EFFECT OF RECLAIMED MUNICIPAL WASTEWATER IRRIGATION AND NITROGEN FERTILIZATION ON YIELD OF TOMATO AND NITROGEN ECONOMY

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1 Bngldesh J. Bot. 44(5): , 2015 (December), Supplementry EFFECT OF RECLAIMED MUNICIPAL WASTEWATER IRRIGATION AND NITROGEN FERTILIZATION ON YIELD OF TOMATO AND NITROGEN ECONOMY PING LI, CHAO HU 1, XUEBIN QI 1*, YUAN ZHOU 2, ZHANG JIANFENG AND ZHIJUAN ZHAO 3 XI AN University of Technology, Institute of Wter Resources nd Hydro-electric Engineering, Xi n, Shnxi , Chin Key words: Greenhouse tomto, Rhizosphere, Prtil fctor productivity, Apprent N loss Abstrct To exmine the effects of nitrogen nd reclimed municipl wstewter irrigtion on yield of greenhouse tomto nd nitrogen economy, field experiments were crried out. Root-lyer minerl nitrogen, totl nitrogen, bundnce of soil microorgnisms, tomto yield, nitrogen in fruit, prtil fctor productivity from pplied N, pprent N loss nd nitrogen supplying cpcity were nlyzed. The results indicted tht RMW irrigtion leded to n verge of % increse in minerl nitrogen nd totl nitrogen of rhizosphere soil in 1st, 2nd nd 4th cluster fruit expnding stge. RMW irrigtion significntly incresed the microbil popultion of rhizosphere soil in the crop growth stge, yield of tomto, nitrogen in fruit, prtil fctor productivity from pplied N nd nitrogen supplying cpcity. RMW irrigtion reduced the mount of topdressed nitrogen nd promoted rhizosphere nitrogen supplying cpcity nd this prevent disposl of RMW to the river nd minimize groundwter exploittion. Introduction Strting in the 1980s, Chin begn to reclim municipl wstewter (RMW) irrigtion in order to ddress the differences between wter supply nd demnd for wter nd to improve griculture wter mngement through reserch technology. In recent yers, the testing nd ppliction of RMW irrigtion hve been implemented in Beijing, Tinjin, Dlin nd other plces (Shi et l. 2008). With rpid increses in the prctice of irrigting with RMW, mny environmentl problems hve occurred. Surfce soil ccumultion of microorgnisms, slts, orgnic contminnts, nd hevy metls hve resulted in humn helth risks, soil degrdtion, declines in production cpcity, etc. (Ftt-Kssinos et l. 2010, Pereri et l. 2011, Michel et l. 2012). Excessive soil nitrifiction from wstewter irrigtion hs resulted in mrked increse in soil cidity since the 1980s (Guo et l. 2010). RMW derived from urbn sewge hs higher concentrtions of N, P, K, C, Mg (Fonsec et l. 2007, Sophocleous et l. 2009), which could ccumulte in surfce soils. Croplnd soil production cpcity therefore, becoming worse with RMW irrigtion under conventionl fertiliztion regime. The rhizosphere is the micro-zone surrounding the root system, it rnges from less thn 1 to few mm thickness nd provides the portl for wter nd minerl nutrients to enter the root system. Chemicl nd physicl soil properties, microorgnism community structure, soil nutrient sttus, nd root secretions ll influence the biologicl cycle nd gretly influence plnt growth, nutrient use Author for correspondence:<firilp@163.com>. 1 Frmlnd Irrigtion Reserch Institute, Chinese Acdemy of Agriculturl Sciences, Xinxing , Chin. 2 Chinese Acdemy of Agriculturl Sciences, Agriculture Wter nd Soil Environmentl Field Science Reserch Sttion of Xinxing city, Henn province, Xinxing , Chin. 3 Key lbortory of high-efficient nd sfe utiliztion of griculture wter resources, Chinese Acdemy of Agriculturl Sciences, Xinxing , Chin.

2 700 LI et l. efficiency, nd the yield of biochemicl processes (Hinsinger et l. 2009, Fn et l. 2012, Dinesh et l. 2012). Minerl nitrogen in rhizosphere soil ws found to be significntly lower thn in surrounding soil owing to incresed microbil immobiliztion nd root uptke (Zho et l. 2010), the bundnce of rhizosphere microbil ws significntly higher thn tht of the surrounding soil. Enzymtic ctivity ssocited with soil microorgnisms further chnged the vilbility of soil nutrients (Rouphel et l. 2005, Gun et l. 2011, Kołodziej et l. 2012). Plnt growth-promoting rhizobcteri re free-living bcteri which ctively colonize plnt roots, exerting beneficil effects on plnt development (Pérez-Montno et l. 2014). However, sound understnding of the mechnisms of rhizosphere soil nitrogen supplying cpcity is importnt in order to decide how mount of nitrogen to be topdressed for mximizing yield of greenhouse tomto irrigted with RMW. In this work, ttempt ws mde to scertin the nitrogen supplying cpcity of the tomto rhizosphere nd the reltionship between yield determining fctors irrigted with RMW. Finlly, trgets were considered for reducing the mount of fertilizer in reltion to nitrogen utiliztion nd RMW irrigtion. Mterils nd Methods Field experiments were crried out on 2013 in greenhouse t the Agriculture Wter nd Soil Environmentl Field Science Reserch Sttion, Chinese Acdemy of Agriculturl Science, Xinxing city, Henn province, Chin (ltitude N, longitude E, nd ltitude 73.2m). Xinxing city hs temperte climte with n nnul verge rinfll of bout mm. The RMW for irrigtion ws tken from the Luotuo Wn wter source plnt in Xinxing city Henn province. From Luotuo Wn wter source plnt, under tretment process of nerobic-noxic-oxic denitrifiction biofilter nd ozone oxidtion. Municipl sewge ws the min source of wstewter for the plnt, bsic properties of RMW nd tp wter used were listed in the Tble 1. The field tril ws fully rndomized design with three replictes of five tretments (ReN1, ReN2, ReN3, ReN4 nd CK) using RMW nd tp wter irrigtion with subsurfce drip irrigtion systems. The ReN1, ReN2, ReN3, ReN4 nd CK tretments consisted of nitrogen topdressing s 90, 72, 63, 45 nd 90 kg/hm 2, respectively. Bse fertilizers included dried chicken mnure, nitrogen, phosphorus, potssium fertilizers, rted t 8 000, 180, 180 nd 180 kg/hm 2, respectively. Irrigtion scheduling ws bsed on soil wter content, s mesured by Time Domin Reflectometer (TDR). Plots of RMW tretments were irrigted two times with tp wter during seedling stge, nd with RMW fter the blooming nd fruit setting period. Furthermore, plots of CK tretment were irrigted with tp wter during the growth spn of tomto. The totl irrigtion mounted ws 3736 m 3 /hm 2. The trditionl strip plnting regime for tomtoes ws used, which hd border width intervl of m, row spcing of 0.3 m, line spcing of 0.75 m nd plnting density of plnts per hectre. Tomto plnts were trnsplnted on Mrch 23, 2013 nd tomtoes were hrvested on July 27, Tomto plnts were evluted t the developmentl stges consisting of 5 clusters nd topdressing with nitrogen ws performed t the 1st, 2nd nd 4th cluster fruit expnding stge. Other mngement prctices during the whole growth seson were completely stndrd. Soil strongly dhering to the roots ws considered to belong to the rhizosphere (Chen et l. 2006) nd ws collected for nlysis. Bulk soils were smpled from loction pproximtely 15 cm from the root t the 1st, 2nd nd 4th cluster fruit expnding stge nd lte growth stge (Grci et l. 2005). Soil smples were collected t depth of 0-10 cm, cm, cm, cm nd cm with stndrd 3.5 cm Ø soil uger t tomto trnsplnting nd hrvest stges, 5 smples

3 EFFECT OF RECLAIMED MUNICIPAL WASTEWATER IRRIGATION 701 were collected per plot nd stored t room temperture before nlyzing for NO 3 -N, NH 4 -N, totl N, Totl P, K, ph nd totl counting of bcteri. Three plnt smples per plot were tken post-hrvest, stored t room temperture, smples were nlyzed for NO 3 -N, NH 4 -N, totl N, vilble P nd K in root, stem, lef nd fresh fruit. Tble 1. Properties of reclimed municipl wstewter nd tp wter used. Dte of NO - 3-N NH + 4 -N Totl N Totl P Cu Totl Cd COD Mn TDS ph smpling (mg/l) (mg/l) (mg/l) (mg/l) (mg/l) (µg/l) (µg/l) (g/l) (g/l) COD = Chemicl oxygen demnd, TDS = Totl dissolved slt. Anlysis of vrince (ANOVA) ws performed with one-wy ANOVA using DPS14.50 softwre. Tretments were compred for significnt differences (p <0.05 level) using DMRT. Cr 6+ Results nd Discussion The rhizosphere soil minerl nitrogen content of ReN1, ReN2, ReN3, ReN4 nd CK ws lower thn tht of bulk soil by 27.59, 10.47, 10.89, 0.96 nd 19.26% in the 1st cluster fruit expnding stge, nd by 15.82, 12.63, 11.66, 1.33 nd 12.69% in the 2nd cluster fruit expnding stge, nd by 10.04, 10.92, 10.75, 1.91 nd 31.98% in the 4th cluster fruit expnding stge, nd by 18.27, 10.29, 10.90, 8.90 nd 25.99%, respectively in the lte growth stge. In comprison with CK, ReN2 leded to n verge of 40.39, 5.42 nd 10.63%, respectively, increse in minerl nitrogen of rhizosphere soil in 1st, 2nd nd 4th cluster fruit expnding stge (Tble1). Except for lte growth stge, the content of minerl nitrogen of rhizosphere soil decresed by 5.53%. The minerl nitrogen (N min) decrements in 0-10, 10-20, 20-30, 30-40, cm soil lyer of ReN1 were , 52.32, 17.58, 10.03, kg/hm 2, respectively (Fig.1). The Nmin decrements in 0-10, 10-20, 20-30, 30-40, cm soil lyer of ReN2 were , 44.71, 7.91, 14.45, kg/hm 2, respectively. The Nmin decrements in 0-10, 10-20, 20-30, 30-40, cm soil lyer of ReN3 were , 28.56, 3.00, 23.77, kg/hm 2, respectively. The Nmin decrements in 0-10, 10-20, 20-30, 30-40, cm soil lyer of ReN4 were , 35.08, 7.06, 22.19, kg/hm 2, respectively. The Nmin decrements in 0-10, 10-20, 20-30, 30-40, cm soil lyer of CK were , 26.39, 7.33, 18.04, kg/hm 2, respectively. After post-hrvest, residul minerl nitrogen in the 0-10, nd cm soil lyer of ReN2 ws significntly lower thn tht of CK, differing by 18.90, nd 10.11%, respectively (p < 0.001, Fig. 1). Except for cm nd cm soil lyer, the Nmin residul showed no significnt difference. Minerl nitrogen consumption in the 0-30 cm root soil lyer could be therefore used to evlute soil nitrogen for biologicl effectiveness nd root lyer nitrogen s supplying cpcity (Plese et l.

4 702 LI et l. 2009, Chen et l. 2012). Minerl nitrogen content of ReN2 nd ReN3 in the 0-30 cm root soil lyer ws mintined bove 40 mg/kg, which ws key evidence becuse nitrogen supplying cpcity under RMW irrigtion nd suitble topdressing (Zho et l. 2010). Post-hrvest minerl nitrogen residul in the nd cm lyers of ReN2 nd ReN3 ws significntly higher thn tht of ReN1 nd CK, however, totl nitrogen residul in the cm nd cm lyers of ReN1 ws significntly higher thn tht of ReN2 nd ReN3, which indicted tht nitrogen ccumultion in the lower soil ws coincident with the excessive ppliction of topdressing with RMW irrigtion. The growth of tomto cquired plenty of minerl nutrients tht cme minly from the rhizosphere soil (Pereir et l. 2011, Fonsec et l. 2005), however, the differences in minerl content between the rhizosphere nd bulk soil suggested tht the minerl nutrients of bulk soil migrted into the rhizosphere. Thus, the minerl nitrogen content between rhizosphere nd bulk soil were not significntly different during the tomto post-hrvest. Tble 2. Chnges of soil minerl nitrogen content of different growth stge under different topdressing mount of N with RMW nd tp wter irrigtion in the rhizosphere nd bulk soil. Soil division Tretments The 1st cluster expnding stge The content of minerl nitrogen (mg/kg) The 2nd cluster expnding stge The 4th cluster Lte growth stge expnding stge ReN ± 6.27 b ± cd ± 2.22 b ± 4.16 b ReN ± ± 7.06 bc ± 5.11 b ± 4.64 c Rhizosphere ReN ± 6.68 c ± 5.50 bc ± 1.98 b ± 1.64 c soil ReN ± 3.08 c ± 4.46 d ± 3.26 b ± 3.13 b CK ± 2.42 c ± 6.85 c ± 2.48 c ± 1.36 c ReN ± ± 3.27 b ± 5.76 b ± 3.03 ReN ± ± ± 2.83 b ± 6.06 bc Bulk ReN ± 5.90 bc ± b ± ± 2.42 bc soil ReN ± c ± 2.90 cd ± 1.56 b ± 1.70 b CK ± 3.16 bc ± 7.64 b ± ± 2.12 Different letters in the sme row indicte significnt differences (p < 0.05%) mong different tretments within soil division (Dt processing system 7.05 DMRT. The rhizosphere totl N content of ReN1, ReN2, ReN3, ReN4 nd CK ws higher thn tht of bulk soil by % in the 1st cluster fruit expnding stge, nd by % in the 2nd cluster, nd by % in the 4th cluster, nd by % in the lte growth stge. In comprison to CK, ReN2 leded to n verge of 7.27, 1.71 nd 2.83%, respectively increse in totl N in the 1st, 2nd nd 4th cluster fruit expnding stge in the rhizosphere soil lyer. Except for lte growth stge, the content of totl N of rhizosphere soil decresed by 3.85%. The totl N decrement in 0-10, 10-20, 20-30, 30-40, cm soil lyer of ReN1 ws , 95.09, 67.17, 61.81, kg/hm 2, respectively. The totl N decrement in 0-10, 10-20, 20-30, 30-40, cm soil lyer of ReN2 ws , 70.09, 41.77, nd 5.71 kg/hm 2, respectively. The totl N decrement in 0-10, 10-20, 20-30, 30-40, cm soil lyer of ReN3 ws , , 81.81, nd 7.71 kg/hm 2, respectively. The totl N decrement in

5 EFFECT OF RECLAIMED MUNICIPAL WASTEWATER IRRIGATION , 10-20, 20-30, 30-40, cm soil lyer of ReN4 ws , 36.96, , nd kg/hm 2, respectively. The totl N decrement in 0-10, 10-20, 20-30, 30-40, cm soil lyer of CK ws 84.80, 61.91, , , kg/hm 2, respectively (Fig. 2). In comprison to CK, residul TN in the 0-10, 10-20, 20-30, nd cm soil lyer of ReN2 showed no significnt difference fter post-hrvest. The totl N content of the rhizosphere in ll tretments ws higher thn tht of the bulk soil, which might be minly due to significntly higher quntity of microorgnisms in rhizosphere nd root exudtes (Hinsinger et l. 2009, Inselsbcher et l. 2010), furthermore, the totl N content of the rhizosphere nd bulk soil of ReN2 ws lower thn tht of CK, which might be minly due to significntly higher nitrogen utiliztion nd nitrogen priming effect by RMW irrigtion (Zhu et l. 2014, Chen et l. 2015). Nmin residul kg/hm b b b ReN1 ReN2 ReN3 ReN4 CK b bc b b b c Soil lyer depth cm Fig. 1. Residul Nmin of soil lyers under topdressing with RMW irrigtion fter post-hrvest. Different letters bove the brs indicte significnt differences (p < 0.05%) t the sme soil lyer depth mong different tretments (Dt processing system 7.05 DMRT. The number of rhizosphere microbil of ReN1, ReN2, ReN3, ReN4 nd CK ws significntly higher thn those of bulk soil in the 1st cluster, differing by 0.79, 0.40, 0.42, 0.53 nd 0.63-fold, 6.03, 7.80, 6.18, 4.65 nd 5.79-fold nd 0.85, 0.70, 0.24, 0.33 nd 0.25-fold in the 4th cluster, nd 6.46, 4.64, 3.82, 4.94 nd 3.17-fold, respectively in the lte growth stge (Tble 4). Microbil immobiliztion nd minerliztion tht occurred t the sme time were importnt prts of soil nitrogen cycle, rhizosphere minerl nitrogen ws consumed by microbil nd plnt roots, which further promoted the migrtion from bulk soil to the rhizosphere, thus, sufficient rhizosphere nutrient supply further boosted microbil growth nd incresed the mount of orgnic nitrogen (Inselsbcher et l. 2010). Nitrogen ws n importnt elementl constituent of ll orgnisms, nd soil nitrogen content influenced the microbil community composition. Nitrogen minerliztion nd immobiliztion ws closely relted to the bundnce of microorgnisms (Ros et l. 2007), the extent of rhizosphere microbil growth influenced the biologicl cycle, the re of root ctivities on soil nutrients, nd the microbil community composition (Fn et l. 2012). Root exudtes into the rhizosphere provided n bundnce of nutrients needed by microorgnisms (Lee et l. 2006, Hinsinger et l. 2009), thus, the quntity of rhizosphere microbil ws significntly higher thn tht of bulk soil. Compred to ReN2, ReN3 nd ReN4, the quntity of rhizosphere microbil in ReN1 ws significntly higher thn tht of ReN2, ReN3 nd ReN4. Furthermore, rhizosphere microbil ctivity promoted the process of minerl nitrogen immobiliztion (Chen et l. 2007), with

6 704 LI et l. decresed in rhizosphere minerl nitrogen, the migrtion of minerl nitrogen from bulk soil to the rhizosphere ws further stimulted (Lioussnne et l. 2010). The minerl nitrogen of ReN1 during the tomto growth stge ws lower thn tht of ReN2, which further confirmed the dynmic chnge of minerl nitrogen in the rhizosphere. Tble 3. Chnges of soil totl nitrogen content of different growth stges under different topdressing mount of N with RMW nd tp wter irrigtion in the rhizosphere nd bulk soil. The content of totl nitrogen (g/kg) Soil division Tretments The 1 st cluster expnding stge The 2 nd cluster expnding stge The 4 th cluster expnding stge Lte growth stge ReN ± ± ± ± 0.02 ReN ± 0.02 b 1.19 ± ± 0.03 b 1.00 ± 0.08 bc Rhizosphere ReN ± 0.06 bc 1.17 ± ± 0.10 b 1.02 ± 0.14 bc soil ReN ± 0.05 bc 1.17 ± ± 0.04 b 1.02 ± 0.06 bc CK 1.10 ± 0.03 bc 1.17 ± ± 0.05 b 1.04 ± 0.04 bc ReN ± 0.05 bc 1.16 ± ± 0.03 b 1.12 ± 0.05 b ReN ± 0.15 bc 1.07 ± ± 0.04 b 0.97 ± 0.04 c Bulk ReN ± 0.10 c 1.04 ± ± 0.10 b 0.98 ± 0.10 c soil ReN ± 0.11 c 1.04 ± ± 0.02 b 0.99 ± 0.02 c CK 0.96 ± 0.06 c 1.07 ± ± 0.06 b 1.00 ± 0.07 c Different letters in the sme row indicte significnt differences (p < 0.05%) mong different tretments within soil division (Dt processing system 7.05 DMRT. TN residul kg/hm ReN1 ReN2 ReN3 ReN4 CK Soil lyer depth cm Fig. 2. Residul totl N of soil lyers under topdressing with RMW irrigtion fter tomto hrvest. Different letters bove the brs indicte significnt differences (p < 0.05%) t the sme soil lyer depth mong different tretments (Dt processing system 7.05 DMRT).

7 EFFECT OF RECLAIMED MUNICIPAL WASTEWATER IRRIGATION 705 Tble 4. Chnges of soil microbil popultion t different growth stges of tomto in the rhizosphere nd bulk soils. Soil division Tretments The 1st cluster expnding stge Rhizosphere soil Bulk soil Microbil popultion10 4 CFU/g) The 2nd cluster expnding stge The 4th cluster expnding stge Lte growth stge ReN ± ± ± 1.00 b ± 9.17 ReN ± 6.25 b ± 8.81 b ± ± 6.81 b ReN ± 4.93 b ± 1.00 c ± 5.35 b ± 4.16 c ReN ± 3.06 c ± 0.50 d ± 1.53 c ± 4.73 c CK ± 1.73 c ± 4.35 c ± 0.73 c ± 1.52 c ReN ± 2.52 ef ± 1.76 e ± 2.08 f ± 3.51 d ReN ± 3.06 d ± 2.65 f ± 1.50 e ± 1.00 d ReN ± 3.06 de ± 1.53 f ± 3.06 d ± 2.00 e ReN ± 2.00 fg ± 1.44 f ± 2.00 e ± 1.00 e CK ± 3.84 g ± 1.04 f ± 1.35 e ± 1.00 e Different letters in the sme row indicte significnt differences (p < 0.05%) mong different tretments within soil division (Dt processing system 7.05 DMRT. The tomto yields of ReN1, ReN2, ReN3, ReN4 nd CK were , , , nd t/hm 2, respectively (Tble 5). The biomss of ReN2 ws significntly higher thn tht of CK differing by 8.66%, but significntly lower thn tht of ReN1 differing by 11.08%. The tomto yield of ReN2 ws significntly higher thn tht of ReN1, ReN3, ReN4 nd CK differing by 9.91, 4.74, 9.20 nd 9.38%, respectively. The nitrogen in plnt nd fruit of ReN2 ws significntly higher thn tht of ReN3, ReN4 nd CK differing by 46.62, nd 62.51%, respectively. Prtil fctor productivity from pplied N of ReN2 ws significntly higher thn tht of ReN1 nd CK differing by nd 20.59%, respectively. Apprent nitrogen loss of ReN2 ws significntly less thn tht of ReN1 nd CK differing by nd 6.34%, respectively. Nitrogen supplying cpcity of ReN1, ReN2 nd ReN3 were not significntly different but nitrogen supplying cpcity of ReN1, ReN2 nd ReN3 were significntly higher thn tht of ReN4 nd CK differing from 6.82 to 11.68%. Compring to CK, biomss, yield nd nitrogen in fruit of RMW irrigtion with suitble topdressing N tretment were significntly improved, resulting in higher prtil fctor productivity from pplied N nd nitrogen supplying cpcity. The tomto plnt biomss of ReN1 ws significntly higher thn tht of ReN2 nd ReN3, however, the ReN1 tretment resulted n incresed growth of the tomto plnts t the expense of tomto yield (Zhu et l. 2004). Thus, the yield of ReN2 nd ReN3 ws significntly higher thn tht of ReN1. Furthermore, prtil fctor productivity from pplied N for ReN2 nd ReN3 ws improved when compred with ReN1, nd nitrogen pprent loss for ReN2 nd ReN3 ws decresed (Eli et l. 2012). Obviously, the increse in tomto yield nd improvement in the nitrogen supplying cpcity of root lyer could be chieved by reducing the topdressing pplied N long with RMW irrigtion. The slinity of RMW could influence the soil cpcity for sustinble production fter long-term irrigtion (Xu et l. 2010, Plcios-Díz et l. 2009), further reserch ws needed to estblish this effect on the root lyer nitrogen supply cpcity.

8 706 LI et l. Tble 5. Tomto biomss, yield nd soil nitrogen supplying cpcity under different topdressing with RMW irrigtion. Tretments Nitrogen rte/(kg/hm 2 ) Bse Topdres fertilizer sing Nitrogen in Biomss irrigtion wter (t/hm 2 ) (kg/hm 2 ) Yield (t/hm 2 ) Nitrogen in plnt nd fruit (kg/hm 2 ) Nitrogen in fruit (kg/hm 2 ) PFP (kg/kg) NAL (kg/hm 2 ) NSC (kg/hm 2 ) ReN c c ReN bc b c ReN b b b 29.43b b c ReN c bc c 23.56d d b CK d c c 26.56c c b b Vlues followed by different letters of the sme column show significnt differences (p < 0.05) mong tretments, PFP from pplied N PFP = Tomto yield/nitrogen rte (kg/kg), NAL = N min residul of 0 to 30 cm root lyer before the tomto trnsplnt + bse fertilizer + topdressing + nitrogen in irrigtion wter-nitrogen in plnt nd fruit - Nmin residul of 0 to 30 cm root lyer fter the tomto post-hrvest. Nitrogen supplying cpcity (NSC) = Nmin vrition of 0 to 30 cm soil depth. A field experiment ws conducted in Xinxing city, Henn province, Chin to evlute the effects of reclimed wter irrigtion with topdressing N on soil nitrogen supplying cpcity of greenhouse soils. Our min findings re: (1) Reclimed wter irrigtion led to n verge of %, increse in minerl nitrogen of rhizosphere soil in 1st, 2nd nd 4th cluster fruit expnding stge, nd then n verge of %, increse in totl N of rhizosphere soil in 1st, 2nd nd 4th cluster fruit expnding stge. (2) RMW irrigtion could significntly increse the microbil popultion of rhizosphere soil in the tomto growth stge. The verge rhizosphere microbil popultion ws significntly incresed by bout 1.64-fold in the key growth stge. (3) RMW irrigtion could significntly improve the biomss nd yield of tomto, nd then the nitrogen in fruit, prtil fctor productivity from pplied N nd nitrogen supplying cpcity. The biomss nd yield were significntly incresed by 8.66 nd 9.38%, respectively. Furthermore, the nitrogen in fruit nd prtil fctor productivity from pplied N were significntly improved by nd 6.34%, respectively. (4) RMW irrigtion could significntly improve nitrogen supplying cpcity nd reduce the mount of topdressing N. The nitrogen supplying cpcity ws significntly improved by 8.38%. The mount of topdressing N decresed by 20-30% under RMW irrigtion. Acknowledgements The uthors re grteful for finncil support from the Ntionl Nturl Science Foundtion of Chin ( , , ), the Ntionl 863 Plns Project of Chin (863 Progrm, 2012 AA101404), nd the Specil Fund for Agro-scientific Reserch in the Public Interest ( ) for this study. References Chen YM, Wng MK, Zhung SY nd Ching PN Chemicl nd physicl properties of rhizosphere nd bulk soils of three te plnts cultivted in Ultisols. Geoderm 136(1-2): Chen XY, Liu MQ, Hu F, Mo XF nd Li HX Contributions of soil micro-fun (protozo nd nemtodes) to rhizosphere ecologicl functions. Act Ecol. Sinic 27(8):

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