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Fate of fertilizer nitrogen and residual nitrogen in paddy soil in Northeast China

Journal of Integrative Agriculture 2023年第11期22卷 3535-3548页

作者： BI Shi-ting LUO Xiang-yu ZHANG Chen LI Peng-fei YU Cai-lian LIU Zhi-lei PENG Xian-long College of Agricultural Resources and Environmental Sciences Northeast Agricultural UniversityHarbin 150030P.R.China Key Laboratory of Germplasm Enhancement Physiology and Ecology of Food Crops in Cold Region of Ministry of EducationNortheast Agricultural UniversityHarbin 150030P.R.China The School of Material Science and Chemical Engineering Harbin University of Science and TechnologyHarbin 150080P.R.China

The relationship between the fate of nitrogen (N) fertilizer and the N application rate in paddy fields in Northeast China is unclear,as is the fate of residual N.To clarify these issues,paddy field and15N microplot experiments were carried out in 2017 and 2018,with N applications at five levels:0,75,105,135 and 165 kg N ha–1(N0,N75,N105,N135 and N165,respectively).15N-labeled urea was applied to the microplots in 2017,and the same amount of unlabeled urea was applied in 2018.Ammonia (NH3) volatilization,leaching,surface runoff,rice yield,the N contents and15N abundances of both plants and soil were analyzed.The results indicated a linear platform model for rice yield and the application rate of N fertilizer,and the optimal rate was 135 kg N ha–1.N uptake increased with an increasing N rate,and the recovery efficiency of applied N (REN) values of the difference subtraction method were 45.23 and 56.98%on average in 2017and 2018,respectively.The RENwas the highest at the N rate of 135 kg ha–1in 2017 and it was insignificantly affected by the N application rate in 2018,while the agronomic efficiency of applied N (AEN) and physiological efficiency of applied N (PEN) decreased significantly when excessive N was applied.N loss through NH3volatilization,leaching and surface runoff was low in the paddy fields in Northeast China.NH3volatilization accounted for 0.81 and 2.99%of the total N application in 2017 and 2018,respectively.On average,the leaching and surface runoff rates were 4.45% and less than 1.05%,respectively,but the apparent denitrification loss was approximately 42.63%.The residual N fertilizer in the soil layer (0–40 cm) was 18.37–31.81 kg N ha–1in 2017,and the residual rate was 19.28–24.50%.residual15N from fertilizer in the soil increased significantly with increasing N fertilizer,which was mainly concentrated in the 0–10 cm soil layer,accounting for 58.45–83.54% of the total residual N,and decreased with increasing depth.While the ratio of residual N in the 0–10 cm soil layer to that in the 0–40 cm soil

关键词： fate of N fertilizer NH_(3) volatilization leaching surface runoff residual nitrogen yield

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Origin,characteristics,and suppression of residual nitrogen in MPCVD diamond growth reactor

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Chinese Physics B 2022年第12期31卷 606-611页

作者：滕妍刘东阳汤琨赵伟康陈子昂黄颖蒙段晶晶卞岳叶建东朱顺明张荣郑有炓顾书林 School of Electronic Science and Engineering Nanjing UniversityNanjing 210046China

Unintentional nitrogen incorporation has been observed in a set of microwave plasma chemical vapor deposition(MPCVD)-grown samples.No abnormality has been detected on the apparatus especially the base pressure and feeding gas purity.By a comprehensive investigation including the analysis of the plasma composition,we found that a minor leakage of the system could be significantly magnified by the thermal effect,resulting in a considerable residual nitrogen in the diamond material.Moreover,the doping mechanism of leaked air is different to pure nitrogen doping.The dosage of several ppm of pure nitrogen can lead to efficient nitrogen incorporation in diamond,while at least thousands ppm of leaked air is required for detecting obvious residual nitrogen.The difference of the dosage has been ascribed to the suppression effect of oxygen that consumes nitrogen.As the unintentional impurity is basically detrimental to the controllable fabrication of diamond for electronic application,we have provided an effective way to suppress the residual nitrogen in a slightly leaked system by modifying the susceptor geometry.This study indicates that even if a normal base pressure can be reached,the nitrogen residing in the chamber can be“activated”by the thermal effect and thus be incorporated in diamond material grown by a MPCVD reactor.

关键词： microwave plasma chemical vapor deposition diamond residual nitrogen system leakage

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Significant suppression of residual nitrogen incorporation in diamond film with a novel susceptor geometry employed in MPCVD

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Chinese Physics B 2022年第11期31卷 593-598页

作者：赵伟康滕妍汤琨朱顺明杨凯段晶晶黄颖蒙陈子昂叶建东顾书林 School of Electronic Science&Engineering Nanjing UniversityNanjing 210046China

This work proposed to change the structure of the sample susceptor of the microwave plasma chemical vapor deposition(MPCVD)reaction chamber,that is,to introduce a small hole in the center of the susceptor to study its suppression effect on the incorporation of residual nitrogen in the MPCVD diamond film.By using COMSOL multiphysics software simulation,the plasma characteristics and the concentration of chemical reactants in the cylindrical cavity of MPCVD system were studied,including electric field intensity,electron number density,electron temperature,the concentrations of atomic hydrogen,methyl,and nitrogenous substances,etc.After introducing a small hole in the center of the molybdenum support susceptor,we found that no significant changes were found in the center area of the plasma,but the electron state in the plasma changed greatly on the surface above the susceptor.The electron number density was reduced by about 40%,while the electron temperature was reduced by about 0.02 eV,and the concentration of atomic nitrogen was decreased by about an order of magnitude.Moreover,we found that if a specific lower microwave input power is used,and a susceptor structure without the small hole is introduced,the change results similar to those in the surface area of the susceptor will be obtained,but the spatial distribution of electromagnetic field and reactant concentration will be changed.

关键词： plasma simulation diamond microwave plasma chemical vapor deposition(MPCVD) residual nitrogen

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Effects of nitrogen supply methods on fate of nitrogen in maize under alternate partial root-zone irrigation

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International Journal of Agricultural and Biological Engineering 2020年第3期13卷 129-135页

作者： Dongliang Qi Tiantian Hu Xue Song Engineering Research Center of Ecology and Agriculture Use of Wetland Ministry of EducationYangtze UniversityJingzhou 434025HubeiChina Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas of Ministry of Education Northwest A&F UniversityYangling 712100ShaanxiChina

Partial root-zone irrigation(PRI)has been practiced worldwide,but little information is available on nitrogen(N)supply methods influence on fate of applied N fertilizer for crop production under PRI.A field experiment was conducted to investigate effect of N supply methods on the uptake,residual,and loss of applied N fertilizer in maize(Zea mays L.)under alternate PRI at Wuwei,northwest China in 2014.15N-labeled urea was used as N fertilizer.Two irrigation methods included alternate furrow irrigation(AI)and conventional furrow irrigation(CI).Two N fertilizer supply methods included conventional N supply(CN)and alternate N supply(AN),were applied in combination with each irrigation method.Grain yield,root length density(RLD),N uptake by maize at the maturity stage,and atom%of 15N excess,residual 15N and residual NO3-N in the 0-100 cm soil layer after maize harvest were determined.Results shown that compared to CI coupled with CN,AI coupled with AN or CN significantly increased the grain yield,harvest index,RLD,N uptake by maize,15N accumulation in grain,atom%of 15N excess in the 0-60 cm soil layer,the residual 15N and 15N uptake rates;but significantly decreased the residual NO3-N in the 0-100 cm soil layers and 15N loss rate.Moreover,the synchronized rather than separation supply of N fertilizer and water enhanced the most above parameters under AI.15N uptake rate was positively correlated with RLD in the 0-40 cm soil layer,suggesting that the enhanced RLD contributed to the improved 15N uptake rate.Therefore,alternate furrow irrigation coupled with conventional or alternate nitrogen supply(synchronized supply of N fertilizer and water)could help improve 15N uptake rate and reduce the 15N loss rate.

关键词： 15N-labeled technology root length density nitrogen fertilizer fate nitrogen management residual nitrogen

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