol 35 pp 722ndash725 1971

[13] J F Dynia ldquoNitrate retention and leaching in variable chargesoils of a watershed in Sao Paulo state Brazilrdquo Communicationsin Soil Science and Plant Analysis vol 31 no 5-6 pp 777ndash7912000

[14] M J Eick W D Brady and C K Lynch ldquoCharge propertiesand nitrate adsorption of some acid Southeastern soilsrdquo Journalof Environmental Quality vol 28 no 1 pp 138ndash144 1999


[15] B D Strahm and R B Harrison ldquoNitrate sorption in a variable-charge forest soil of the Pacific Northwestrdquo Soil Science vol 171no 4 pp 313ndash321 2006

[16] FAO ldquoSoil map of worldrdquo FAO Word Soil Report 60 FAORome Italy 1989

[17] T PHignett ldquoFertilizermanualrdquoDevelopments in Plant and SoilScience vol 315 pp 163ndash186 1985

[18] G W Gee and J W Bauder Particle Size Analysis 1986[19] WHHendershot H Lalande andMDuquette ldquoIon exchange

and exchangeable cationsrdquo in Soil Sampling and Methods ofAnalysis R C Martin Ed pp 183ndash205 Canadian Society ofSoil Science Lewis Publishers Boca Raton Fla USA 1993

[20] A Mehlich ldquoMehlich 3 soil test extractant a modification ofMehlich 2 extractantrdquo Communications in Soil Science amp PlantAnalysis vol 15 no 12 pp 1409ndash1416 1984

[21] J M Bremmer and D R Keeney ldquoDetermination and isotopicratio analysis of different forms of nitrogen in soils I Apparatusand procedure for distillation for and determination of ammo-niumrdquo Soil Science Society of America Proceedings vol 29 pp504ndash507 1965

[22] K W Roy W F Moore and T S Abney ldquoDiagnosis of suddendeath syndrome of soybeanrdquo Plant Diagnostics Quarterly vol12 pp 166ndash168 1991

[23] M I S Ezenwa ldquoSome physico-chemical characteristics of soilsof basement complex and adjoining basaltic rocks of NorthernNgeriardquo in Proceedings of the 15th Annual Conference of SoilScience Society of Nigeria O Babalola Ed pp 205ndash214 1987

[24] I E Esu ldquoFertility status and management of some uplandbasement complex soils in th Nigerian tropical savanna regionrdquoNigerian Journal of Soil Science vol 7 pp 155ndash184 1987

[25] S Shoji M Nanzyo and R A Dahlgren ldquoChemical charac-teristics of volcanic ash soilsrdquo in Volcanic Ash Soils GenesisProperties and Utilization vol 153 pp 166ndash167 1993

[26] E Marcano-Martinez andM B McBride ldquoCalcium and sulfateretention by two oxisols of the Brazilian Cerradordquo Soil ScienceSociety of America Journal vol 53 no 1 pp 63ndash69 1989

[27] S M Ndala M C Scholes and M V Fey ldquoSoil propertiesand processes driving the leaching of nitrate in the forestedcatchments of the eastern escarpment of South Africardquo ForestEcology and Management vol 236 no 2-3 pp 142ndash152 2006

[28] C V Toner D L Sparks and T H Carski ldquoAnion exchangechemistry ofMiddle Atlantic soils charge properties and nitrateretention kineticsrdquo Soil Science Society of America Journal vol53 no 4 pp 1061ndash1067 1989

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Table 1 Physiochemical properties of iso-humic soil from Chott Mariam


pH 812 841 856 854CEC (meq100 g of soil) 1972 2204 2345 2345OM () 07 09 11 13Total C (mg kgminus1) 10988 8255 20988 27093Total N (mg kgminus1) 900 540 510 260N-NO3 (mg kgminus1) 8647 3615 16925 3821N-NH4 (mg kgminus1) 668 329 357 339Exchangeable P (mg kgminus1) 9368 209 412 499Exchangeable Na (mg kgminus1) 575 2323 5336 1242Exchangeable Al (mg kgminus1) 7668 8723 7279 5155Exchangeable Ca (mg kgminus1) 545038 550861 587456 1730604Exchangeable K (mg kgminus1) 49123 29977 13549 10661Exchangeable Mg (mg kgminus1) 41016 43323 35683 46168Exchangeable Mn (mg kgminus1) 5916 5254 2295 422Exchangeable Fe (mg kgminus1) 3357 2462 901 338Clay () 128 244 305 258Silt () 38 152 10 152Sand () 492 604 595 591Texture Sandy loam Sandy loam Clay Clay loam

study was to investigate the NO3

minus sorption capacity of thesesoils by soil depth

2 Materials and Methods

21 Site Description Soil samples were collected from a citrusorchard at the High Agronomic Institute of Chott MeriemSousse (35∘541015840N10∘361015840E) on 1 June 2011The climate is Medi-terranean and is characterized by hot dry summers andmod-erate wet winters an average annual precipitation of 230mmand a mean annual temperature of 185∘C Ammoniumnitrate fertilizer is applied annually at a rate of 200 kgNhaminus1The soils are medium-textured brown iso-humic [16] with anaverage infiltration rate of 45mmhminus1

22 Chemical Analysis Four soil pits were sampled to a depthof 120 cm and separated into four depths 0ndash25 25ndash60 60ndash90and 90ndash120 cm Samples were air-dried and ground to pass a2mm sieve Soil pH was determined in 1 2 soil water sus-pension [17] organicmatter (OM)determined by thewet oxi-dationmethod (Walkley andBlack) particle-size distributionby the pipette method [18] cation exchange capacity (CEC)by the BaCl

2extraction method [19] Mehlich-III [20] P Ca

Mg Fe Al Cd Cu andMnwere determined by equilibrating25 g of air-dried soil sample with 25mL of Mehlich-IIIextracting solution for 5min and filtering throughWhatmanno 40 filter paperThe different concentrations in the extractswere measured using an inductively coupled plasma opticalemission spectrometer (Perkins Elmer Model 4300DV) SoilN-NO

3

minus and N-NH4

+ concentrations were analysed usingthe steam distillation method [21]

23 Batch Study The NO3

minus sorption on the iso-humic soilof Chott Meriem was studied as a function of the soil tosoil-solution NO

3

minus ratio Nitrate sorption in each horizonwas determined via batch equilibration techniques adaptedfrom [14] The following soil solution ratios (1 125 25and 50) have been proposed in the literature [22] andwere used in this study The concentration of the solutionwas 100mg NO

3

minus Lminus1 The temperature was 20∘C Briefly 5 gof air-dried soil from each soil subsample was equilibratedwith 100mL of NO

3

minus solution Two drops of toluene wereadded to each mixture to prevent any biological NO

3

minus trans-formations Equilibration was estimated to have occurredafter the mixture was shaken on a reciprocal shaker at 20∘Cfor 1 h at a rate of 100 oscillationsmin After equilibrationthe mixtures were centrifuged at 5000 rpm for 10min andthe NO

3

minus concentration of the supernatant was determinedimmediately using a spectrophotometer at 220 nm

The amount of adsorption at equilibrium119876119890(mg gminus1) was

calculated by

119876119890= (119862119894minus 119862119890

119872) times 119881 (1)

where119862119894and119862

119890(mg Lminus1) are the liquid-phase concentrations

of NO3

minus at initial conditions and at equilibrium respectively119881 is the volume of the solution (L) 119872 is the mass of dryadsorbent used (g)

3 Results and Discussion

31 Soil Properties Themain soil properties thought to influ-ence NO

3

minus sorption and movement are provided in Table 1



3

minus



Figure 1 the NO3


3


3


3


3


3


3

minus


3



tion of NO3


3


3


3


0

0005

001

0015

002

0025

003

0035

004

0045

005

0 20 40 60 80 100 120 140Contact time (min)



Sorp

tion

NO

3minus

(mg k

gminus1)



3


0

001

002

003

004

005

006




Sorp

tion

NO

3minus

(mg k

gminus1)




0

001

002

003

004

005

006

007

0 50 100 150 200



Sorp

tion

NO

3minus

(mg k

gminus1)










000086 0001 00012 0002119899 123 127 128 1441198772 099 099 098 099



3

minus


3


3




3


3


3


3





3

minus



minus



3


3

minus



minus Lminus1 NO3


3

minusmgLminus1


minus5

minus45

minus4

minus35

minus3

minus25

minus23 35 4 45 5 55



ln Ce

ln Q

a




1000

1500

2000

2500

3000

3500

0 50 100 150 200Qe (mgL)

QaQ

e(g

Lminus1)








minus


3



3


3


119890119876119890=

1119876119898119887 + 119862

119890119876119898 where 119862


of NO3


3

minus



119898and 119870

119871




119898was greatest





119890) = ln(119870

119865) +

(1119899) ln(119862119890) where 119902


3


3


119890) versus ln(119862

119890)


3


119865)


4 Conclusion



3


3


3


3


the majority of NO3


3


3


References


































Journal of












Volume 2014

Advances in









Geophysics
















3

minus



Figure 1 the NO3


3


3


3


3


3


3

minus


3



tion of NO3


3


3


3


0

0005

001

0015

002

0025

003

0035

004

0045

005

0 20 40 60 80 100 120 140Contact time (min)



Sorp

tion

NO

3minus

(mg k

gminus1)



3


0

001

002

003

004

005

006




Sorp

tion

NO

3minus

(mg k

gminus1)




0

001

002

003

004

005

006

007

0 50 100 150 200



Sorp

tion

NO

3minus

(mg k

gminus1)










000086 0001 00012 0002119899 123 127 128 1441198772 099 099 098 099



3

minus


3


3




3


3


3


3





3

minus



minus



3


3

minus



minus Lminus1 NO3


3

minusmgLminus1


minus5

minus45

minus4

minus35

minus3

minus25

minus23 35 4 45 5 55



ln Ce

ln Q

a




1000

1500

2000

2500

3000

3500

0 50 100 150 200Qe (mgL)

QaQ

e(g

Lminus1)








minus


3



3


3


119890119876119890=

1119876119898119887 + 119862

119890119876119898 where 119862


of NO3


3

minus



119898and 119870

119871




119898was greatest





119890) = ln(119870

119865) +

(1119899) ln(119862119890) where 119902


3


3


119890) versus ln(119862

119890)


3


119865)


4 Conclusion



3


3


3


3


the majority of NO3


3


3


References


































Journal of












Volume 2014

Advances in









Geophysics















0

001

002

003

004

005

006

007

0 50 100 150 200



Sorp

tion

NO

3minus

(mg k

gminus1)










000086 0001 00012 0002119899 123 127 128 1441198772 099 099 098 099



3

minus


3


3




3


3


3


3





3

minus



minus



3


3

minus



minus Lminus1 NO3


3

minusmgLminus1


minus5

minus45

minus4

minus35

minus3

minus25

minus23 35 4 45 5 55



ln Ce

ln Q

a




1000

1500

2000

2500

3000

3500

0 50 100 150 200Qe (mgL)

QaQ

e(g

Lminus1)








minus


3



3


3


119890119876119890=

1119876119898119887 + 119862

119890119876119898 where 119862


of NO3


3

minus



119898and 119870

119871




119898was greatest





119890) = ln(119870

119865) +

(1119899) ln(119862119890) where 119902


3


3


119890) versus ln(119862

119890)


3


119865)


4 Conclusion



3


3


3


3


the majority of NO3


3


3


References


































Journal of












Volume 2014

Advances in









Geophysics















minus5

minus45

minus4

minus35

minus3

minus25

minus23 35 4 45 5 55



ln Ce

ln Q

a




1000

1500

2000

2500

3000

3500

0 50 100 150 200Qe (mgL)

QaQ

e(g

Lminus1)








minus


3



3


3


119890119876119890=

1119876119898119887 + 119862

119890119876119898 where 119862


of NO3


3

minus



119898and 119870

119871




119898was greatest





119890) = ln(119870

119865) +

(1119899) ln(119862119890) where 119902


3


3


119890) versus ln(119862

119890)


3


119865)


4 Conclusion



3


3


3


3


the majority of NO3


3


3


References


































Journal of












Volume 2014

Advances in









Geophysics
















minus


3



3


3


119890119876119890=

1119876119898119887 + 119862

119890119876119898 where 119862


of NO3


3

minus



119898and 119870

119871




119898was greatest





119890) = ln(119870

119865) +

(1119899) ln(119862119890) where 119902


3


3


119890) versus ln(119862

119890)


3


119865)


4 Conclusion



3


3


3


3


the majority of NO3


3


3


References


































Journal of












Volume 2014

Advances in









Geophysics

































Journal of












Volume 2014

Advances in









Geophysics


















Journal of












Volume 2014

Advances in









Geophysics














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