Research ArticlePotential of Controlled Irrigation and Drainage for ReducingNitrogen Emission from Rice Paddies in Southern China
Guang-cheng Shao1 Ming-hui Wang1 Shuang-en Yu1 Na Liu2
Meng-hua Xiao1 and Min Yuan1
1Key Laboratory of Efficient Irrigation-Drainage and Agricultural Soil-Water Environment in Southern China Ministry of EducationCollege of Water Conservancy and Hydropower Engineering Hohai University Nanjing 210098 China2School of Economics and Management Nanjing University of Information Science amp Technology Nanjing 210044 China
Correspondence should be addressed to Guang-cheng Shao sgclnszjgmailcom
Received 11 December 2014 Revised 26 January 2015 Accepted 26 January 2015
Academic Editor Jun Wu
Copyright copy 2015 Guang-cheng Shao et al This is an open access article distributed under the Creative Commons AttributionLicense which permits unrestricted use distribution and reproduction in any medium provided the original work is properlycited
The effect of controlled irrigation and drainage (CID) at different growth stages of rice on nitrogen (N) from rice paddy was studiedSubmergence at different stages was imposed in specially designed experimental tanks in 2009 and 2010 based on alternate wettingand drying technology (AWD the control CK) Treatments include CID treatment at tiller stage (T1) jointing-booting stage (T2)panicle initiation stage (T3) and milky stage (T4) Results showed that fertilization could significantly increase the concentrationof NH
4
+-N and TN in surface water but had a little influence on NO3
minus-N The concentrations of NH4
+-N and NO3
minus-N in surfacewater increased at first and then decreased after fertilization while the concentrations of NH
4
+-N and TN in groundwater kept onbeing relatively stable Compared to CK CID significantly increased the concentration of NH
4
+-N in surface water at four stagesHowever it reduced the concentration of NO
3
minus-N Consistent with the reduction of drainage CID at four stages could significantlydecrease the amount of NH
4
+-N and NO3
minus-N losses by runoff in relation to CK
1 Instruction
Rice (Oryza sativa L) is the staple food for the populationthat lives in China The rice season in Southern Chinacoincideswith the summerwet season and the annual averageprecipitation ismore than 1000mmDrainage is an importantmeasure to allow timely field operation and protect field ricefromwaterlogging However irrational drainage shortens theresidence time of water in the biologically active unsaturatedzone and substantially alters the water regime This resultsin an increase in nitrate losses from the agricultural fieldsto surface recipients [1 2] Moreover the excessive use ofthe N fertilizers has also accelerated the loss of N enteringambient water bodies through various means [3] In a paddy-irrigation district the quantity and quality of drainage waterare primarily controlled by irrigation and fertilization activ-ities and transport of non-point-source pollution is largelydependent on the drainage process [4]
Decreasing water availability for agriculture threatensirrigated rice productivity and ways must be sought to
reduce irrigation water demands while maintaining grainyield of rice [5ndash7] Several water-saving technologies suchas alternate wetting and drying (AWD) and aerobic rice arebeing developed to lower the water requirements of rice crop[6] Attempts to reduce nutrient losses in drainage water haveled to the development of controlled drainage Controlledirrigation and drainage (CID) aims to take advantage of bothalternate wetting and drying and controlled drainage WithCID a higher water depth is maintained and more drainagewater is captured during rain events than with AWD Underthis water management practice more surface runoff is cap-tured in paddy field for later use during moisture deficit peri-odsWhenCIDwas imposed on rice plants at different stagesthey experience two environmental changes the change fromaerobic to anaerobic conditions and the subsequent changefrom anaerobic to aerobic conditions when the floodwaterrecedes [8] The resultant soil-water atmosphere system ishighly complex and heterogeneous in nature [9] Soil underCID at the time of crop growth can trigger several physic-ochemical and microbiological processes The behavior of
Hindawi Publishing CorporationJournal of ChemistryVolume 2015 Article ID 913470 9 pageshttpdxdoiorg1011552015913470
2 Journal of Chemistry
nitrogen under CID is markedly different from its behaviorunder AWD Understanding the N change processes underCID would greatly facilitate regulating N losses from ricepaddy and increase the availability of N
Under CID conditions a higher water depth is main-tained resulting in an increase in soil moisture which wasmore conducive to microbial denitrification [10] Ammoni-acal N is subject to fixation by clays loss by volatilizationleaching runoff seepage and nitrification followed by lossthrough denitrification In flooded paddy soils after trappedmolecular oxygen (O
2) has been quickly consumed sequen-
tial reduction of the following soil oxidants progresses inaccordance with thermodynamic theory nitrate (NO
3
minus)manganese (IV) (Mn
4
+) ferric iron (Fe3+) sulfate (SO4
2minus)and CO
2[11] Partly submergence can result in the accumu-
lation of NH4
+-N the instability of NO3
minus-N and a loweredN requirement for organic matter decomposition Studiesdemonstrated significant reductions of nitrate in drainagewater discharged from controlled drainage systems as a resultof reduced drainage flow and lower concentrations in theshallow groundwater [12] Field data and modeling withHydrus-2D by Hesterberg et al [13] have shown how thecomposition of the drainagewater varies as a result of changesin the flow pattern associated with transient water tables andvariation in concentrations with depth in the soil profileHuang et al [14] showed that agricultural loss of nitrogen andcumulative runoff were positively related through the indoorrainfall simulation test Wesstrom and Messing [15] reported79 and 94 reductions in drain outflows for successiveyears following controlled drainage implementation Theseoutflows significantly reducedNandnitrate (NO
3
minus-N) lossesIn North Carolina several studies showed that controlleddrainage can decrease drain outflow volumes and annualnitrogen (N) [16] Similarly Lalonde et al [12] showed drainflow and NO
3
minus-N reductions for variable riser heights of 58ndash63 and 69ndash76 respectively
Based on the understanding of N transformation pro-cesses water levelmanagement can be developed tominimizefertilizer and water N loss and increase efficiency of thisimportant nutrient element in Southern China Here we pre-sented field measurements of N from rice paddy under con-trolled irrigation and drainage in SouthernChina in 2009 and2010 The main objectives of this study are to gain an insightinto a complete accounting of nitrogen change from ricepaddy under CID and thereby to examine if CID could be aneffective option for mitigating environmental pollution Wehypothesize that plots have the same seepage and percolationrates when a water table existed at the soil surface and watertable recession occurs evenly when floodwater recedes
2 Experimental Design and Methods
21 Experimental Site and the Soil Properties The experi-ments were conducted in specially designed experimentaltanks at the Key Laboratory of Efficient Irrigation-DrainageandAgricultural Soil-Water Environment in SouthernChinaMinistry of Education (Nanjing latitude 31∘571015840 N longitude118∘501015840 E and 144m above sea level) during the rice growing
seasons (May to October) of 2009 and 2010 The region has asubtropical humidmonsoon climate with the average annualevaporation of 900mm and annual mean temperature of154∘C and themaximum andminimumair temperatures are430∘C and minus140∘C respectively The mean annual rainfallfrom 1951 to 2009 is 1051mm where more than 60 ofprecipitation falls in the rainy season and the precipitationis concentrated in the months of MayndashSeptember The frost-free period is 220 days per yearThe soil in the area is a typicalpermeable paddy soil formed on loess deposits with loamyclay There are 15 fixed tanks plots with specifications for thelength times width times depth = 25m times 2m times 2m The irrigationsystem is automatic irrigation system controlled by the host-electromagnetic valve The soil (0ndash30 cm) in tanks with pHvalue of 697 contained 219 of soil organic matter 091 gkgof total nitrogen 2765mgkg of available nitrogen 032 gkgof total phosphorus and 125mgkg of available phosphorus
22 Experimental Design The paddy tanks were 2m wide25m long and 2m high containers constructed from con-crete block and sealedwith awaterproof paint (Figure 1) PVCpipe connected supply and drainage holes in the tanks to 3mhigh bottles which were connected with a tank that suppliedwater The bottom of each tank was filled with a 20 cm layerof coarse gravel separated from the soil by a water-permeablemembrane to allow free supply and drainage When rainfallincreased water depth beyond the upper designated waterlevel drainage occurred Groundwater level was changed byraising or lowering the height of the float valve that controlledthe solenoid valve for each treatment (Figure 1) Whenthe ponded water depth dropped to the lower water levelirrigation water was added with autoirrigation system untilthe upper water table limit was reached Five treatments wereused to evaluate the effects of CID at four stages on the changeof concentration of N during the 2009 and 2010 experiments(Table 1) The tank water depth of AWD treatment was keptbetween minus200mm and 20mm from the soil surface (thecontrol) at tillering stage and between minus300mm and 30mmat other stages Two levels of pondedwater depthwere appliedfor 10 days at tillering stage jointing-booting stage andpanicle initiation stage plus for 14 d at milky stage
23 Plant Material and Cultivated Practices Yangjing 4038high-yielding rice currently used in local production wasgrown in the paddy tanks Seedlings were raised in a seedbedand sowing dates were May 11 2009 and May 15 2010Seedlings were transplanted on June 14 2009 and June 292010 at a hill spacing of 025m times 020m with three seedlingsper hill A week before transplanting the experimental plotswere dry-ploughed and harrowed The soil was soaked 1 daybefore transplanting and then flooded for about 1 week witha 2-3 cm water layer to promote good crop establishmentApplications of fertilizer (N-P
2O5-K2O 15 15 15) at the rate
of 1200 kgha in the formof compound fertilizerwere appliedin three equal splits Plants were harvested on October 232009 and October 29 2010 All other recommended cul-tivated practices for achieving maximum grain yield werefollowed
Journal of Chemistry 3
TDR probes
Experimentaltank
Autoirrigationsystem
Conduit pipe
Solenoid value
Conduit pipe
Supply and drainage unit
Controlcircuit
Finger ofelectromagnetic
valve
supplying waterBox for
Figure 1 Schematic diagram of the experimental set-up placed in the tank
Table 1 Design of controlled irrigation and drainage (CID) scheduling
Treatments Tillering stage Jointing-booting stage Panicle initiation stage Milky stageT1 120mm (10 d) minus300mmsim30mm minus300mmsim30mm minus300mmsim30mmT2 minus200mmsim20mm 250mm (10 d) minus300mmsim30mm minus300mmsim30mmT3 minus200mmsim20mm minus300mmsim30mm 250mm (10 d) minus300mmsim30mmT4 minus200mmsim20mm minus300mmsim30mm minus300mmsim30mm 250mm (14 d)CK minus200mmsim20mm minus300mmsim30mm minus300mmsim30mm minus300mmsim30mmNote minus119868mmsim119869mm denotes that water depth was kept between ndash119868mm and 119869mm at four stages of paddy rice at normal time when water level lowered tominus119868mm irrigation water is added until water table reached 119869mm 119870mm (119867d) indicates that 119870mm fixed water level was kept with duration of 119867 days atfour stages of paddy rice from the soil surface The allowable variation of fixed water level was plusmn5mm during the period of implementation The maximumwater height after rainfall for the control is 50mm at the tillering stage and 100mm at other stages When rainfall increased water depth beyond the designedvalue drainage occurs 4mm water leakage per day was kept when water table existed at soil surface AWD indicates alternate wetting and drying irrigationCID-Stage I CID-Stage II CID-Stage III and CID-Stage IV denote the CID treatments at tillering stage (Stage I) jointing-booting stage (Stage II) panicleinitiation stage (Stage III) and milky stage (Stage IV) respectively
24 Sample Collection and Measurement Field water depthwas observed at 9 orsquoclock by ruler When the minimum levelwas reached the autoirrigation system would irrigate untilwater level reached maximum level Similarly when waterlevel exceeded maximum level due to rainfall the drainagevolume was subsequently calculated by counting the numberof solenoid valves opened and stored by a datalogger Watersamples were collected in the polyethylene bottle for fourtimes during the submergence period The surface water wascollected by the 50mL syringe (without disturbing the soiland selecting the top surfacewater randomly) rinse all bottlesfirstly and then take the appropriate amount of water sampleThe subsurface water was collected by the undergrounddrainage pipe The water samples were analyzed for ammo-nium nitrogen (NH
4
+-N) and nitrate nitrogen (NO3
minus-N) byusing a Shimadzu UV-2800 spectrophotometer In accor-dance with ldquowater and wastewater monitoring and analysismethodsrdquo alkaline per sulfate digestion and Nesslerrsquos reagentcolorimetric phenol disulfonic acid spectrophotometer wereused to analyze total nitrogen in water test (TN) ammonia(NH4
+-N) andnitrate (NO3
minus-N) contentTheN loss throughrunoffwas calculated as the product of NH
4
+-N andNO3
minus-Nconcentration in runoff and the amount of runoff
25 Statistical Analysis We used a randomized completeblock design with three replications Treatment effects wereanalyzed using analysis of variance (ANOVA) procedure ofSPSS software version 140 Treatment means were separatedby least significant difference (LSD) test at 119875 le 005 unlessotherwise specified
3 Results
31 The Change of the Concentration of NH4+-N NO3
minus-Nand TN after Fertilization Concentrations of NH
4
+-N andNO3
minus-N andTN in surfacewater and groundwaterweremea-sured after fertilization application from tillering to jointing-booting stage in 2009 and 2010 (Figure 2 and Table 2) Afterfertilization application at tillering stage the highest con-centration of NH
4
+-N in surface water was obtained on thesecond day while for NO
3
minus-N the highest concentration wasobserved on the third day (Figures 2(a)ndash2(d)) The averageconcentration of NH
4
+-N and NO3
minus-N in the surface waterof paddy decreased dramatically after 7 days of submergenceGenerally the high rates of N application generally resultedin high concentrations of TN in the surface water especially
4 Journal of Chemistry
0
10
20
30
40
50
SurfaceUnderground
630 736282009
627
NH
4
+-N
(mgmiddot
Lminus1)
(a)
79762010
71275
SurfaceUnderground
0
10
20
30
40
50
NH
4
+-N
(mgmiddot
Lminus1)
(b)
SurfaceUnderground
0
03
06
09
12
15
18
627 630 736282009
NO
3
minus-N
(mgmiddot
Lminus1)
(c)
79 71276752010
SurfaceUnderground
0
03
06
09
12
15
18N
O3
minus-N
(mgmiddot
Lminus1)
(d)
0
20
40
60
627 630 736282009
SurfaceUnderground
TN (m
gmiddotLminus
1)
(e)
79 71276752010
SurfaceUnderground
0
20
40
60
TN (m
gmiddotLminus
1)
(f)
Figure 2 The change of the concentration of NH4
+-N NO3
minus-N and TN after fertilization at tillering stage in 2009 and 2010
Journal of Chemistry 5
Table 2The change of the concentration of NH4
+-N NO3
minus-N andTN after fertilization at tillering stage in 2010
within 7 days after N application which showed the increas-ing potential of N loss by runoff (Figures 2(e)-2(f)) Theconcentration of NH
4
+-N and TN in underground watershowed more stability than those in surface water afterfertilizer applicationThe concentration ofNO
3
minus-N in under-ground water reached the maximum on the second day andthen declinewith time passing During the period of jointing-booting the highest concentrations of NH
4
+-N and NO3
minus-Nin surface water were observed on the third day after applyingfertilization while for TN the highest concentration wasobtained on the fifth day (Table 2) The difference betweentillering and jointing-booting stages may be attributed todifferent absorption during crop growth and environmentalfactors The change of concentration of NH
4
+-N and NO3
minus-N in underground water demonstrated similar trend to theconcentration of TN in surface water The concentration ofTN within 7 days after N application was not significantlydifferent
32 The Change of Concentration of NH4+-N during Submer-
gence The concentration of NH4
+-N under CK increasedwith the time of submergence and reaches the maximum atthe tenth day at tillering stage (Figure 3(a))The average con-centration of NH
4
+-N under T1 was 400 higher than thatunder CK on the first day after submergence The differencesin the concentration of NH
4
+-N between T1 and CK weresignificant at four timesrsquo measurements As is shown inFigure 3(b) the concentration of NH
4
+-N under CK and T2demonstrated the decline trend with time going on This isbecause the crop absorbed some NH
4
+-N during submer-gence and resulted in the gradual decline of the concentrationof NH
4
+-N There were not significant differences in theconcentration ofNH
4
+-NbetweenT2 andCKThedynamiticchanges of the concentration of NH
4
+-N at panicle initiationstage during submergence were showed in Figure 3(c) Theconcentration of NH
4
+-N under T3 and CK reached themaximum after 3-day submergence and then decreased astime goes on T3 significantly increased the concentration ofNH4
+-N during the submergence compared to CK Duringthe submergence at milky stage the concentrations of NH
4
+-N under CK and T4 showed a trend of rise first and thenfall (Figure 3(d)) Compared with CK submergence at milkystage also significantly increased the concentration of NH
4
+-N
33 The Change of Concentration of NO3minus-N during Sub-
mergence The dynamitic changes of NO3
minus-N in surfacewater after submergence at four stages in 2010 were shownin Figure 4 Submergence at tillering stage increased theconcentration of NO
3
minus-N but the difference between T1 andCK was not significant (Figure 4(a)) The concentration ofNO3
minus-N for T1 declined with prolonged submergence Theconcentration ofNO
3
minus-NunderT1 at the end of submergencedecreased to 38 of that on the first day The concentrationsof NO
3
minus-N at jointing-booting stage were averagely lowerthan that at tillering stage It is because rice grew rapidly atjointing-booting stage and absorbed more nitrogen resultingin the reduction in the concentration of NO
3
minus-N Submer-gence at jointing-booting stage significantly reduced the con-centration of NO
3
minus-N (Figure 4(b)) As shown in Figure 4(c)NO3
minus-N concentrations under the treatment T3 were lowerthan those under CK treatment during the submergenceexcept at the eighth day The concentration of NO
3
minus-N wasnot significantly decreased by submergence compared to CKAt milky stage it was observed that the concentration ofNO3
minus-N under T4 showed the trend of rise after first declineThis may be attributed to the decomposition of leaves sub-merged in water at milky stage The differences in the con-centration of NO
3
minus-N between T4 and CK were significant(Figure 4(d))
34 Potential of NH4+-N and NO3
minus-N Loss by Runoff duringSubmergence NH
4
+-N and NO3
minus-N losses by runoff indifferent treatments as influenced by submergence at differentstages during the year of 2010 were presented in Table 3 Aswas the case with surface water NH
4
+-N was the major com-ponent ofN in runoffwater RegardingNH
4
+-N andNO3
minus-Nloss by runoff at tillering stage the amount was decreased by76 and 83 by submergence (T1) as compared with the CKtreatment respectively The NH
4
+-N loss under T2 T3 andT4 was only 24 53 and 12 respectively of that underCK CID at jointing-booting panicle initiation and milkystages also decreases the amount of NO
3
minus-N loss by 91 91and 85 in relation to CK
4 Discussion
The increased attention being paid to the loss of nitrate viaagricultural drainage has led many to call for significantchanges in both management of N fertilizer and manage-ment of agricultural drainage systems [17] Overall currentagronomic guidelines which are primarily based on cropresponse may inadequately protect the water quality inSouthern China [18] Although positive results were obtainedby applying AWD technology in rice fields the drainagevolume in AWD has been reported to be larger due to theexcessive drainage requirement which results in an increasein nitrate losses from the agricultural fields [19 20] This canbe partially addressed by the introduction of irrigation anddrainage management This then allows drainage design andmanagement within the reasonable bounds expected forlong-term nitrate control [21]
6 Journal of Chemistry
00
10
20
30
40
50
CKT1
722 725 728719
NH
4
+-N
(mgmiddot
Lminus1)
(a)
814 817 820
CKT2
00
10
20
30
40
50
NH
4
+-N
(mgmiddot
Lminus1)
823
(b)
00
10
20
30
40
50
830 92 95 98
CKT3
NH
4
+-N
(mgmiddot
Lminus1)
(c)
CKT4
912 915 918 92100
10
20
30
40
50N
H4
+-N
(mgmiddot
Lminus1)
(d)
Figure 3 The change of the concentration of NH4
+-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
The various forms of N caused by the actions of microor-ganisms are dependent on temperature and time The sub-sequent movement of nitrate is dependent on the presenceof water in excess of field capacity This timing should corre-spond with the plantrsquos need for N Logically placement of Ninto the soil profile as a fertilizer addition would ideally be asclose to the time that a plant needs the nutrient as possibleto minimize the chance for loss into the environment In thisexperiment we observed that urea fertilization can signifi-cantly increase the concentration of NH
4
+-N and TN but hasa little influence on NO
3
minus-NThe major nitrogen treatment mechanisms of rice paddy
include microbial interactions with nitrogen sedimentation
chemical adsorption and plant uptake [22] In tradi-tional nitrogen treatments the biological nitrogen transitionrequires a two-step process nitrification followed by denitri-fication Nitrification implies a chemolithoautotrophic oxida-tion of ammonia to nitrate under strict aerobic conditionsThe nitrification process is very oxygen demanding Duringthe submergence the biological denitrification mechanismmakes use of nitrate as the terminal electron acceptor inlow-oxygen environments [23] Under CID condition theconcentrations of NH
4
+-N at four stages were higher thanthat of NO
3
minus-N As is shown in Table 3 NH4
+-N was themajor component of N in runoff water after submergenceSimilar results were also reported in paddy soil in Southern
Journal of Chemistry 7
00
03
06
09
12
15
CKT1
719 725 728722
NO
3
minus-N
(mgmiddot
Lminus1)
(a)
823
CKT2
82081781400
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(b)
00
03
06
09
12
15
9592830 98
CKT3
NO
3
minus-N
(mgmiddot
Lminus1)
(c)
918915912 921
CKT4
00
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(d)
Figure 4The change of the concentration of NO3
minus-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
Table 3 Nitrogen loss by runoff during the period of submergence in 2010
Form of N Tillering stage Jointing-booting stage Panicle initiation stage Milky stageT1 CK T2 CK T3 CK T4 CK
minus-N (gha) 36 plusmn 21 214 plusmn 102 42 plusmn 53 485 plusmn 198 84 plusmn 48 910 plusmn 438 30 plusmn 18 196 plusmn 93Note CK indicates alternate drying and wet irrigation T1 T2 T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiationstage and milky stage respectively Each value is the mean plusmn SD (119899 = 3)
China [24]This is because the nitrificationwas suppressed bylack of oxygen due to prolonged submergence The concen-tration of NH
4
+-N in surface water at tillering stage is higherthan that at the following three stages This is because thegrowth is strong at jointing-booting and panicle initiationstages which lead to the reduction of NH
4
+-N and NO3
minus-N
Generally nitrogen loss through drainage increases as Nrate and runoff volume increase especially as N rates aregreater than the economic optimum CID had been shownto decrease water flow [25] and thus supports results fromthis study Compared to CK the CID treatment significantlydecreases the loss of NH
4
+-N and NO3
minus-N indicating that
8 Journal of Chemistry
NH4
+-N and NO3
minus-N loads in the runoff were not only cor-related with runoff volume but also pertinent to NH
4
+-N andNO3
minus-N concentrations during given runoff eventsThis study only investigated the potential of CID at single
stage for reducing nitrogen emission from rice paddies inSouthern China It did not investigate the effect of CID at thecompound stages and the multistages and change of N aftersubmergence withdrawal More research needs to be carriedout in the future to define these relationships
5 Conclusions
In Southern China the water quality in paddy is easilyaffected by various forms ofNThe high rates of N applicationgenerally resulted in high concentrations of NH
4
+-N and TNin the surface water on the second day indicating the periodwith the highest risk of N runoff Compared to CK the con-centration of NO
3
minus-N in surface water showed some reduc-tion under CID at four stages but differed largely among thetreatments NH
4
+-Nwas themajor component of N in runoffwater after submergence at four stages Consistent with thereduction of drainage CID at four stages can significantlydecrease the amount of NO
3
minus-N and NH4
+-N losses byrunoff in relation to CK The study can be helpful for waterlevel management in rice paddy with compromise of watersaving reduction of N and high yield
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was funded by Key Program granted by theNational Nature amp Science Foundation of China (nos51479063 51279059 and 41271236) and supported by theSupporting Program of the ldquoOutstanding Young CreativeTalents in Hohai Universityrdquo ldquoOutstanding Scientific andTechnological Innovation Team in Jiangsu Colleges and Uni-versitiesrdquo and ldquothe Priority Academic Program Developmentof JiangsuHigher Education InstitutionsrdquoThe authors extendtheir gratitude to editor and the anonymous reviewers forsubstantial comments on earlier versions of this paper
References
[1] R W Skaggs D Amatya R O Evans and J E Parsons ldquoChar-acterization and evaluation of proposed hydrologic criteria forwetlandsrdquo Journal of Soil andWater Conservation vol 49 no 5pp 501ndash510 1994
[2] G W Randall and J A Vetsch ldquoNitrate losses in subsurfacedrainage from a corn-soybean rotation as affected by fall andspring application of nitrogen and nitrapyrinrdquo Journal of Envi-ronmental Quality vol 34 no 2 pp 590ndash597 2005
[3] N Chirinda J E Olesen J R Porter and P Schjoslashnning ldquoSoilproperties crop production and greenhouse gas emissions fromorganic and inorganic fertilizer-based arable cropping systemsrdquo
[4] K Wang R D Zhang and H Chen ldquoDrainage-process anal-yses for agricultural non-point-source pollution from irrigatedpaddy systemsrdquo Journal of Irrigation and Drainage Engineeringvol 140 Article ID 04013004 pp 1ndash14 2014
[5] P Belder B AM Bouman R Cabangon et al ldquoEffect of water-saving irrigation on rice yield and water use in typical lowlandconditions in AsiardquoAgriculturalWaterManagement vol 65 no3 pp 193ndash210 2004
[6] B A M Bouman ldquoA conceptual framework for the improve-ment of crop water productivity at different spatial scalesrdquoAgricultural Systems vol 93 no 1ndash3 pp 43ndash60 2007
[7] B A M Bouman E Humphreys T P Tuong and R BarkerldquoRice and waterrdquo Advances in Agronomy vol 92 pp 187ndash2372007
[8] G Shao J Cui S Yu et al ldquoImpacts of controlled irrigationand drainage on the yield and physiological attributes of riceImpacts of controlled irrigation and drainage on the yield andphysiological attributes of ricerdquo Agricultural Water Manage-ment vol 149 pp 156ndash165 2015
[9] K Surajit and D De Principles and Practices of Rice ProductionJohn Wiley amp Sons New York NY USA 1981
[10] C-G Lee T D Fletcher and G Sun ldquoNitrogen removal in con-structedwetland systemsrdquoEngineering in Life Sciences vol 9 no1 pp 11ndash22 2009
[11] Y Takai and T Kamura ldquoThe mechanism of reduction inwaterlogged paddy soilrdquo Folia Microbiologica vol 11 no 4 pp304ndash313 1966
[12] V Lalonde C A Madramootoo L Trenholm and R SBroughton ldquoEffects of controlled drainage onnitrate concentra-tions in subsurface drain dischargerdquo Agricultural Water Man-agement vol 29 no 2 pp 187ndash199 1996
[13] D Hesterberg B de Vos and P A C Raats ldquoChemistry ofsubsurface drain discharge from an agricultural polder soilrdquoAgricultural Water Management vol 86 no 1-2 pp 220ndash2282006
[14] M X Huang S Zhang Y J Tang and B X Chen ldquoNitrogenlosses from farm runoff under simulated rainfall conditionsrdquoSoil and Environmental Sciences vol 10 no 1 pp 6ndash10 2001
[15] IWesstrom and IMessing ldquoEffects of controlled drainage onNand P losses andNdynamics in a loamy sandwith spring cropsrdquoAgricultural Water Management vol 87 no 3 pp 229ndash2402007
[16] R O Evans R W Skaggs and J W Gilliam ldquoControlledversus conventional drainage effects on water qualityrdquo Journalof Irrigation and Drainage Engineering vol 121 no 4 pp 271ndash276 1995
[17] G W Randall and D J Mulla ldquoNitrate nitrogen in surfacewaters as influenced by climatic conditions and agriculturalpracticesrdquo Journal of Environmental Quality vol 30 no 2 pp337ndash344 2001
[18] Y-Q Zhang M-X Wen X-P Li and X-J Shi ldquoLong-termfertilisation causes excess supply and loss of phosphorus inpurple paddy soilrdquo Journal of the Science of Food andAgriculturevol 94 no 6 pp 1175ndash1183 2014
[19] X Guo J Yuan F Guo and Z Chen ldquoPreliminary study onwater-catching and controlled irrigation technology of ricerdquoTransactions of the Chinese Society of Agricultural Engineeringvol 25 no 4 pp 70ndash73 2009
Journal of Chemistry 9
[20] S E Yu Z M Miao W G Xing G C Shao and Y X JiangldquoResearch advance on irrigation and drainage for rice by usingfield water level as regulation indexrdquo Journal of Irrigation andDrainage vol 29 pp 134ndash136 2010 (Chinese)
[21] J E Ayars E W Christen and J W Hornbuckle ldquoControlleddrainage for improved water management in arid regionsirrigated agriculturerdquo Agricultural Water Management vol 86no 1-2 pp 128ndash139 2006
[22] N R Khatiwada andC Polprasert ldquoAssessment of effective spe-cific surface area for free water surface constructed wetlandsrdquoWater Science and Technology vol 40 no 3 pp 83ndash89 1999
[23] M Prosnansky Y Sakakibara and M Kuroda ldquoHigh-rate den-itrification and SS rejection by biofilm-electrode reactor (BER)combined with microfiltrationrdquoWater Research vol 36 no 19pp 4801ndash4810 2002
[24] X J Hu X H Shao Y Y Li J He S G Lu and Y Qiu ldquoEffectsof controlled and mid-gathering irrigation mode of paddy riceon the pollutants emission and reductionrdquo Energy Procedia vol16 pp 907ndash914 2012
[25] G-C Shao S Deng N Liu S-E Yu M-H Wang and D-LShe ldquoEffects of controlled irrigation and drainage on growthgrain yield and water use in paddy ricerdquo European Journal ofAgronomy vol 53 pp 1ndash9 2014
nitrogen under CID is markedly different from its behaviorunder AWD Understanding the N change processes underCID would greatly facilitate regulating N losses from ricepaddy and increase the availability of N
Under CID conditions a higher water depth is main-tained resulting in an increase in soil moisture which wasmore conducive to microbial denitrification [10] Ammoni-acal N is subject to fixation by clays loss by volatilizationleaching runoff seepage and nitrification followed by lossthrough denitrification In flooded paddy soils after trappedmolecular oxygen (O
2) has been quickly consumed sequen-
tial reduction of the following soil oxidants progresses inaccordance with thermodynamic theory nitrate (NO
3
minus)manganese (IV) (Mn
4
+) ferric iron (Fe3+) sulfate (SO4
2minus)and CO
2[11] Partly submergence can result in the accumu-
lation of NH4
+-N the instability of NO3
minus-N and a loweredN requirement for organic matter decomposition Studiesdemonstrated significant reductions of nitrate in drainagewater discharged from controlled drainage systems as a resultof reduced drainage flow and lower concentrations in theshallow groundwater [12] Field data and modeling withHydrus-2D by Hesterberg et al [13] have shown how thecomposition of the drainagewater varies as a result of changesin the flow pattern associated with transient water tables andvariation in concentrations with depth in the soil profileHuang et al [14] showed that agricultural loss of nitrogen andcumulative runoff were positively related through the indoorrainfall simulation test Wesstrom and Messing [15] reported79 and 94 reductions in drain outflows for successiveyears following controlled drainage implementation Theseoutflows significantly reducedNandnitrate (NO
3
minus-N) lossesIn North Carolina several studies showed that controlleddrainage can decrease drain outflow volumes and annualnitrogen (N) [16] Similarly Lalonde et al [12] showed drainflow and NO
3
minus-N reductions for variable riser heights of 58ndash63 and 69ndash76 respectively
Based on the understanding of N transformation pro-cesses water levelmanagement can be developed tominimizefertilizer and water N loss and increase efficiency of thisimportant nutrient element in Southern China Here we pre-sented field measurements of N from rice paddy under con-trolled irrigation and drainage in SouthernChina in 2009 and2010 The main objectives of this study are to gain an insightinto a complete accounting of nitrogen change from ricepaddy under CID and thereby to examine if CID could be aneffective option for mitigating environmental pollution Wehypothesize that plots have the same seepage and percolationrates when a water table existed at the soil surface and watertable recession occurs evenly when floodwater recedes
2 Experimental Design and Methods
21 Experimental Site and the Soil Properties The experi-ments were conducted in specially designed experimentaltanks at the Key Laboratory of Efficient Irrigation-DrainageandAgricultural Soil-Water Environment in SouthernChinaMinistry of Education (Nanjing latitude 31∘571015840 N longitude118∘501015840 E and 144m above sea level) during the rice growing
seasons (May to October) of 2009 and 2010 The region has asubtropical humidmonsoon climate with the average annualevaporation of 900mm and annual mean temperature of154∘C and themaximum andminimumair temperatures are430∘C and minus140∘C respectively The mean annual rainfallfrom 1951 to 2009 is 1051mm where more than 60 ofprecipitation falls in the rainy season and the precipitationis concentrated in the months of MayndashSeptember The frost-free period is 220 days per yearThe soil in the area is a typicalpermeable paddy soil formed on loess deposits with loamyclay There are 15 fixed tanks plots with specifications for thelength times width times depth = 25m times 2m times 2m The irrigationsystem is automatic irrigation system controlled by the host-electromagnetic valve The soil (0ndash30 cm) in tanks with pHvalue of 697 contained 219 of soil organic matter 091 gkgof total nitrogen 2765mgkg of available nitrogen 032 gkgof total phosphorus and 125mgkg of available phosphorus
22 Experimental Design The paddy tanks were 2m wide25m long and 2m high containers constructed from con-crete block and sealedwith awaterproof paint (Figure 1) PVCpipe connected supply and drainage holes in the tanks to 3mhigh bottles which were connected with a tank that suppliedwater The bottom of each tank was filled with a 20 cm layerof coarse gravel separated from the soil by a water-permeablemembrane to allow free supply and drainage When rainfallincreased water depth beyond the upper designated waterlevel drainage occurred Groundwater level was changed byraising or lowering the height of the float valve that controlledthe solenoid valve for each treatment (Figure 1) Whenthe ponded water depth dropped to the lower water levelirrigation water was added with autoirrigation system untilthe upper water table limit was reached Five treatments wereused to evaluate the effects of CID at four stages on the changeof concentration of N during the 2009 and 2010 experiments(Table 1) The tank water depth of AWD treatment was keptbetween minus200mm and 20mm from the soil surface (thecontrol) at tillering stage and between minus300mm and 30mmat other stages Two levels of pondedwater depthwere appliedfor 10 days at tillering stage jointing-booting stage andpanicle initiation stage plus for 14 d at milky stage
23 Plant Material and Cultivated Practices Yangjing 4038high-yielding rice currently used in local production wasgrown in the paddy tanks Seedlings were raised in a seedbedand sowing dates were May 11 2009 and May 15 2010Seedlings were transplanted on June 14 2009 and June 292010 at a hill spacing of 025m times 020m with three seedlingsper hill A week before transplanting the experimental plotswere dry-ploughed and harrowed The soil was soaked 1 daybefore transplanting and then flooded for about 1 week witha 2-3 cm water layer to promote good crop establishmentApplications of fertilizer (N-P
2O5-K2O 15 15 15) at the rate
of 1200 kgha in the formof compound fertilizerwere appliedin three equal splits Plants were harvested on October 232009 and October 29 2010 All other recommended cul-tivated practices for achieving maximum grain yield werefollowed
Journal of Chemistry 3
TDR probes
Experimentaltank
Autoirrigationsystem
Conduit pipe
Solenoid value
Conduit pipe
Supply and drainage unit
Controlcircuit
Finger ofelectromagnetic
valve
supplying waterBox for
Figure 1 Schematic diagram of the experimental set-up placed in the tank
Table 1 Design of controlled irrigation and drainage (CID) scheduling
Treatments Tillering stage Jointing-booting stage Panicle initiation stage Milky stageT1 120mm (10 d) minus300mmsim30mm minus300mmsim30mm minus300mmsim30mmT2 minus200mmsim20mm 250mm (10 d) minus300mmsim30mm minus300mmsim30mmT3 minus200mmsim20mm minus300mmsim30mm 250mm (10 d) minus300mmsim30mmT4 minus200mmsim20mm minus300mmsim30mm minus300mmsim30mm 250mm (14 d)CK minus200mmsim20mm minus300mmsim30mm minus300mmsim30mm minus300mmsim30mmNote minus119868mmsim119869mm denotes that water depth was kept between ndash119868mm and 119869mm at four stages of paddy rice at normal time when water level lowered tominus119868mm irrigation water is added until water table reached 119869mm 119870mm (119867d) indicates that 119870mm fixed water level was kept with duration of 119867 days atfour stages of paddy rice from the soil surface The allowable variation of fixed water level was plusmn5mm during the period of implementation The maximumwater height after rainfall for the control is 50mm at the tillering stage and 100mm at other stages When rainfall increased water depth beyond the designedvalue drainage occurs 4mm water leakage per day was kept when water table existed at soil surface AWD indicates alternate wetting and drying irrigationCID-Stage I CID-Stage II CID-Stage III and CID-Stage IV denote the CID treatments at tillering stage (Stage I) jointing-booting stage (Stage II) panicleinitiation stage (Stage III) and milky stage (Stage IV) respectively
24 Sample Collection and Measurement Field water depthwas observed at 9 orsquoclock by ruler When the minimum levelwas reached the autoirrigation system would irrigate untilwater level reached maximum level Similarly when waterlevel exceeded maximum level due to rainfall the drainagevolume was subsequently calculated by counting the numberof solenoid valves opened and stored by a datalogger Watersamples were collected in the polyethylene bottle for fourtimes during the submergence period The surface water wascollected by the 50mL syringe (without disturbing the soiland selecting the top surfacewater randomly) rinse all bottlesfirstly and then take the appropriate amount of water sampleThe subsurface water was collected by the undergrounddrainage pipe The water samples were analyzed for ammo-nium nitrogen (NH
4
+-N) and nitrate nitrogen (NO3
minus-N) byusing a Shimadzu UV-2800 spectrophotometer In accor-dance with ldquowater and wastewater monitoring and analysismethodsrdquo alkaline per sulfate digestion and Nesslerrsquos reagentcolorimetric phenol disulfonic acid spectrophotometer wereused to analyze total nitrogen in water test (TN) ammonia(NH4
+-N) andnitrate (NO3
minus-N) contentTheN loss throughrunoffwas calculated as the product of NH
4
+-N andNO3
minus-Nconcentration in runoff and the amount of runoff
25 Statistical Analysis We used a randomized completeblock design with three replications Treatment effects wereanalyzed using analysis of variance (ANOVA) procedure ofSPSS software version 140 Treatment means were separatedby least significant difference (LSD) test at 119875 le 005 unlessotherwise specified
3 Results
31 The Change of the Concentration of NH4+-N NO3
minus-Nand TN after Fertilization Concentrations of NH
4
+-N andNO3
minus-N andTN in surfacewater and groundwaterweremea-sured after fertilization application from tillering to jointing-booting stage in 2009 and 2010 (Figure 2 and Table 2) Afterfertilization application at tillering stage the highest con-centration of NH
4
+-N in surface water was obtained on thesecond day while for NO
3
minus-N the highest concentration wasobserved on the third day (Figures 2(a)ndash2(d)) The averageconcentration of NH
4
+-N and NO3
minus-N in the surface waterof paddy decreased dramatically after 7 days of submergenceGenerally the high rates of N application generally resultedin high concentrations of TN in the surface water especially
4 Journal of Chemistry
0
10
20
30
40
50
SurfaceUnderground
630 736282009
627
NH
4
+-N
(mgmiddot
Lminus1)
(a)
79762010
71275
SurfaceUnderground
0
10
20
30
40
50
NH
4
+-N
(mgmiddot
Lminus1)
(b)
SurfaceUnderground
0
03
06
09
12
15
18
627 630 736282009
NO
3
minus-N
(mgmiddot
Lminus1)
(c)
79 71276752010
SurfaceUnderground
0
03
06
09
12
15
18N
O3
minus-N
(mgmiddot
Lminus1)
(d)
0
20
40
60
627 630 736282009
SurfaceUnderground
TN (m
gmiddotLminus
1)
(e)
79 71276752010
SurfaceUnderground
0
20
40
60
TN (m
gmiddotLminus
1)
(f)
Figure 2 The change of the concentration of NH4
+-N NO3
minus-N and TN after fertilization at tillering stage in 2009 and 2010
Journal of Chemistry 5
Table 2The change of the concentration of NH4
+-N NO3
minus-N andTN after fertilization at tillering stage in 2010
within 7 days after N application which showed the increas-ing potential of N loss by runoff (Figures 2(e)-2(f)) Theconcentration of NH
4
+-N and TN in underground watershowed more stability than those in surface water afterfertilizer applicationThe concentration ofNO
3
minus-N in under-ground water reached the maximum on the second day andthen declinewith time passing During the period of jointing-booting the highest concentrations of NH
4
+-N and NO3
minus-Nin surface water were observed on the third day after applyingfertilization while for TN the highest concentration wasobtained on the fifth day (Table 2) The difference betweentillering and jointing-booting stages may be attributed todifferent absorption during crop growth and environmentalfactors The change of concentration of NH
4
+-N and NO3
minus-N in underground water demonstrated similar trend to theconcentration of TN in surface water The concentration ofTN within 7 days after N application was not significantlydifferent
32 The Change of Concentration of NH4+-N during Submer-
gence The concentration of NH4
+-N under CK increasedwith the time of submergence and reaches the maximum atthe tenth day at tillering stage (Figure 3(a))The average con-centration of NH
4
+-N under T1 was 400 higher than thatunder CK on the first day after submergence The differencesin the concentration of NH
4
+-N between T1 and CK weresignificant at four timesrsquo measurements As is shown inFigure 3(b) the concentration of NH
4
+-N under CK and T2demonstrated the decline trend with time going on This isbecause the crop absorbed some NH
4
+-N during submer-gence and resulted in the gradual decline of the concentrationof NH
4
+-N There were not significant differences in theconcentration ofNH
4
+-NbetweenT2 andCKThedynamiticchanges of the concentration of NH
4
+-N at panicle initiationstage during submergence were showed in Figure 3(c) Theconcentration of NH
4
+-N under T3 and CK reached themaximum after 3-day submergence and then decreased astime goes on T3 significantly increased the concentration ofNH4
+-N during the submergence compared to CK Duringthe submergence at milky stage the concentrations of NH
4
+-N under CK and T4 showed a trend of rise first and thenfall (Figure 3(d)) Compared with CK submergence at milkystage also significantly increased the concentration of NH
4
+-N
33 The Change of Concentration of NO3minus-N during Sub-
mergence The dynamitic changes of NO3
minus-N in surfacewater after submergence at four stages in 2010 were shownin Figure 4 Submergence at tillering stage increased theconcentration of NO
3
minus-N but the difference between T1 andCK was not significant (Figure 4(a)) The concentration ofNO3
minus-N for T1 declined with prolonged submergence Theconcentration ofNO
3
minus-NunderT1 at the end of submergencedecreased to 38 of that on the first day The concentrationsof NO
3
minus-N at jointing-booting stage were averagely lowerthan that at tillering stage It is because rice grew rapidly atjointing-booting stage and absorbed more nitrogen resultingin the reduction in the concentration of NO
3
minus-N Submer-gence at jointing-booting stage significantly reduced the con-centration of NO
3
minus-N (Figure 4(b)) As shown in Figure 4(c)NO3
minus-N concentrations under the treatment T3 were lowerthan those under CK treatment during the submergenceexcept at the eighth day The concentration of NO
3
minus-N wasnot significantly decreased by submergence compared to CKAt milky stage it was observed that the concentration ofNO3
minus-N under T4 showed the trend of rise after first declineThis may be attributed to the decomposition of leaves sub-merged in water at milky stage The differences in the con-centration of NO
3
minus-N between T4 and CK were significant(Figure 4(d))
34 Potential of NH4+-N and NO3
minus-N Loss by Runoff duringSubmergence NH
4
+-N and NO3
minus-N losses by runoff indifferent treatments as influenced by submergence at differentstages during the year of 2010 were presented in Table 3 Aswas the case with surface water NH
4
+-N was the major com-ponent ofN in runoffwater RegardingNH
4
+-N andNO3
minus-Nloss by runoff at tillering stage the amount was decreased by76 and 83 by submergence (T1) as compared with the CKtreatment respectively The NH
4
+-N loss under T2 T3 andT4 was only 24 53 and 12 respectively of that underCK CID at jointing-booting panicle initiation and milkystages also decreases the amount of NO
3
minus-N loss by 91 91and 85 in relation to CK
4 Discussion
The increased attention being paid to the loss of nitrate viaagricultural drainage has led many to call for significantchanges in both management of N fertilizer and manage-ment of agricultural drainage systems [17] Overall currentagronomic guidelines which are primarily based on cropresponse may inadequately protect the water quality inSouthern China [18] Although positive results were obtainedby applying AWD technology in rice fields the drainagevolume in AWD has been reported to be larger due to theexcessive drainage requirement which results in an increasein nitrate losses from the agricultural fields [19 20] This canbe partially addressed by the introduction of irrigation anddrainage management This then allows drainage design andmanagement within the reasonable bounds expected forlong-term nitrate control [21]
6 Journal of Chemistry
00
10
20
30
40
50
CKT1
722 725 728719
NH
4
+-N
(mgmiddot
Lminus1)
(a)
814 817 820
CKT2
00
10
20
30
40
50
NH
4
+-N
(mgmiddot
Lminus1)
823
(b)
00
10
20
30
40
50
830 92 95 98
CKT3
NH
4
+-N
(mgmiddot
Lminus1)
(c)
CKT4
912 915 918 92100
10
20
30
40
50N
H4
+-N
(mgmiddot
Lminus1)
(d)
Figure 3 The change of the concentration of NH4
+-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
The various forms of N caused by the actions of microor-ganisms are dependent on temperature and time The sub-sequent movement of nitrate is dependent on the presenceof water in excess of field capacity This timing should corre-spond with the plantrsquos need for N Logically placement of Ninto the soil profile as a fertilizer addition would ideally be asclose to the time that a plant needs the nutrient as possibleto minimize the chance for loss into the environment In thisexperiment we observed that urea fertilization can signifi-cantly increase the concentration of NH
4
+-N and TN but hasa little influence on NO
3
minus-NThe major nitrogen treatment mechanisms of rice paddy
include microbial interactions with nitrogen sedimentation
chemical adsorption and plant uptake [22] In tradi-tional nitrogen treatments the biological nitrogen transitionrequires a two-step process nitrification followed by denitri-fication Nitrification implies a chemolithoautotrophic oxida-tion of ammonia to nitrate under strict aerobic conditionsThe nitrification process is very oxygen demanding Duringthe submergence the biological denitrification mechanismmakes use of nitrate as the terminal electron acceptor inlow-oxygen environments [23] Under CID condition theconcentrations of NH
4
+-N at four stages were higher thanthat of NO
3
minus-N As is shown in Table 3 NH4
+-N was themajor component of N in runoff water after submergenceSimilar results were also reported in paddy soil in Southern
Journal of Chemistry 7
00
03
06
09
12
15
CKT1
719 725 728722
NO
3
minus-N
(mgmiddot
Lminus1)
(a)
823
CKT2
82081781400
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(b)
00
03
06
09
12
15
9592830 98
CKT3
NO
3
minus-N
(mgmiddot
Lminus1)
(c)
918915912 921
CKT4
00
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(d)
Figure 4The change of the concentration of NO3
minus-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
Table 3 Nitrogen loss by runoff during the period of submergence in 2010
Form of N Tillering stage Jointing-booting stage Panicle initiation stage Milky stageT1 CK T2 CK T3 CK T4 CK
minus-N (gha) 36 plusmn 21 214 plusmn 102 42 plusmn 53 485 plusmn 198 84 plusmn 48 910 plusmn 438 30 plusmn 18 196 plusmn 93Note CK indicates alternate drying and wet irrigation T1 T2 T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiationstage and milky stage respectively Each value is the mean plusmn SD (119899 = 3)
China [24]This is because the nitrificationwas suppressed bylack of oxygen due to prolonged submergence The concen-tration of NH
4
+-N in surface water at tillering stage is higherthan that at the following three stages This is because thegrowth is strong at jointing-booting and panicle initiationstages which lead to the reduction of NH
4
+-N and NO3
minus-N
Generally nitrogen loss through drainage increases as Nrate and runoff volume increase especially as N rates aregreater than the economic optimum CID had been shownto decrease water flow [25] and thus supports results fromthis study Compared to CK the CID treatment significantlydecreases the loss of NH
4
+-N and NO3
minus-N indicating that
8 Journal of Chemistry
NH4
+-N and NO3
minus-N loads in the runoff were not only cor-related with runoff volume but also pertinent to NH
4
+-N andNO3
minus-N concentrations during given runoff eventsThis study only investigated the potential of CID at single
stage for reducing nitrogen emission from rice paddies inSouthern China It did not investigate the effect of CID at thecompound stages and the multistages and change of N aftersubmergence withdrawal More research needs to be carriedout in the future to define these relationships
5 Conclusions
In Southern China the water quality in paddy is easilyaffected by various forms ofNThe high rates of N applicationgenerally resulted in high concentrations of NH
4
+-N and TNin the surface water on the second day indicating the periodwith the highest risk of N runoff Compared to CK the con-centration of NO
3
minus-N in surface water showed some reduc-tion under CID at four stages but differed largely among thetreatments NH
4
+-Nwas themajor component of N in runoffwater after submergence at four stages Consistent with thereduction of drainage CID at four stages can significantlydecrease the amount of NO
3
minus-N and NH4
+-N losses byrunoff in relation to CK The study can be helpful for waterlevel management in rice paddy with compromise of watersaving reduction of N and high yield
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was funded by Key Program granted by theNational Nature amp Science Foundation of China (nos51479063 51279059 and 41271236) and supported by theSupporting Program of the ldquoOutstanding Young CreativeTalents in Hohai Universityrdquo ldquoOutstanding Scientific andTechnological Innovation Team in Jiangsu Colleges and Uni-versitiesrdquo and ldquothe Priority Academic Program Developmentof JiangsuHigher Education InstitutionsrdquoThe authors extendtheir gratitude to editor and the anonymous reviewers forsubstantial comments on earlier versions of this paper
References
[1] R W Skaggs D Amatya R O Evans and J E Parsons ldquoChar-acterization and evaluation of proposed hydrologic criteria forwetlandsrdquo Journal of Soil andWater Conservation vol 49 no 5pp 501ndash510 1994
[2] G W Randall and J A Vetsch ldquoNitrate losses in subsurfacedrainage from a corn-soybean rotation as affected by fall andspring application of nitrogen and nitrapyrinrdquo Journal of Envi-ronmental Quality vol 34 no 2 pp 590ndash597 2005
[3] N Chirinda J E Olesen J R Porter and P Schjoslashnning ldquoSoilproperties crop production and greenhouse gas emissions fromorganic and inorganic fertilizer-based arable cropping systemsrdquo
[4] K Wang R D Zhang and H Chen ldquoDrainage-process anal-yses for agricultural non-point-source pollution from irrigatedpaddy systemsrdquo Journal of Irrigation and Drainage Engineeringvol 140 Article ID 04013004 pp 1ndash14 2014
[5] P Belder B AM Bouman R Cabangon et al ldquoEffect of water-saving irrigation on rice yield and water use in typical lowlandconditions in AsiardquoAgriculturalWaterManagement vol 65 no3 pp 193ndash210 2004
[6] B A M Bouman ldquoA conceptual framework for the improve-ment of crop water productivity at different spatial scalesrdquoAgricultural Systems vol 93 no 1ndash3 pp 43ndash60 2007
[7] B A M Bouman E Humphreys T P Tuong and R BarkerldquoRice and waterrdquo Advances in Agronomy vol 92 pp 187ndash2372007
[8] G Shao J Cui S Yu et al ldquoImpacts of controlled irrigationand drainage on the yield and physiological attributes of riceImpacts of controlled irrigation and drainage on the yield andphysiological attributes of ricerdquo Agricultural Water Manage-ment vol 149 pp 156ndash165 2015
[9] K Surajit and D De Principles and Practices of Rice ProductionJohn Wiley amp Sons New York NY USA 1981
[10] C-G Lee T D Fletcher and G Sun ldquoNitrogen removal in con-structedwetland systemsrdquoEngineering in Life Sciences vol 9 no1 pp 11ndash22 2009
[11] Y Takai and T Kamura ldquoThe mechanism of reduction inwaterlogged paddy soilrdquo Folia Microbiologica vol 11 no 4 pp304ndash313 1966
[12] V Lalonde C A Madramootoo L Trenholm and R SBroughton ldquoEffects of controlled drainage onnitrate concentra-tions in subsurface drain dischargerdquo Agricultural Water Man-agement vol 29 no 2 pp 187ndash199 1996
[13] D Hesterberg B de Vos and P A C Raats ldquoChemistry ofsubsurface drain discharge from an agricultural polder soilrdquoAgricultural Water Management vol 86 no 1-2 pp 220ndash2282006
[14] M X Huang S Zhang Y J Tang and B X Chen ldquoNitrogenlosses from farm runoff under simulated rainfall conditionsrdquoSoil and Environmental Sciences vol 10 no 1 pp 6ndash10 2001
[15] IWesstrom and IMessing ldquoEffects of controlled drainage onNand P losses andNdynamics in a loamy sandwith spring cropsrdquoAgricultural Water Management vol 87 no 3 pp 229ndash2402007
[16] R O Evans R W Skaggs and J W Gilliam ldquoControlledversus conventional drainage effects on water qualityrdquo Journalof Irrigation and Drainage Engineering vol 121 no 4 pp 271ndash276 1995
[17] G W Randall and D J Mulla ldquoNitrate nitrogen in surfacewaters as influenced by climatic conditions and agriculturalpracticesrdquo Journal of Environmental Quality vol 30 no 2 pp337ndash344 2001
[18] Y-Q Zhang M-X Wen X-P Li and X-J Shi ldquoLong-termfertilisation causes excess supply and loss of phosphorus inpurple paddy soilrdquo Journal of the Science of Food andAgriculturevol 94 no 6 pp 1175ndash1183 2014
[19] X Guo J Yuan F Guo and Z Chen ldquoPreliminary study onwater-catching and controlled irrigation technology of ricerdquoTransactions of the Chinese Society of Agricultural Engineeringvol 25 no 4 pp 70ndash73 2009
Journal of Chemistry 9
[20] S E Yu Z M Miao W G Xing G C Shao and Y X JiangldquoResearch advance on irrigation and drainage for rice by usingfield water level as regulation indexrdquo Journal of Irrigation andDrainage vol 29 pp 134ndash136 2010 (Chinese)
[21] J E Ayars E W Christen and J W Hornbuckle ldquoControlleddrainage for improved water management in arid regionsirrigated agriculturerdquo Agricultural Water Management vol 86no 1-2 pp 128ndash139 2006
[22] N R Khatiwada andC Polprasert ldquoAssessment of effective spe-cific surface area for free water surface constructed wetlandsrdquoWater Science and Technology vol 40 no 3 pp 83ndash89 1999
[23] M Prosnansky Y Sakakibara and M Kuroda ldquoHigh-rate den-itrification and SS rejection by biofilm-electrode reactor (BER)combined with microfiltrationrdquoWater Research vol 36 no 19pp 4801ndash4810 2002
[24] X J Hu X H Shao Y Y Li J He S G Lu and Y Qiu ldquoEffectsof controlled and mid-gathering irrigation mode of paddy riceon the pollutants emission and reductionrdquo Energy Procedia vol16 pp 907ndash914 2012
[25] G-C Shao S Deng N Liu S-E Yu M-H Wang and D-LShe ldquoEffects of controlled irrigation and drainage on growthgrain yield and water use in paddy ricerdquo European Journal ofAgronomy vol 53 pp 1ndash9 2014
Figure 1 Schematic diagram of the experimental set-up placed in the tank
Table 1 Design of controlled irrigation and drainage (CID) scheduling
Treatments Tillering stage Jointing-booting stage Panicle initiation stage Milky stageT1 120mm (10 d) minus300mmsim30mm minus300mmsim30mm minus300mmsim30mmT2 minus200mmsim20mm 250mm (10 d) minus300mmsim30mm minus300mmsim30mmT3 minus200mmsim20mm minus300mmsim30mm 250mm (10 d) minus300mmsim30mmT4 minus200mmsim20mm minus300mmsim30mm minus300mmsim30mm 250mm (14 d)CK minus200mmsim20mm minus300mmsim30mm minus300mmsim30mm minus300mmsim30mmNote minus119868mmsim119869mm denotes that water depth was kept between ndash119868mm and 119869mm at four stages of paddy rice at normal time when water level lowered tominus119868mm irrigation water is added until water table reached 119869mm 119870mm (119867d) indicates that 119870mm fixed water level was kept with duration of 119867 days atfour stages of paddy rice from the soil surface The allowable variation of fixed water level was plusmn5mm during the period of implementation The maximumwater height after rainfall for the control is 50mm at the tillering stage and 100mm at other stages When rainfall increased water depth beyond the designedvalue drainage occurs 4mm water leakage per day was kept when water table existed at soil surface AWD indicates alternate wetting and drying irrigationCID-Stage I CID-Stage II CID-Stage III and CID-Stage IV denote the CID treatments at tillering stage (Stage I) jointing-booting stage (Stage II) panicleinitiation stage (Stage III) and milky stage (Stage IV) respectively
24 Sample Collection and Measurement Field water depthwas observed at 9 orsquoclock by ruler When the minimum levelwas reached the autoirrigation system would irrigate untilwater level reached maximum level Similarly when waterlevel exceeded maximum level due to rainfall the drainagevolume was subsequently calculated by counting the numberof solenoid valves opened and stored by a datalogger Watersamples were collected in the polyethylene bottle for fourtimes during the submergence period The surface water wascollected by the 50mL syringe (without disturbing the soiland selecting the top surfacewater randomly) rinse all bottlesfirstly and then take the appropriate amount of water sampleThe subsurface water was collected by the undergrounddrainage pipe The water samples were analyzed for ammo-nium nitrogen (NH
4
+-N) and nitrate nitrogen (NO3
minus-N) byusing a Shimadzu UV-2800 spectrophotometer In accor-dance with ldquowater and wastewater monitoring and analysismethodsrdquo alkaline per sulfate digestion and Nesslerrsquos reagentcolorimetric phenol disulfonic acid spectrophotometer wereused to analyze total nitrogen in water test (TN) ammonia(NH4
+-N) andnitrate (NO3
minus-N) contentTheN loss throughrunoffwas calculated as the product of NH
4
+-N andNO3
minus-Nconcentration in runoff and the amount of runoff
25 Statistical Analysis We used a randomized completeblock design with three replications Treatment effects wereanalyzed using analysis of variance (ANOVA) procedure ofSPSS software version 140 Treatment means were separatedby least significant difference (LSD) test at 119875 le 005 unlessotherwise specified
3 Results
31 The Change of the Concentration of NH4+-N NO3
minus-Nand TN after Fertilization Concentrations of NH
4
+-N andNO3
minus-N andTN in surfacewater and groundwaterweremea-sured after fertilization application from tillering to jointing-booting stage in 2009 and 2010 (Figure 2 and Table 2) Afterfertilization application at tillering stage the highest con-centration of NH
4
+-N in surface water was obtained on thesecond day while for NO
3
minus-N the highest concentration wasobserved on the third day (Figures 2(a)ndash2(d)) The averageconcentration of NH
4
+-N and NO3
minus-N in the surface waterof paddy decreased dramatically after 7 days of submergenceGenerally the high rates of N application generally resultedin high concentrations of TN in the surface water especially
4 Journal of Chemistry
0
10
20
30
40
50
SurfaceUnderground
630 736282009
627
NH
4
+-N
(mgmiddot
Lminus1)
(a)
79762010
71275
SurfaceUnderground
0
10
20
30
40
50
NH
4
+-N
(mgmiddot
Lminus1)
(b)
SurfaceUnderground
0
03
06
09
12
15
18
627 630 736282009
NO
3
minus-N
(mgmiddot
Lminus1)
(c)
79 71276752010
SurfaceUnderground
0
03
06
09
12
15
18N
O3
minus-N
(mgmiddot
Lminus1)
(d)
0
20
40
60
627 630 736282009
SurfaceUnderground
TN (m
gmiddotLminus
1)
(e)
79 71276752010
SurfaceUnderground
0
20
40
60
TN (m
gmiddotLminus
1)
(f)
Figure 2 The change of the concentration of NH4
+-N NO3
minus-N and TN after fertilization at tillering stage in 2009 and 2010
Journal of Chemistry 5
Table 2The change of the concentration of NH4
+-N NO3
minus-N andTN after fertilization at tillering stage in 2010
within 7 days after N application which showed the increas-ing potential of N loss by runoff (Figures 2(e)-2(f)) Theconcentration of NH
4
+-N and TN in underground watershowed more stability than those in surface water afterfertilizer applicationThe concentration ofNO
3
minus-N in under-ground water reached the maximum on the second day andthen declinewith time passing During the period of jointing-booting the highest concentrations of NH
4
+-N and NO3
minus-Nin surface water were observed on the third day after applyingfertilization while for TN the highest concentration wasobtained on the fifth day (Table 2) The difference betweentillering and jointing-booting stages may be attributed todifferent absorption during crop growth and environmentalfactors The change of concentration of NH
4
+-N and NO3
minus-N in underground water demonstrated similar trend to theconcentration of TN in surface water The concentration ofTN within 7 days after N application was not significantlydifferent
32 The Change of Concentration of NH4+-N during Submer-
gence The concentration of NH4
+-N under CK increasedwith the time of submergence and reaches the maximum atthe tenth day at tillering stage (Figure 3(a))The average con-centration of NH
4
+-N under T1 was 400 higher than thatunder CK on the first day after submergence The differencesin the concentration of NH
4
+-N between T1 and CK weresignificant at four timesrsquo measurements As is shown inFigure 3(b) the concentration of NH
4
+-N under CK and T2demonstrated the decline trend with time going on This isbecause the crop absorbed some NH
4
+-N during submer-gence and resulted in the gradual decline of the concentrationof NH
4
+-N There were not significant differences in theconcentration ofNH
4
+-NbetweenT2 andCKThedynamiticchanges of the concentration of NH
4
+-N at panicle initiationstage during submergence were showed in Figure 3(c) Theconcentration of NH
4
+-N under T3 and CK reached themaximum after 3-day submergence and then decreased astime goes on T3 significantly increased the concentration ofNH4
+-N during the submergence compared to CK Duringthe submergence at milky stage the concentrations of NH
4
+-N under CK and T4 showed a trend of rise first and thenfall (Figure 3(d)) Compared with CK submergence at milkystage also significantly increased the concentration of NH
4
+-N
33 The Change of Concentration of NO3minus-N during Sub-
mergence The dynamitic changes of NO3
minus-N in surfacewater after submergence at four stages in 2010 were shownin Figure 4 Submergence at tillering stage increased theconcentration of NO
3
minus-N but the difference between T1 andCK was not significant (Figure 4(a)) The concentration ofNO3
minus-N for T1 declined with prolonged submergence Theconcentration ofNO
3
minus-NunderT1 at the end of submergencedecreased to 38 of that on the first day The concentrationsof NO
3
minus-N at jointing-booting stage were averagely lowerthan that at tillering stage It is because rice grew rapidly atjointing-booting stage and absorbed more nitrogen resultingin the reduction in the concentration of NO
3
minus-N Submer-gence at jointing-booting stage significantly reduced the con-centration of NO
3
minus-N (Figure 4(b)) As shown in Figure 4(c)NO3
minus-N concentrations under the treatment T3 were lowerthan those under CK treatment during the submergenceexcept at the eighth day The concentration of NO
3
minus-N wasnot significantly decreased by submergence compared to CKAt milky stage it was observed that the concentration ofNO3
minus-N under T4 showed the trend of rise after first declineThis may be attributed to the decomposition of leaves sub-merged in water at milky stage The differences in the con-centration of NO
3
minus-N between T4 and CK were significant(Figure 4(d))
34 Potential of NH4+-N and NO3
minus-N Loss by Runoff duringSubmergence NH
4
+-N and NO3
minus-N losses by runoff indifferent treatments as influenced by submergence at differentstages during the year of 2010 were presented in Table 3 Aswas the case with surface water NH
4
+-N was the major com-ponent ofN in runoffwater RegardingNH
4
+-N andNO3
minus-Nloss by runoff at tillering stage the amount was decreased by76 and 83 by submergence (T1) as compared with the CKtreatment respectively The NH
4
+-N loss under T2 T3 andT4 was only 24 53 and 12 respectively of that underCK CID at jointing-booting panicle initiation and milkystages also decreases the amount of NO
3
minus-N loss by 91 91and 85 in relation to CK
4 Discussion
The increased attention being paid to the loss of nitrate viaagricultural drainage has led many to call for significantchanges in both management of N fertilizer and manage-ment of agricultural drainage systems [17] Overall currentagronomic guidelines which are primarily based on cropresponse may inadequately protect the water quality inSouthern China [18] Although positive results were obtainedby applying AWD technology in rice fields the drainagevolume in AWD has been reported to be larger due to theexcessive drainage requirement which results in an increasein nitrate losses from the agricultural fields [19 20] This canbe partially addressed by the introduction of irrigation anddrainage management This then allows drainage design andmanagement within the reasonable bounds expected forlong-term nitrate control [21]
6 Journal of Chemistry
00
10
20
30
40
50
CKT1
722 725 728719
NH
4
+-N
(mgmiddot
Lminus1)
(a)
814 817 820
CKT2
00
10
20
30
40
50
NH
4
+-N
(mgmiddot
Lminus1)
823
(b)
00
10
20
30
40
50
830 92 95 98
CKT3
NH
4
+-N
(mgmiddot
Lminus1)
(c)
CKT4
912 915 918 92100
10
20
30
40
50N
H4
+-N
(mgmiddot
Lminus1)
(d)
Figure 3 The change of the concentration of NH4
+-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
The various forms of N caused by the actions of microor-ganisms are dependent on temperature and time The sub-sequent movement of nitrate is dependent on the presenceof water in excess of field capacity This timing should corre-spond with the plantrsquos need for N Logically placement of Ninto the soil profile as a fertilizer addition would ideally be asclose to the time that a plant needs the nutrient as possibleto minimize the chance for loss into the environment In thisexperiment we observed that urea fertilization can signifi-cantly increase the concentration of NH
4
+-N and TN but hasa little influence on NO
3
minus-NThe major nitrogen treatment mechanisms of rice paddy
include microbial interactions with nitrogen sedimentation
chemical adsorption and plant uptake [22] In tradi-tional nitrogen treatments the biological nitrogen transitionrequires a two-step process nitrification followed by denitri-fication Nitrification implies a chemolithoautotrophic oxida-tion of ammonia to nitrate under strict aerobic conditionsThe nitrification process is very oxygen demanding Duringthe submergence the biological denitrification mechanismmakes use of nitrate as the terminal electron acceptor inlow-oxygen environments [23] Under CID condition theconcentrations of NH
4
+-N at four stages were higher thanthat of NO
3
minus-N As is shown in Table 3 NH4
+-N was themajor component of N in runoff water after submergenceSimilar results were also reported in paddy soil in Southern
Journal of Chemistry 7
00
03
06
09
12
15
CKT1
719 725 728722
NO
3
minus-N
(mgmiddot
Lminus1)
(a)
823
CKT2
82081781400
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(b)
00
03
06
09
12
15
9592830 98
CKT3
NO
3
minus-N
(mgmiddot
Lminus1)
(c)
918915912 921
CKT4
00
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(d)
Figure 4The change of the concentration of NO3
minus-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
Table 3 Nitrogen loss by runoff during the period of submergence in 2010
Form of N Tillering stage Jointing-booting stage Panicle initiation stage Milky stageT1 CK T2 CK T3 CK T4 CK
minus-N (gha) 36 plusmn 21 214 plusmn 102 42 plusmn 53 485 plusmn 198 84 plusmn 48 910 plusmn 438 30 plusmn 18 196 plusmn 93Note CK indicates alternate drying and wet irrigation T1 T2 T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiationstage and milky stage respectively Each value is the mean plusmn SD (119899 = 3)
China [24]This is because the nitrificationwas suppressed bylack of oxygen due to prolonged submergence The concen-tration of NH
4
+-N in surface water at tillering stage is higherthan that at the following three stages This is because thegrowth is strong at jointing-booting and panicle initiationstages which lead to the reduction of NH
4
+-N and NO3
minus-N
Generally nitrogen loss through drainage increases as Nrate and runoff volume increase especially as N rates aregreater than the economic optimum CID had been shownto decrease water flow [25] and thus supports results fromthis study Compared to CK the CID treatment significantlydecreases the loss of NH
4
+-N and NO3
minus-N indicating that
8 Journal of Chemistry
NH4
+-N and NO3
minus-N loads in the runoff were not only cor-related with runoff volume but also pertinent to NH
4
+-N andNO3
minus-N concentrations during given runoff eventsThis study only investigated the potential of CID at single
stage for reducing nitrogen emission from rice paddies inSouthern China It did not investigate the effect of CID at thecompound stages and the multistages and change of N aftersubmergence withdrawal More research needs to be carriedout in the future to define these relationships
5 Conclusions
In Southern China the water quality in paddy is easilyaffected by various forms ofNThe high rates of N applicationgenerally resulted in high concentrations of NH
4
+-N and TNin the surface water on the second day indicating the periodwith the highest risk of N runoff Compared to CK the con-centration of NO
3
minus-N in surface water showed some reduc-tion under CID at four stages but differed largely among thetreatments NH
4
+-Nwas themajor component of N in runoffwater after submergence at four stages Consistent with thereduction of drainage CID at four stages can significantlydecrease the amount of NO
3
minus-N and NH4
+-N losses byrunoff in relation to CK The study can be helpful for waterlevel management in rice paddy with compromise of watersaving reduction of N and high yield
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was funded by Key Program granted by theNational Nature amp Science Foundation of China (nos51479063 51279059 and 41271236) and supported by theSupporting Program of the ldquoOutstanding Young CreativeTalents in Hohai Universityrdquo ldquoOutstanding Scientific andTechnological Innovation Team in Jiangsu Colleges and Uni-versitiesrdquo and ldquothe Priority Academic Program Developmentof JiangsuHigher Education InstitutionsrdquoThe authors extendtheir gratitude to editor and the anonymous reviewers forsubstantial comments on earlier versions of this paper
References
[1] R W Skaggs D Amatya R O Evans and J E Parsons ldquoChar-acterization and evaluation of proposed hydrologic criteria forwetlandsrdquo Journal of Soil andWater Conservation vol 49 no 5pp 501ndash510 1994
[2] G W Randall and J A Vetsch ldquoNitrate losses in subsurfacedrainage from a corn-soybean rotation as affected by fall andspring application of nitrogen and nitrapyrinrdquo Journal of Envi-ronmental Quality vol 34 no 2 pp 590ndash597 2005
[3] N Chirinda J E Olesen J R Porter and P Schjoslashnning ldquoSoilproperties crop production and greenhouse gas emissions fromorganic and inorganic fertilizer-based arable cropping systemsrdquo
[4] K Wang R D Zhang and H Chen ldquoDrainage-process anal-yses for agricultural non-point-source pollution from irrigatedpaddy systemsrdquo Journal of Irrigation and Drainage Engineeringvol 140 Article ID 04013004 pp 1ndash14 2014
[5] P Belder B AM Bouman R Cabangon et al ldquoEffect of water-saving irrigation on rice yield and water use in typical lowlandconditions in AsiardquoAgriculturalWaterManagement vol 65 no3 pp 193ndash210 2004
[6] B A M Bouman ldquoA conceptual framework for the improve-ment of crop water productivity at different spatial scalesrdquoAgricultural Systems vol 93 no 1ndash3 pp 43ndash60 2007
[7] B A M Bouman E Humphreys T P Tuong and R BarkerldquoRice and waterrdquo Advances in Agronomy vol 92 pp 187ndash2372007
[8] G Shao J Cui S Yu et al ldquoImpacts of controlled irrigationand drainage on the yield and physiological attributes of riceImpacts of controlled irrigation and drainage on the yield andphysiological attributes of ricerdquo Agricultural Water Manage-ment vol 149 pp 156ndash165 2015
[9] K Surajit and D De Principles and Practices of Rice ProductionJohn Wiley amp Sons New York NY USA 1981
[10] C-G Lee T D Fletcher and G Sun ldquoNitrogen removal in con-structedwetland systemsrdquoEngineering in Life Sciences vol 9 no1 pp 11ndash22 2009
[11] Y Takai and T Kamura ldquoThe mechanism of reduction inwaterlogged paddy soilrdquo Folia Microbiologica vol 11 no 4 pp304ndash313 1966
[12] V Lalonde C A Madramootoo L Trenholm and R SBroughton ldquoEffects of controlled drainage onnitrate concentra-tions in subsurface drain dischargerdquo Agricultural Water Man-agement vol 29 no 2 pp 187ndash199 1996
[13] D Hesterberg B de Vos and P A C Raats ldquoChemistry ofsubsurface drain discharge from an agricultural polder soilrdquoAgricultural Water Management vol 86 no 1-2 pp 220ndash2282006
[14] M X Huang S Zhang Y J Tang and B X Chen ldquoNitrogenlosses from farm runoff under simulated rainfall conditionsrdquoSoil and Environmental Sciences vol 10 no 1 pp 6ndash10 2001
[15] IWesstrom and IMessing ldquoEffects of controlled drainage onNand P losses andNdynamics in a loamy sandwith spring cropsrdquoAgricultural Water Management vol 87 no 3 pp 229ndash2402007
[16] R O Evans R W Skaggs and J W Gilliam ldquoControlledversus conventional drainage effects on water qualityrdquo Journalof Irrigation and Drainage Engineering vol 121 no 4 pp 271ndash276 1995
[17] G W Randall and D J Mulla ldquoNitrate nitrogen in surfacewaters as influenced by climatic conditions and agriculturalpracticesrdquo Journal of Environmental Quality vol 30 no 2 pp337ndash344 2001
[18] Y-Q Zhang M-X Wen X-P Li and X-J Shi ldquoLong-termfertilisation causes excess supply and loss of phosphorus inpurple paddy soilrdquo Journal of the Science of Food andAgriculturevol 94 no 6 pp 1175ndash1183 2014
[19] X Guo J Yuan F Guo and Z Chen ldquoPreliminary study onwater-catching and controlled irrigation technology of ricerdquoTransactions of the Chinese Society of Agricultural Engineeringvol 25 no 4 pp 70ndash73 2009
Journal of Chemistry 9
[20] S E Yu Z M Miao W G Xing G C Shao and Y X JiangldquoResearch advance on irrigation and drainage for rice by usingfield water level as regulation indexrdquo Journal of Irrigation andDrainage vol 29 pp 134ndash136 2010 (Chinese)
[21] J E Ayars E W Christen and J W Hornbuckle ldquoControlleddrainage for improved water management in arid regionsirrigated agriculturerdquo Agricultural Water Management vol 86no 1-2 pp 128ndash139 2006
[22] N R Khatiwada andC Polprasert ldquoAssessment of effective spe-cific surface area for free water surface constructed wetlandsrdquoWater Science and Technology vol 40 no 3 pp 83ndash89 1999
[23] M Prosnansky Y Sakakibara and M Kuroda ldquoHigh-rate den-itrification and SS rejection by biofilm-electrode reactor (BER)combined with microfiltrationrdquoWater Research vol 36 no 19pp 4801ndash4810 2002
[24] X J Hu X H Shao Y Y Li J He S G Lu and Y Qiu ldquoEffectsof controlled and mid-gathering irrigation mode of paddy riceon the pollutants emission and reductionrdquo Energy Procedia vol16 pp 907ndash914 2012
[25] G-C Shao S Deng N Liu S-E Yu M-H Wang and D-LShe ldquoEffects of controlled irrigation and drainage on growthgrain yield and water use in paddy ricerdquo European Journal ofAgronomy vol 53 pp 1ndash9 2014
within 7 days after N application which showed the increas-ing potential of N loss by runoff (Figures 2(e)-2(f)) Theconcentration of NH
4
+-N and TN in underground watershowed more stability than those in surface water afterfertilizer applicationThe concentration ofNO
3
minus-N in under-ground water reached the maximum on the second day andthen declinewith time passing During the period of jointing-booting the highest concentrations of NH
4
+-N and NO3
minus-Nin surface water were observed on the third day after applyingfertilization while for TN the highest concentration wasobtained on the fifth day (Table 2) The difference betweentillering and jointing-booting stages may be attributed todifferent absorption during crop growth and environmentalfactors The change of concentration of NH
4
+-N and NO3
minus-N in underground water demonstrated similar trend to theconcentration of TN in surface water The concentration ofTN within 7 days after N application was not significantlydifferent
32 The Change of Concentration of NH4+-N during Submer-
gence The concentration of NH4
+-N under CK increasedwith the time of submergence and reaches the maximum atthe tenth day at tillering stage (Figure 3(a))The average con-centration of NH
4
+-N under T1 was 400 higher than thatunder CK on the first day after submergence The differencesin the concentration of NH
4
+-N between T1 and CK weresignificant at four timesrsquo measurements As is shown inFigure 3(b) the concentration of NH
4
+-N under CK and T2demonstrated the decline trend with time going on This isbecause the crop absorbed some NH
4
+-N during submer-gence and resulted in the gradual decline of the concentrationof NH
4
+-N There were not significant differences in theconcentration ofNH
4
+-NbetweenT2 andCKThedynamiticchanges of the concentration of NH
4
+-N at panicle initiationstage during submergence were showed in Figure 3(c) Theconcentration of NH
4
+-N under T3 and CK reached themaximum after 3-day submergence and then decreased astime goes on T3 significantly increased the concentration ofNH4
+-N during the submergence compared to CK Duringthe submergence at milky stage the concentrations of NH
4
+-N under CK and T4 showed a trend of rise first and thenfall (Figure 3(d)) Compared with CK submergence at milkystage also significantly increased the concentration of NH
4
+-N
33 The Change of Concentration of NO3minus-N during Sub-
mergence The dynamitic changes of NO3
minus-N in surfacewater after submergence at four stages in 2010 were shownin Figure 4 Submergence at tillering stage increased theconcentration of NO
3
minus-N but the difference between T1 andCK was not significant (Figure 4(a)) The concentration ofNO3
minus-N for T1 declined with prolonged submergence Theconcentration ofNO
3
minus-NunderT1 at the end of submergencedecreased to 38 of that on the first day The concentrationsof NO
3
minus-N at jointing-booting stage were averagely lowerthan that at tillering stage It is because rice grew rapidly atjointing-booting stage and absorbed more nitrogen resultingin the reduction in the concentration of NO
3
minus-N Submer-gence at jointing-booting stage significantly reduced the con-centration of NO
3
minus-N (Figure 4(b)) As shown in Figure 4(c)NO3
minus-N concentrations under the treatment T3 were lowerthan those under CK treatment during the submergenceexcept at the eighth day The concentration of NO
3
minus-N wasnot significantly decreased by submergence compared to CKAt milky stage it was observed that the concentration ofNO3
minus-N under T4 showed the trend of rise after first declineThis may be attributed to the decomposition of leaves sub-merged in water at milky stage The differences in the con-centration of NO
3
minus-N between T4 and CK were significant(Figure 4(d))
34 Potential of NH4+-N and NO3
minus-N Loss by Runoff duringSubmergence NH
4
+-N and NO3
minus-N losses by runoff indifferent treatments as influenced by submergence at differentstages during the year of 2010 were presented in Table 3 Aswas the case with surface water NH
4
+-N was the major com-ponent ofN in runoffwater RegardingNH
4
+-N andNO3
minus-Nloss by runoff at tillering stage the amount was decreased by76 and 83 by submergence (T1) as compared with the CKtreatment respectively The NH
4
+-N loss under T2 T3 andT4 was only 24 53 and 12 respectively of that underCK CID at jointing-booting panicle initiation and milkystages also decreases the amount of NO
3
minus-N loss by 91 91and 85 in relation to CK
4 Discussion
The increased attention being paid to the loss of nitrate viaagricultural drainage has led many to call for significantchanges in both management of N fertilizer and manage-ment of agricultural drainage systems [17] Overall currentagronomic guidelines which are primarily based on cropresponse may inadequately protect the water quality inSouthern China [18] Although positive results were obtainedby applying AWD technology in rice fields the drainagevolume in AWD has been reported to be larger due to theexcessive drainage requirement which results in an increasein nitrate losses from the agricultural fields [19 20] This canbe partially addressed by the introduction of irrigation anddrainage management This then allows drainage design andmanagement within the reasonable bounds expected forlong-term nitrate control [21]
6 Journal of Chemistry
00
10
20
30
40
50
CKT1
722 725 728719
NH
4
+-N
(mgmiddot
Lminus1)
(a)
814 817 820
CKT2
00
10
20
30
40
50
NH
4
+-N
(mgmiddot
Lminus1)
823
(b)
00
10
20
30
40
50
830 92 95 98
CKT3
NH
4
+-N
(mgmiddot
Lminus1)
(c)
CKT4
912 915 918 92100
10
20
30
40
50N
H4
+-N
(mgmiddot
Lminus1)
(d)
Figure 3 The change of the concentration of NH4
+-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
The various forms of N caused by the actions of microor-ganisms are dependent on temperature and time The sub-sequent movement of nitrate is dependent on the presenceof water in excess of field capacity This timing should corre-spond with the plantrsquos need for N Logically placement of Ninto the soil profile as a fertilizer addition would ideally be asclose to the time that a plant needs the nutrient as possibleto minimize the chance for loss into the environment In thisexperiment we observed that urea fertilization can signifi-cantly increase the concentration of NH
4
+-N and TN but hasa little influence on NO
3
minus-NThe major nitrogen treatment mechanisms of rice paddy
include microbial interactions with nitrogen sedimentation
chemical adsorption and plant uptake [22] In tradi-tional nitrogen treatments the biological nitrogen transitionrequires a two-step process nitrification followed by denitri-fication Nitrification implies a chemolithoautotrophic oxida-tion of ammonia to nitrate under strict aerobic conditionsThe nitrification process is very oxygen demanding Duringthe submergence the biological denitrification mechanismmakes use of nitrate as the terminal electron acceptor inlow-oxygen environments [23] Under CID condition theconcentrations of NH
4
+-N at four stages were higher thanthat of NO
3
minus-N As is shown in Table 3 NH4
+-N was themajor component of N in runoff water after submergenceSimilar results were also reported in paddy soil in Southern
Journal of Chemistry 7
00
03
06
09
12
15
CKT1
719 725 728722
NO
3
minus-N
(mgmiddot
Lminus1)
(a)
823
CKT2
82081781400
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(b)
00
03
06
09
12
15
9592830 98
CKT3
NO
3
minus-N
(mgmiddot
Lminus1)
(c)
918915912 921
CKT4
00
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(d)
Figure 4The change of the concentration of NO3
minus-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
Table 3 Nitrogen loss by runoff during the period of submergence in 2010
Form of N Tillering stage Jointing-booting stage Panicle initiation stage Milky stageT1 CK T2 CK T3 CK T4 CK
minus-N (gha) 36 plusmn 21 214 plusmn 102 42 plusmn 53 485 plusmn 198 84 plusmn 48 910 plusmn 438 30 plusmn 18 196 plusmn 93Note CK indicates alternate drying and wet irrigation T1 T2 T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiationstage and milky stage respectively Each value is the mean plusmn SD (119899 = 3)
China [24]This is because the nitrificationwas suppressed bylack of oxygen due to prolonged submergence The concen-tration of NH
4
+-N in surface water at tillering stage is higherthan that at the following three stages This is because thegrowth is strong at jointing-booting and panicle initiationstages which lead to the reduction of NH
4
+-N and NO3
minus-N
Generally nitrogen loss through drainage increases as Nrate and runoff volume increase especially as N rates aregreater than the economic optimum CID had been shownto decrease water flow [25] and thus supports results fromthis study Compared to CK the CID treatment significantlydecreases the loss of NH
4
+-N and NO3
minus-N indicating that
8 Journal of Chemistry
NH4
+-N and NO3
minus-N loads in the runoff were not only cor-related with runoff volume but also pertinent to NH
4
+-N andNO3
minus-N concentrations during given runoff eventsThis study only investigated the potential of CID at single
stage for reducing nitrogen emission from rice paddies inSouthern China It did not investigate the effect of CID at thecompound stages and the multistages and change of N aftersubmergence withdrawal More research needs to be carriedout in the future to define these relationships
5 Conclusions
In Southern China the water quality in paddy is easilyaffected by various forms ofNThe high rates of N applicationgenerally resulted in high concentrations of NH
4
+-N and TNin the surface water on the second day indicating the periodwith the highest risk of N runoff Compared to CK the con-centration of NO
3
minus-N in surface water showed some reduc-tion under CID at four stages but differed largely among thetreatments NH
4
+-Nwas themajor component of N in runoffwater after submergence at four stages Consistent with thereduction of drainage CID at four stages can significantlydecrease the amount of NO
3
minus-N and NH4
+-N losses byrunoff in relation to CK The study can be helpful for waterlevel management in rice paddy with compromise of watersaving reduction of N and high yield
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was funded by Key Program granted by theNational Nature amp Science Foundation of China (nos51479063 51279059 and 41271236) and supported by theSupporting Program of the ldquoOutstanding Young CreativeTalents in Hohai Universityrdquo ldquoOutstanding Scientific andTechnological Innovation Team in Jiangsu Colleges and Uni-versitiesrdquo and ldquothe Priority Academic Program Developmentof JiangsuHigher Education InstitutionsrdquoThe authors extendtheir gratitude to editor and the anonymous reviewers forsubstantial comments on earlier versions of this paper
References
[1] R W Skaggs D Amatya R O Evans and J E Parsons ldquoChar-acterization and evaluation of proposed hydrologic criteria forwetlandsrdquo Journal of Soil andWater Conservation vol 49 no 5pp 501ndash510 1994
[2] G W Randall and J A Vetsch ldquoNitrate losses in subsurfacedrainage from a corn-soybean rotation as affected by fall andspring application of nitrogen and nitrapyrinrdquo Journal of Envi-ronmental Quality vol 34 no 2 pp 590ndash597 2005
[3] N Chirinda J E Olesen J R Porter and P Schjoslashnning ldquoSoilproperties crop production and greenhouse gas emissions fromorganic and inorganic fertilizer-based arable cropping systemsrdquo
[4] K Wang R D Zhang and H Chen ldquoDrainage-process anal-yses for agricultural non-point-source pollution from irrigatedpaddy systemsrdquo Journal of Irrigation and Drainage Engineeringvol 140 Article ID 04013004 pp 1ndash14 2014
[5] P Belder B AM Bouman R Cabangon et al ldquoEffect of water-saving irrigation on rice yield and water use in typical lowlandconditions in AsiardquoAgriculturalWaterManagement vol 65 no3 pp 193ndash210 2004
[6] B A M Bouman ldquoA conceptual framework for the improve-ment of crop water productivity at different spatial scalesrdquoAgricultural Systems vol 93 no 1ndash3 pp 43ndash60 2007
[7] B A M Bouman E Humphreys T P Tuong and R BarkerldquoRice and waterrdquo Advances in Agronomy vol 92 pp 187ndash2372007
[8] G Shao J Cui S Yu et al ldquoImpacts of controlled irrigationand drainage on the yield and physiological attributes of riceImpacts of controlled irrigation and drainage on the yield andphysiological attributes of ricerdquo Agricultural Water Manage-ment vol 149 pp 156ndash165 2015
[9] K Surajit and D De Principles and Practices of Rice ProductionJohn Wiley amp Sons New York NY USA 1981
[10] C-G Lee T D Fletcher and G Sun ldquoNitrogen removal in con-structedwetland systemsrdquoEngineering in Life Sciences vol 9 no1 pp 11ndash22 2009
[11] Y Takai and T Kamura ldquoThe mechanism of reduction inwaterlogged paddy soilrdquo Folia Microbiologica vol 11 no 4 pp304ndash313 1966
[12] V Lalonde C A Madramootoo L Trenholm and R SBroughton ldquoEffects of controlled drainage onnitrate concentra-tions in subsurface drain dischargerdquo Agricultural Water Man-agement vol 29 no 2 pp 187ndash199 1996
[13] D Hesterberg B de Vos and P A C Raats ldquoChemistry ofsubsurface drain discharge from an agricultural polder soilrdquoAgricultural Water Management vol 86 no 1-2 pp 220ndash2282006
[14] M X Huang S Zhang Y J Tang and B X Chen ldquoNitrogenlosses from farm runoff under simulated rainfall conditionsrdquoSoil and Environmental Sciences vol 10 no 1 pp 6ndash10 2001
[15] IWesstrom and IMessing ldquoEffects of controlled drainage onNand P losses andNdynamics in a loamy sandwith spring cropsrdquoAgricultural Water Management vol 87 no 3 pp 229ndash2402007
[16] R O Evans R W Skaggs and J W Gilliam ldquoControlledversus conventional drainage effects on water qualityrdquo Journalof Irrigation and Drainage Engineering vol 121 no 4 pp 271ndash276 1995
[17] G W Randall and D J Mulla ldquoNitrate nitrogen in surfacewaters as influenced by climatic conditions and agriculturalpracticesrdquo Journal of Environmental Quality vol 30 no 2 pp337ndash344 2001
[18] Y-Q Zhang M-X Wen X-P Li and X-J Shi ldquoLong-termfertilisation causes excess supply and loss of phosphorus inpurple paddy soilrdquo Journal of the Science of Food andAgriculturevol 94 no 6 pp 1175ndash1183 2014
[19] X Guo J Yuan F Guo and Z Chen ldquoPreliminary study onwater-catching and controlled irrigation technology of ricerdquoTransactions of the Chinese Society of Agricultural Engineeringvol 25 no 4 pp 70ndash73 2009
Journal of Chemistry 9
[20] S E Yu Z M Miao W G Xing G C Shao and Y X JiangldquoResearch advance on irrigation and drainage for rice by usingfield water level as regulation indexrdquo Journal of Irrigation andDrainage vol 29 pp 134ndash136 2010 (Chinese)
[21] J E Ayars E W Christen and J W Hornbuckle ldquoControlleddrainage for improved water management in arid regionsirrigated agriculturerdquo Agricultural Water Management vol 86no 1-2 pp 128ndash139 2006
[22] N R Khatiwada andC Polprasert ldquoAssessment of effective spe-cific surface area for free water surface constructed wetlandsrdquoWater Science and Technology vol 40 no 3 pp 83ndash89 1999
[23] M Prosnansky Y Sakakibara and M Kuroda ldquoHigh-rate den-itrification and SS rejection by biofilm-electrode reactor (BER)combined with microfiltrationrdquoWater Research vol 36 no 19pp 4801ndash4810 2002
[24] X J Hu X H Shao Y Y Li J He S G Lu and Y Qiu ldquoEffectsof controlled and mid-gathering irrigation mode of paddy riceon the pollutants emission and reductionrdquo Energy Procedia vol16 pp 907ndash914 2012
[25] G-C Shao S Deng N Liu S-E Yu M-H Wang and D-LShe ldquoEffects of controlled irrigation and drainage on growthgrain yield and water use in paddy ricerdquo European Journal ofAgronomy vol 53 pp 1ndash9 2014
within 7 days after N application which showed the increas-ing potential of N loss by runoff (Figures 2(e)-2(f)) Theconcentration of NH
4
+-N and TN in underground watershowed more stability than those in surface water afterfertilizer applicationThe concentration ofNO
3
minus-N in under-ground water reached the maximum on the second day andthen declinewith time passing During the period of jointing-booting the highest concentrations of NH
4
+-N and NO3
minus-Nin surface water were observed on the third day after applyingfertilization while for TN the highest concentration wasobtained on the fifth day (Table 2) The difference betweentillering and jointing-booting stages may be attributed todifferent absorption during crop growth and environmentalfactors The change of concentration of NH
4
+-N and NO3
minus-N in underground water demonstrated similar trend to theconcentration of TN in surface water The concentration ofTN within 7 days after N application was not significantlydifferent
32 The Change of Concentration of NH4+-N during Submer-
gence The concentration of NH4
+-N under CK increasedwith the time of submergence and reaches the maximum atthe tenth day at tillering stage (Figure 3(a))The average con-centration of NH
4
+-N under T1 was 400 higher than thatunder CK on the first day after submergence The differencesin the concentration of NH
4
+-N between T1 and CK weresignificant at four timesrsquo measurements As is shown inFigure 3(b) the concentration of NH
4
+-N under CK and T2demonstrated the decline trend with time going on This isbecause the crop absorbed some NH
4
+-N during submer-gence and resulted in the gradual decline of the concentrationof NH
4
+-N There were not significant differences in theconcentration ofNH
4
+-NbetweenT2 andCKThedynamiticchanges of the concentration of NH
4
+-N at panicle initiationstage during submergence were showed in Figure 3(c) Theconcentration of NH
4
+-N under T3 and CK reached themaximum after 3-day submergence and then decreased astime goes on T3 significantly increased the concentration ofNH4
+-N during the submergence compared to CK Duringthe submergence at milky stage the concentrations of NH
4
+-N under CK and T4 showed a trend of rise first and thenfall (Figure 3(d)) Compared with CK submergence at milkystage also significantly increased the concentration of NH
4
+-N
33 The Change of Concentration of NO3minus-N during Sub-
mergence The dynamitic changes of NO3
minus-N in surfacewater after submergence at four stages in 2010 were shownin Figure 4 Submergence at tillering stage increased theconcentration of NO
3
minus-N but the difference between T1 andCK was not significant (Figure 4(a)) The concentration ofNO3
minus-N for T1 declined with prolonged submergence Theconcentration ofNO
3
minus-NunderT1 at the end of submergencedecreased to 38 of that on the first day The concentrationsof NO
3
minus-N at jointing-booting stage were averagely lowerthan that at tillering stage It is because rice grew rapidly atjointing-booting stage and absorbed more nitrogen resultingin the reduction in the concentration of NO
3
minus-N Submer-gence at jointing-booting stage significantly reduced the con-centration of NO
3
minus-N (Figure 4(b)) As shown in Figure 4(c)NO3
minus-N concentrations under the treatment T3 were lowerthan those under CK treatment during the submergenceexcept at the eighth day The concentration of NO
3
minus-N wasnot significantly decreased by submergence compared to CKAt milky stage it was observed that the concentration ofNO3
minus-N under T4 showed the trend of rise after first declineThis may be attributed to the decomposition of leaves sub-merged in water at milky stage The differences in the con-centration of NO
3
minus-N between T4 and CK were significant(Figure 4(d))
34 Potential of NH4+-N and NO3
minus-N Loss by Runoff duringSubmergence NH
4
+-N and NO3
minus-N losses by runoff indifferent treatments as influenced by submergence at differentstages during the year of 2010 were presented in Table 3 Aswas the case with surface water NH
4
+-N was the major com-ponent ofN in runoffwater RegardingNH
4
+-N andNO3
minus-Nloss by runoff at tillering stage the amount was decreased by76 and 83 by submergence (T1) as compared with the CKtreatment respectively The NH
4
+-N loss under T2 T3 andT4 was only 24 53 and 12 respectively of that underCK CID at jointing-booting panicle initiation and milkystages also decreases the amount of NO
3
minus-N loss by 91 91and 85 in relation to CK
4 Discussion
The increased attention being paid to the loss of nitrate viaagricultural drainage has led many to call for significantchanges in both management of N fertilizer and manage-ment of agricultural drainage systems [17] Overall currentagronomic guidelines which are primarily based on cropresponse may inadequately protect the water quality inSouthern China [18] Although positive results were obtainedby applying AWD technology in rice fields the drainagevolume in AWD has been reported to be larger due to theexcessive drainage requirement which results in an increasein nitrate losses from the agricultural fields [19 20] This canbe partially addressed by the introduction of irrigation anddrainage management This then allows drainage design andmanagement within the reasonable bounds expected forlong-term nitrate control [21]
6 Journal of Chemistry
00
10
20
30
40
50
CKT1
722 725 728719
NH
4
+-N
(mgmiddot
Lminus1)
(a)
814 817 820
CKT2
00
10
20
30
40
50
NH
4
+-N
(mgmiddot
Lminus1)
823
(b)
00
10
20
30
40
50
830 92 95 98
CKT3
NH
4
+-N
(mgmiddot
Lminus1)
(c)
CKT4
912 915 918 92100
10
20
30
40
50N
H4
+-N
(mgmiddot
Lminus1)
(d)
Figure 3 The change of the concentration of NH4
+-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
The various forms of N caused by the actions of microor-ganisms are dependent on temperature and time The sub-sequent movement of nitrate is dependent on the presenceof water in excess of field capacity This timing should corre-spond with the plantrsquos need for N Logically placement of Ninto the soil profile as a fertilizer addition would ideally be asclose to the time that a plant needs the nutrient as possibleto minimize the chance for loss into the environment In thisexperiment we observed that urea fertilization can signifi-cantly increase the concentration of NH
4
+-N and TN but hasa little influence on NO
3
minus-NThe major nitrogen treatment mechanisms of rice paddy
include microbial interactions with nitrogen sedimentation
chemical adsorption and plant uptake [22] In tradi-tional nitrogen treatments the biological nitrogen transitionrequires a two-step process nitrification followed by denitri-fication Nitrification implies a chemolithoautotrophic oxida-tion of ammonia to nitrate under strict aerobic conditionsThe nitrification process is very oxygen demanding Duringthe submergence the biological denitrification mechanismmakes use of nitrate as the terminal electron acceptor inlow-oxygen environments [23] Under CID condition theconcentrations of NH
4
+-N at four stages were higher thanthat of NO
3
minus-N As is shown in Table 3 NH4
+-N was themajor component of N in runoff water after submergenceSimilar results were also reported in paddy soil in Southern
Journal of Chemistry 7
00
03
06
09
12
15
CKT1
719 725 728722
NO
3
minus-N
(mgmiddot
Lminus1)
(a)
823
CKT2
82081781400
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(b)
00
03
06
09
12
15
9592830 98
CKT3
NO
3
minus-N
(mgmiddot
Lminus1)
(c)
918915912 921
CKT4
00
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(d)
Figure 4The change of the concentration of NO3
minus-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
Table 3 Nitrogen loss by runoff during the period of submergence in 2010
Form of N Tillering stage Jointing-booting stage Panicle initiation stage Milky stageT1 CK T2 CK T3 CK T4 CK
minus-N (gha) 36 plusmn 21 214 plusmn 102 42 plusmn 53 485 plusmn 198 84 plusmn 48 910 plusmn 438 30 plusmn 18 196 plusmn 93Note CK indicates alternate drying and wet irrigation T1 T2 T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiationstage and milky stage respectively Each value is the mean plusmn SD (119899 = 3)
China [24]This is because the nitrificationwas suppressed bylack of oxygen due to prolonged submergence The concen-tration of NH
4
+-N in surface water at tillering stage is higherthan that at the following three stages This is because thegrowth is strong at jointing-booting and panicle initiationstages which lead to the reduction of NH
4
+-N and NO3
minus-N
Generally nitrogen loss through drainage increases as Nrate and runoff volume increase especially as N rates aregreater than the economic optimum CID had been shownto decrease water flow [25] and thus supports results fromthis study Compared to CK the CID treatment significantlydecreases the loss of NH
4
+-N and NO3
minus-N indicating that
8 Journal of Chemistry
NH4
+-N and NO3
minus-N loads in the runoff were not only cor-related with runoff volume but also pertinent to NH
4
+-N andNO3
minus-N concentrations during given runoff eventsThis study only investigated the potential of CID at single
stage for reducing nitrogen emission from rice paddies inSouthern China It did not investigate the effect of CID at thecompound stages and the multistages and change of N aftersubmergence withdrawal More research needs to be carriedout in the future to define these relationships
5 Conclusions
In Southern China the water quality in paddy is easilyaffected by various forms ofNThe high rates of N applicationgenerally resulted in high concentrations of NH
4
+-N and TNin the surface water on the second day indicating the periodwith the highest risk of N runoff Compared to CK the con-centration of NO
3
minus-N in surface water showed some reduc-tion under CID at four stages but differed largely among thetreatments NH
4
+-Nwas themajor component of N in runoffwater after submergence at four stages Consistent with thereduction of drainage CID at four stages can significantlydecrease the amount of NO
3
minus-N and NH4
+-N losses byrunoff in relation to CK The study can be helpful for waterlevel management in rice paddy with compromise of watersaving reduction of N and high yield
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was funded by Key Program granted by theNational Nature amp Science Foundation of China (nos51479063 51279059 and 41271236) and supported by theSupporting Program of the ldquoOutstanding Young CreativeTalents in Hohai Universityrdquo ldquoOutstanding Scientific andTechnological Innovation Team in Jiangsu Colleges and Uni-versitiesrdquo and ldquothe Priority Academic Program Developmentof JiangsuHigher Education InstitutionsrdquoThe authors extendtheir gratitude to editor and the anonymous reviewers forsubstantial comments on earlier versions of this paper
References
[1] R W Skaggs D Amatya R O Evans and J E Parsons ldquoChar-acterization and evaluation of proposed hydrologic criteria forwetlandsrdquo Journal of Soil andWater Conservation vol 49 no 5pp 501ndash510 1994
[2] G W Randall and J A Vetsch ldquoNitrate losses in subsurfacedrainage from a corn-soybean rotation as affected by fall andspring application of nitrogen and nitrapyrinrdquo Journal of Envi-ronmental Quality vol 34 no 2 pp 590ndash597 2005
[3] N Chirinda J E Olesen J R Porter and P Schjoslashnning ldquoSoilproperties crop production and greenhouse gas emissions fromorganic and inorganic fertilizer-based arable cropping systemsrdquo
[4] K Wang R D Zhang and H Chen ldquoDrainage-process anal-yses for agricultural non-point-source pollution from irrigatedpaddy systemsrdquo Journal of Irrigation and Drainage Engineeringvol 140 Article ID 04013004 pp 1ndash14 2014
[5] P Belder B AM Bouman R Cabangon et al ldquoEffect of water-saving irrigation on rice yield and water use in typical lowlandconditions in AsiardquoAgriculturalWaterManagement vol 65 no3 pp 193ndash210 2004
[6] B A M Bouman ldquoA conceptual framework for the improve-ment of crop water productivity at different spatial scalesrdquoAgricultural Systems vol 93 no 1ndash3 pp 43ndash60 2007
[7] B A M Bouman E Humphreys T P Tuong and R BarkerldquoRice and waterrdquo Advances in Agronomy vol 92 pp 187ndash2372007
[8] G Shao J Cui S Yu et al ldquoImpacts of controlled irrigationand drainage on the yield and physiological attributes of riceImpacts of controlled irrigation and drainage on the yield andphysiological attributes of ricerdquo Agricultural Water Manage-ment vol 149 pp 156ndash165 2015
[9] K Surajit and D De Principles and Practices of Rice ProductionJohn Wiley amp Sons New York NY USA 1981
[10] C-G Lee T D Fletcher and G Sun ldquoNitrogen removal in con-structedwetland systemsrdquoEngineering in Life Sciences vol 9 no1 pp 11ndash22 2009
[11] Y Takai and T Kamura ldquoThe mechanism of reduction inwaterlogged paddy soilrdquo Folia Microbiologica vol 11 no 4 pp304ndash313 1966
[12] V Lalonde C A Madramootoo L Trenholm and R SBroughton ldquoEffects of controlled drainage onnitrate concentra-tions in subsurface drain dischargerdquo Agricultural Water Man-agement vol 29 no 2 pp 187ndash199 1996
[13] D Hesterberg B de Vos and P A C Raats ldquoChemistry ofsubsurface drain discharge from an agricultural polder soilrdquoAgricultural Water Management vol 86 no 1-2 pp 220ndash2282006
[14] M X Huang S Zhang Y J Tang and B X Chen ldquoNitrogenlosses from farm runoff under simulated rainfall conditionsrdquoSoil and Environmental Sciences vol 10 no 1 pp 6ndash10 2001
[15] IWesstrom and IMessing ldquoEffects of controlled drainage onNand P losses andNdynamics in a loamy sandwith spring cropsrdquoAgricultural Water Management vol 87 no 3 pp 229ndash2402007
[16] R O Evans R W Skaggs and J W Gilliam ldquoControlledversus conventional drainage effects on water qualityrdquo Journalof Irrigation and Drainage Engineering vol 121 no 4 pp 271ndash276 1995
[17] G W Randall and D J Mulla ldquoNitrate nitrogen in surfacewaters as influenced by climatic conditions and agriculturalpracticesrdquo Journal of Environmental Quality vol 30 no 2 pp337ndash344 2001
[18] Y-Q Zhang M-X Wen X-P Li and X-J Shi ldquoLong-termfertilisation causes excess supply and loss of phosphorus inpurple paddy soilrdquo Journal of the Science of Food andAgriculturevol 94 no 6 pp 1175ndash1183 2014
[19] X Guo J Yuan F Guo and Z Chen ldquoPreliminary study onwater-catching and controlled irrigation technology of ricerdquoTransactions of the Chinese Society of Agricultural Engineeringvol 25 no 4 pp 70ndash73 2009
Journal of Chemistry 9
[20] S E Yu Z M Miao W G Xing G C Shao and Y X JiangldquoResearch advance on irrigation and drainage for rice by usingfield water level as regulation indexrdquo Journal of Irrigation andDrainage vol 29 pp 134ndash136 2010 (Chinese)
[21] J E Ayars E W Christen and J W Hornbuckle ldquoControlleddrainage for improved water management in arid regionsirrigated agriculturerdquo Agricultural Water Management vol 86no 1-2 pp 128ndash139 2006
[22] N R Khatiwada andC Polprasert ldquoAssessment of effective spe-cific surface area for free water surface constructed wetlandsrdquoWater Science and Technology vol 40 no 3 pp 83ndash89 1999
[23] M Prosnansky Y Sakakibara and M Kuroda ldquoHigh-rate den-itrification and SS rejection by biofilm-electrode reactor (BER)combined with microfiltrationrdquoWater Research vol 36 no 19pp 4801ndash4810 2002
[24] X J Hu X H Shao Y Y Li J He S G Lu and Y Qiu ldquoEffectsof controlled and mid-gathering irrigation mode of paddy riceon the pollutants emission and reductionrdquo Energy Procedia vol16 pp 907ndash914 2012
[25] G-C Shao S Deng N Liu S-E Yu M-H Wang and D-LShe ldquoEffects of controlled irrigation and drainage on growthgrain yield and water use in paddy ricerdquo European Journal ofAgronomy vol 53 pp 1ndash9 2014
+-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
The various forms of N caused by the actions of microor-ganisms are dependent on temperature and time The sub-sequent movement of nitrate is dependent on the presenceof water in excess of field capacity This timing should corre-spond with the plantrsquos need for N Logically placement of Ninto the soil profile as a fertilizer addition would ideally be asclose to the time that a plant needs the nutrient as possibleto minimize the chance for loss into the environment In thisexperiment we observed that urea fertilization can signifi-cantly increase the concentration of NH
4
+-N and TN but hasa little influence on NO
3
minus-NThe major nitrogen treatment mechanisms of rice paddy
include microbial interactions with nitrogen sedimentation
chemical adsorption and plant uptake [22] In tradi-tional nitrogen treatments the biological nitrogen transitionrequires a two-step process nitrification followed by denitri-fication Nitrification implies a chemolithoautotrophic oxida-tion of ammonia to nitrate under strict aerobic conditionsThe nitrification process is very oxygen demanding Duringthe submergence the biological denitrification mechanismmakes use of nitrate as the terminal electron acceptor inlow-oxygen environments [23] Under CID condition theconcentrations of NH
4
+-N at four stages were higher thanthat of NO
3
minus-N As is shown in Table 3 NH4
+-N was themajor component of N in runoff water after submergenceSimilar results were also reported in paddy soil in Southern
Journal of Chemistry 7
00
03
06
09
12
15
CKT1
719 725 728722
NO
3
minus-N
(mgmiddot
Lminus1)
(a)
823
CKT2
82081781400
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(b)
00
03
06
09
12
15
9592830 98
CKT3
NO
3
minus-N
(mgmiddot
Lminus1)
(c)
918915912 921
CKT4
00
03
06
09
12
15
NO
3
minus-N
(mgmiddot
Lminus1)
(d)
Figure 4The change of the concentration of NO3
minus-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
Table 3 Nitrogen loss by runoff during the period of submergence in 2010
Form of N Tillering stage Jointing-booting stage Panicle initiation stage Milky stageT1 CK T2 CK T3 CK T4 CK
minus-N (gha) 36 plusmn 21 214 plusmn 102 42 plusmn 53 485 plusmn 198 84 plusmn 48 910 plusmn 438 30 plusmn 18 196 plusmn 93Note CK indicates alternate drying and wet irrigation T1 T2 T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiationstage and milky stage respectively Each value is the mean plusmn SD (119899 = 3)
China [24]This is because the nitrificationwas suppressed bylack of oxygen due to prolonged submergence The concen-tration of NH
4
+-N in surface water at tillering stage is higherthan that at the following three stages This is because thegrowth is strong at jointing-booting and panicle initiationstages which lead to the reduction of NH
4
+-N and NO3
minus-N
Generally nitrogen loss through drainage increases as Nrate and runoff volume increase especially as N rates aregreater than the economic optimum CID had been shownto decrease water flow [25] and thus supports results fromthis study Compared to CK the CID treatment significantlydecreases the loss of NH
4
+-N and NO3
minus-N indicating that
8 Journal of Chemistry
NH4
+-N and NO3
minus-N loads in the runoff were not only cor-related with runoff volume but also pertinent to NH
4
+-N andNO3
minus-N concentrations during given runoff eventsThis study only investigated the potential of CID at single
stage for reducing nitrogen emission from rice paddies inSouthern China It did not investigate the effect of CID at thecompound stages and the multistages and change of N aftersubmergence withdrawal More research needs to be carriedout in the future to define these relationships
5 Conclusions
In Southern China the water quality in paddy is easilyaffected by various forms ofNThe high rates of N applicationgenerally resulted in high concentrations of NH
4
+-N and TNin the surface water on the second day indicating the periodwith the highest risk of N runoff Compared to CK the con-centration of NO
3
minus-N in surface water showed some reduc-tion under CID at four stages but differed largely among thetreatments NH
4
+-Nwas themajor component of N in runoffwater after submergence at four stages Consistent with thereduction of drainage CID at four stages can significantlydecrease the amount of NO
3
minus-N and NH4
+-N losses byrunoff in relation to CK The study can be helpful for waterlevel management in rice paddy with compromise of watersaving reduction of N and high yield
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was funded by Key Program granted by theNational Nature amp Science Foundation of China (nos51479063 51279059 and 41271236) and supported by theSupporting Program of the ldquoOutstanding Young CreativeTalents in Hohai Universityrdquo ldquoOutstanding Scientific andTechnological Innovation Team in Jiangsu Colleges and Uni-versitiesrdquo and ldquothe Priority Academic Program Developmentof JiangsuHigher Education InstitutionsrdquoThe authors extendtheir gratitude to editor and the anonymous reviewers forsubstantial comments on earlier versions of this paper
References
[1] R W Skaggs D Amatya R O Evans and J E Parsons ldquoChar-acterization and evaluation of proposed hydrologic criteria forwetlandsrdquo Journal of Soil andWater Conservation vol 49 no 5pp 501ndash510 1994
[2] G W Randall and J A Vetsch ldquoNitrate losses in subsurfacedrainage from a corn-soybean rotation as affected by fall andspring application of nitrogen and nitrapyrinrdquo Journal of Envi-ronmental Quality vol 34 no 2 pp 590ndash597 2005
[3] N Chirinda J E Olesen J R Porter and P Schjoslashnning ldquoSoilproperties crop production and greenhouse gas emissions fromorganic and inorganic fertilizer-based arable cropping systemsrdquo
[4] K Wang R D Zhang and H Chen ldquoDrainage-process anal-yses for agricultural non-point-source pollution from irrigatedpaddy systemsrdquo Journal of Irrigation and Drainage Engineeringvol 140 Article ID 04013004 pp 1ndash14 2014
[5] P Belder B AM Bouman R Cabangon et al ldquoEffect of water-saving irrigation on rice yield and water use in typical lowlandconditions in AsiardquoAgriculturalWaterManagement vol 65 no3 pp 193ndash210 2004
[6] B A M Bouman ldquoA conceptual framework for the improve-ment of crop water productivity at different spatial scalesrdquoAgricultural Systems vol 93 no 1ndash3 pp 43ndash60 2007
[7] B A M Bouman E Humphreys T P Tuong and R BarkerldquoRice and waterrdquo Advances in Agronomy vol 92 pp 187ndash2372007
[8] G Shao J Cui S Yu et al ldquoImpacts of controlled irrigationand drainage on the yield and physiological attributes of riceImpacts of controlled irrigation and drainage on the yield andphysiological attributes of ricerdquo Agricultural Water Manage-ment vol 149 pp 156ndash165 2015
[9] K Surajit and D De Principles and Practices of Rice ProductionJohn Wiley amp Sons New York NY USA 1981
[10] C-G Lee T D Fletcher and G Sun ldquoNitrogen removal in con-structedwetland systemsrdquoEngineering in Life Sciences vol 9 no1 pp 11ndash22 2009
[11] Y Takai and T Kamura ldquoThe mechanism of reduction inwaterlogged paddy soilrdquo Folia Microbiologica vol 11 no 4 pp304ndash313 1966
[12] V Lalonde C A Madramootoo L Trenholm and R SBroughton ldquoEffects of controlled drainage onnitrate concentra-tions in subsurface drain dischargerdquo Agricultural Water Man-agement vol 29 no 2 pp 187ndash199 1996
[13] D Hesterberg B de Vos and P A C Raats ldquoChemistry ofsubsurface drain discharge from an agricultural polder soilrdquoAgricultural Water Management vol 86 no 1-2 pp 220ndash2282006
[14] M X Huang S Zhang Y J Tang and B X Chen ldquoNitrogenlosses from farm runoff under simulated rainfall conditionsrdquoSoil and Environmental Sciences vol 10 no 1 pp 6ndash10 2001
[15] IWesstrom and IMessing ldquoEffects of controlled drainage onNand P losses andNdynamics in a loamy sandwith spring cropsrdquoAgricultural Water Management vol 87 no 3 pp 229ndash2402007
[16] R O Evans R W Skaggs and J W Gilliam ldquoControlledversus conventional drainage effects on water qualityrdquo Journalof Irrigation and Drainage Engineering vol 121 no 4 pp 271ndash276 1995
[17] G W Randall and D J Mulla ldquoNitrate nitrogen in surfacewaters as influenced by climatic conditions and agriculturalpracticesrdquo Journal of Environmental Quality vol 30 no 2 pp337ndash344 2001
[18] Y-Q Zhang M-X Wen X-P Li and X-J Shi ldquoLong-termfertilisation causes excess supply and loss of phosphorus inpurple paddy soilrdquo Journal of the Science of Food andAgriculturevol 94 no 6 pp 1175ndash1183 2014
[19] X Guo J Yuan F Guo and Z Chen ldquoPreliminary study onwater-catching and controlled irrigation technology of ricerdquoTransactions of the Chinese Society of Agricultural Engineeringvol 25 no 4 pp 70ndash73 2009
Journal of Chemistry 9
[20] S E Yu Z M Miao W G Xing G C Shao and Y X JiangldquoResearch advance on irrigation and drainage for rice by usingfield water level as regulation indexrdquo Journal of Irrigation andDrainage vol 29 pp 134ndash136 2010 (Chinese)
[21] J E Ayars E W Christen and J W Hornbuckle ldquoControlleddrainage for improved water management in arid regionsirrigated agriculturerdquo Agricultural Water Management vol 86no 1-2 pp 128ndash139 2006
[22] N R Khatiwada andC Polprasert ldquoAssessment of effective spe-cific surface area for free water surface constructed wetlandsrdquoWater Science and Technology vol 40 no 3 pp 83ndash89 1999
[23] M Prosnansky Y Sakakibara and M Kuroda ldquoHigh-rate den-itrification and SS rejection by biofilm-electrode reactor (BER)combined with microfiltrationrdquoWater Research vol 36 no 19pp 4801ndash4810 2002
[24] X J Hu X H Shao Y Y Li J He S G Lu and Y Qiu ldquoEffectsof controlled and mid-gathering irrigation mode of paddy riceon the pollutants emission and reductionrdquo Energy Procedia vol16 pp 907ndash914 2012
[25] G-C Shao S Deng N Liu S-E Yu M-H Wang and D-LShe ldquoEffects of controlled irrigation and drainage on growthgrain yield and water use in paddy ricerdquo European Journal ofAgronomy vol 53 pp 1ndash9 2014
minus-N during submergence in 2010 CK indicates alternate drying and wet irrigation T1 T2T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiation stage and milky stage respectively Verticalbars represent plusmn standard error (SE) of the mean
Table 3 Nitrogen loss by runoff during the period of submergence in 2010
Form of N Tillering stage Jointing-booting stage Panicle initiation stage Milky stageT1 CK T2 CK T3 CK T4 CK
minus-N (gha) 36 plusmn 21 214 plusmn 102 42 plusmn 53 485 plusmn 198 84 plusmn 48 910 plusmn 438 30 plusmn 18 196 plusmn 93Note CK indicates alternate drying and wet irrigation T1 T2 T3 and T4 denote the submergence at tillering stage jointing-booting stage panicle initiationstage and milky stage respectively Each value is the mean plusmn SD (119899 = 3)
China [24]This is because the nitrificationwas suppressed bylack of oxygen due to prolonged submergence The concen-tration of NH
4
+-N in surface water at tillering stage is higherthan that at the following three stages This is because thegrowth is strong at jointing-booting and panicle initiationstages which lead to the reduction of NH
4
+-N and NO3
minus-N
Generally nitrogen loss through drainage increases as Nrate and runoff volume increase especially as N rates aregreater than the economic optimum CID had been shownto decrease water flow [25] and thus supports results fromthis study Compared to CK the CID treatment significantlydecreases the loss of NH
4
+-N and NO3
minus-N indicating that
8 Journal of Chemistry
NH4
+-N and NO3
minus-N loads in the runoff were not only cor-related with runoff volume but also pertinent to NH
4
+-N andNO3
minus-N concentrations during given runoff eventsThis study only investigated the potential of CID at single
stage for reducing nitrogen emission from rice paddies inSouthern China It did not investigate the effect of CID at thecompound stages and the multistages and change of N aftersubmergence withdrawal More research needs to be carriedout in the future to define these relationships
5 Conclusions
In Southern China the water quality in paddy is easilyaffected by various forms ofNThe high rates of N applicationgenerally resulted in high concentrations of NH
4
+-N and TNin the surface water on the second day indicating the periodwith the highest risk of N runoff Compared to CK the con-centration of NO
3
minus-N in surface water showed some reduc-tion under CID at four stages but differed largely among thetreatments NH
4
+-Nwas themajor component of N in runoffwater after submergence at four stages Consistent with thereduction of drainage CID at four stages can significantlydecrease the amount of NO
3
minus-N and NH4
+-N losses byrunoff in relation to CK The study can be helpful for waterlevel management in rice paddy with compromise of watersaving reduction of N and high yield
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was funded by Key Program granted by theNational Nature amp Science Foundation of China (nos51479063 51279059 and 41271236) and supported by theSupporting Program of the ldquoOutstanding Young CreativeTalents in Hohai Universityrdquo ldquoOutstanding Scientific andTechnological Innovation Team in Jiangsu Colleges and Uni-versitiesrdquo and ldquothe Priority Academic Program Developmentof JiangsuHigher Education InstitutionsrdquoThe authors extendtheir gratitude to editor and the anonymous reviewers forsubstantial comments on earlier versions of this paper
References
[1] R W Skaggs D Amatya R O Evans and J E Parsons ldquoChar-acterization and evaluation of proposed hydrologic criteria forwetlandsrdquo Journal of Soil andWater Conservation vol 49 no 5pp 501ndash510 1994
[2] G W Randall and J A Vetsch ldquoNitrate losses in subsurfacedrainage from a corn-soybean rotation as affected by fall andspring application of nitrogen and nitrapyrinrdquo Journal of Envi-ronmental Quality vol 34 no 2 pp 590ndash597 2005
[3] N Chirinda J E Olesen J R Porter and P Schjoslashnning ldquoSoilproperties crop production and greenhouse gas emissions fromorganic and inorganic fertilizer-based arable cropping systemsrdquo
[4] K Wang R D Zhang and H Chen ldquoDrainage-process anal-yses for agricultural non-point-source pollution from irrigatedpaddy systemsrdquo Journal of Irrigation and Drainage Engineeringvol 140 Article ID 04013004 pp 1ndash14 2014
[5] P Belder B AM Bouman R Cabangon et al ldquoEffect of water-saving irrigation on rice yield and water use in typical lowlandconditions in AsiardquoAgriculturalWaterManagement vol 65 no3 pp 193ndash210 2004
[6] B A M Bouman ldquoA conceptual framework for the improve-ment of crop water productivity at different spatial scalesrdquoAgricultural Systems vol 93 no 1ndash3 pp 43ndash60 2007
[7] B A M Bouman E Humphreys T P Tuong and R BarkerldquoRice and waterrdquo Advances in Agronomy vol 92 pp 187ndash2372007
[8] G Shao J Cui S Yu et al ldquoImpacts of controlled irrigationand drainage on the yield and physiological attributes of riceImpacts of controlled irrigation and drainage on the yield andphysiological attributes of ricerdquo Agricultural Water Manage-ment vol 149 pp 156ndash165 2015
[9] K Surajit and D De Principles and Practices of Rice ProductionJohn Wiley amp Sons New York NY USA 1981
[10] C-G Lee T D Fletcher and G Sun ldquoNitrogen removal in con-structedwetland systemsrdquoEngineering in Life Sciences vol 9 no1 pp 11ndash22 2009
[11] Y Takai and T Kamura ldquoThe mechanism of reduction inwaterlogged paddy soilrdquo Folia Microbiologica vol 11 no 4 pp304ndash313 1966
[12] V Lalonde C A Madramootoo L Trenholm and R SBroughton ldquoEffects of controlled drainage onnitrate concentra-tions in subsurface drain dischargerdquo Agricultural Water Man-agement vol 29 no 2 pp 187ndash199 1996
[13] D Hesterberg B de Vos and P A C Raats ldquoChemistry ofsubsurface drain discharge from an agricultural polder soilrdquoAgricultural Water Management vol 86 no 1-2 pp 220ndash2282006
[14] M X Huang S Zhang Y J Tang and B X Chen ldquoNitrogenlosses from farm runoff under simulated rainfall conditionsrdquoSoil and Environmental Sciences vol 10 no 1 pp 6ndash10 2001
[15] IWesstrom and IMessing ldquoEffects of controlled drainage onNand P losses andNdynamics in a loamy sandwith spring cropsrdquoAgricultural Water Management vol 87 no 3 pp 229ndash2402007
[16] R O Evans R W Skaggs and J W Gilliam ldquoControlledversus conventional drainage effects on water qualityrdquo Journalof Irrigation and Drainage Engineering vol 121 no 4 pp 271ndash276 1995
[17] G W Randall and D J Mulla ldquoNitrate nitrogen in surfacewaters as influenced by climatic conditions and agriculturalpracticesrdquo Journal of Environmental Quality vol 30 no 2 pp337ndash344 2001
[18] Y-Q Zhang M-X Wen X-P Li and X-J Shi ldquoLong-termfertilisation causes excess supply and loss of phosphorus inpurple paddy soilrdquo Journal of the Science of Food andAgriculturevol 94 no 6 pp 1175ndash1183 2014
[19] X Guo J Yuan F Guo and Z Chen ldquoPreliminary study onwater-catching and controlled irrigation technology of ricerdquoTransactions of the Chinese Society of Agricultural Engineeringvol 25 no 4 pp 70ndash73 2009
Journal of Chemistry 9
[20] S E Yu Z M Miao W G Xing G C Shao and Y X JiangldquoResearch advance on irrigation and drainage for rice by usingfield water level as regulation indexrdquo Journal of Irrigation andDrainage vol 29 pp 134ndash136 2010 (Chinese)
[21] J E Ayars E W Christen and J W Hornbuckle ldquoControlleddrainage for improved water management in arid regionsirrigated agriculturerdquo Agricultural Water Management vol 86no 1-2 pp 128ndash139 2006
[22] N R Khatiwada andC Polprasert ldquoAssessment of effective spe-cific surface area for free water surface constructed wetlandsrdquoWater Science and Technology vol 40 no 3 pp 83ndash89 1999
[23] M Prosnansky Y Sakakibara and M Kuroda ldquoHigh-rate den-itrification and SS rejection by biofilm-electrode reactor (BER)combined with microfiltrationrdquoWater Research vol 36 no 19pp 4801ndash4810 2002
[24] X J Hu X H Shao Y Y Li J He S G Lu and Y Qiu ldquoEffectsof controlled and mid-gathering irrigation mode of paddy riceon the pollutants emission and reductionrdquo Energy Procedia vol16 pp 907ndash914 2012
[25] G-C Shao S Deng N Liu S-E Yu M-H Wang and D-LShe ldquoEffects of controlled irrigation and drainage on growthgrain yield and water use in paddy ricerdquo European Journal ofAgronomy vol 53 pp 1ndash9 2014
minus-N loads in the runoff were not only cor-related with runoff volume but also pertinent to NH
4
+-N andNO3
minus-N concentrations during given runoff eventsThis study only investigated the potential of CID at single
stage for reducing nitrogen emission from rice paddies inSouthern China It did not investigate the effect of CID at thecompound stages and the multistages and change of N aftersubmergence withdrawal More research needs to be carriedout in the future to define these relationships
5 Conclusions
In Southern China the water quality in paddy is easilyaffected by various forms ofNThe high rates of N applicationgenerally resulted in high concentrations of NH
4
+-N and TNin the surface water on the second day indicating the periodwith the highest risk of N runoff Compared to CK the con-centration of NO
3
minus-N in surface water showed some reduc-tion under CID at four stages but differed largely among thetreatments NH
4
+-Nwas themajor component of N in runoffwater after submergence at four stages Consistent with thereduction of drainage CID at four stages can significantlydecrease the amount of NO
3
minus-N and NH4
+-N losses byrunoff in relation to CK The study can be helpful for waterlevel management in rice paddy with compromise of watersaving reduction of N and high yield
Conflict of Interests
The authors declare that there is no conflict of interestsregarding the publication of this paper
Acknowledgments
This work was funded by Key Program granted by theNational Nature amp Science Foundation of China (nos51479063 51279059 and 41271236) and supported by theSupporting Program of the ldquoOutstanding Young CreativeTalents in Hohai Universityrdquo ldquoOutstanding Scientific andTechnological Innovation Team in Jiangsu Colleges and Uni-versitiesrdquo and ldquothe Priority Academic Program Developmentof JiangsuHigher Education InstitutionsrdquoThe authors extendtheir gratitude to editor and the anonymous reviewers forsubstantial comments on earlier versions of this paper
References
[1] R W Skaggs D Amatya R O Evans and J E Parsons ldquoChar-acterization and evaluation of proposed hydrologic criteria forwetlandsrdquo Journal of Soil andWater Conservation vol 49 no 5pp 501ndash510 1994
[2] G W Randall and J A Vetsch ldquoNitrate losses in subsurfacedrainage from a corn-soybean rotation as affected by fall andspring application of nitrogen and nitrapyrinrdquo Journal of Envi-ronmental Quality vol 34 no 2 pp 590ndash597 2005
[3] N Chirinda J E Olesen J R Porter and P Schjoslashnning ldquoSoilproperties crop production and greenhouse gas emissions fromorganic and inorganic fertilizer-based arable cropping systemsrdquo
[4] K Wang R D Zhang and H Chen ldquoDrainage-process anal-yses for agricultural non-point-source pollution from irrigatedpaddy systemsrdquo Journal of Irrigation and Drainage Engineeringvol 140 Article ID 04013004 pp 1ndash14 2014
[5] P Belder B AM Bouman R Cabangon et al ldquoEffect of water-saving irrigation on rice yield and water use in typical lowlandconditions in AsiardquoAgriculturalWaterManagement vol 65 no3 pp 193ndash210 2004
[6] B A M Bouman ldquoA conceptual framework for the improve-ment of crop water productivity at different spatial scalesrdquoAgricultural Systems vol 93 no 1ndash3 pp 43ndash60 2007
[7] B A M Bouman E Humphreys T P Tuong and R BarkerldquoRice and waterrdquo Advances in Agronomy vol 92 pp 187ndash2372007
[8] G Shao J Cui S Yu et al ldquoImpacts of controlled irrigationand drainage on the yield and physiological attributes of riceImpacts of controlled irrigation and drainage on the yield andphysiological attributes of ricerdquo Agricultural Water Manage-ment vol 149 pp 156ndash165 2015
[9] K Surajit and D De Principles and Practices of Rice ProductionJohn Wiley amp Sons New York NY USA 1981
[10] C-G Lee T D Fletcher and G Sun ldquoNitrogen removal in con-structedwetland systemsrdquoEngineering in Life Sciences vol 9 no1 pp 11ndash22 2009
[11] Y Takai and T Kamura ldquoThe mechanism of reduction inwaterlogged paddy soilrdquo Folia Microbiologica vol 11 no 4 pp304ndash313 1966
[12] V Lalonde C A Madramootoo L Trenholm and R SBroughton ldquoEffects of controlled drainage onnitrate concentra-tions in subsurface drain dischargerdquo Agricultural Water Man-agement vol 29 no 2 pp 187ndash199 1996
[13] D Hesterberg B de Vos and P A C Raats ldquoChemistry ofsubsurface drain discharge from an agricultural polder soilrdquoAgricultural Water Management vol 86 no 1-2 pp 220ndash2282006
[14] M X Huang S Zhang Y J Tang and B X Chen ldquoNitrogenlosses from farm runoff under simulated rainfall conditionsrdquoSoil and Environmental Sciences vol 10 no 1 pp 6ndash10 2001
[15] IWesstrom and IMessing ldquoEffects of controlled drainage onNand P losses andNdynamics in a loamy sandwith spring cropsrdquoAgricultural Water Management vol 87 no 3 pp 229ndash2402007
[16] R O Evans R W Skaggs and J W Gilliam ldquoControlledversus conventional drainage effects on water qualityrdquo Journalof Irrigation and Drainage Engineering vol 121 no 4 pp 271ndash276 1995
[17] G W Randall and D J Mulla ldquoNitrate nitrogen in surfacewaters as influenced by climatic conditions and agriculturalpracticesrdquo Journal of Environmental Quality vol 30 no 2 pp337ndash344 2001
[18] Y-Q Zhang M-X Wen X-P Li and X-J Shi ldquoLong-termfertilisation causes excess supply and loss of phosphorus inpurple paddy soilrdquo Journal of the Science of Food andAgriculturevol 94 no 6 pp 1175ndash1183 2014
[19] X Guo J Yuan F Guo and Z Chen ldquoPreliminary study onwater-catching and controlled irrigation technology of ricerdquoTransactions of the Chinese Society of Agricultural Engineeringvol 25 no 4 pp 70ndash73 2009
Journal of Chemistry 9
[20] S E Yu Z M Miao W G Xing G C Shao and Y X JiangldquoResearch advance on irrigation and drainage for rice by usingfield water level as regulation indexrdquo Journal of Irrigation andDrainage vol 29 pp 134ndash136 2010 (Chinese)
[21] J E Ayars E W Christen and J W Hornbuckle ldquoControlleddrainage for improved water management in arid regionsirrigated agriculturerdquo Agricultural Water Management vol 86no 1-2 pp 128ndash139 2006
[22] N R Khatiwada andC Polprasert ldquoAssessment of effective spe-cific surface area for free water surface constructed wetlandsrdquoWater Science and Technology vol 40 no 3 pp 83ndash89 1999
[23] M Prosnansky Y Sakakibara and M Kuroda ldquoHigh-rate den-itrification and SS rejection by biofilm-electrode reactor (BER)combined with microfiltrationrdquoWater Research vol 36 no 19pp 4801ndash4810 2002
[24] X J Hu X H Shao Y Y Li J He S G Lu and Y Qiu ldquoEffectsof controlled and mid-gathering irrigation mode of paddy riceon the pollutants emission and reductionrdquo Energy Procedia vol16 pp 907ndash914 2012
[25] G-C Shao S Deng N Liu S-E Yu M-H Wang and D-LShe ldquoEffects of controlled irrigation and drainage on growthgrain yield and water use in paddy ricerdquo European Journal ofAgronomy vol 53 pp 1ndash9 2014
[20] S E Yu Z M Miao W G Xing G C Shao and Y X JiangldquoResearch advance on irrigation and drainage for rice by usingfield water level as regulation indexrdquo Journal of Irrigation andDrainage vol 29 pp 134ndash136 2010 (Chinese)
[21] J E Ayars E W Christen and J W Hornbuckle ldquoControlleddrainage for improved water management in arid regionsirrigated agriculturerdquo Agricultural Water Management vol 86no 1-2 pp 128ndash139 2006
[22] N R Khatiwada andC Polprasert ldquoAssessment of effective spe-cific surface area for free water surface constructed wetlandsrdquoWater Science and Technology vol 40 no 3 pp 83ndash89 1999
[23] M Prosnansky Y Sakakibara and M Kuroda ldquoHigh-rate den-itrification and SS rejection by biofilm-electrode reactor (BER)combined with microfiltrationrdquoWater Research vol 36 no 19pp 4801ndash4810 2002
[24] X J Hu X H Shao Y Y Li J He S G Lu and Y Qiu ldquoEffectsof controlled and mid-gathering irrigation mode of paddy riceon the pollutants emission and reductionrdquo Energy Procedia vol16 pp 907ndash914 2012
[25] G-C Shao S Deng N Liu S-E Yu M-H Wang and D-LShe ldquoEffects of controlled irrigation and drainage on growthgrain yield and water use in paddy ricerdquo European Journal ofAgronomy vol 53 pp 1ndash9 2014
