Modeling the impacts of alternative fertilization methods on nitrogen loading in rice production in Shanghai.
Nitrogen (N) loss from paddy fields is an important source of agricultural non-point source pollution that leads to eutrophication of water bodies and degradation of water quality. The impacts of alternative N fertilizer management practices on N loading (N loss through runoff and leaching) from paddy fields in Shanghai were assessed using a process-based biogeochemical model, DNDC. The results indicated that the current fertilization rate in paddy fields of Shanghai (300kgN/ha) exceeds the actual rice demand and has led to substantial N loading of 1142±276kg. The combined application of urea at 150kgN/ha and organic manure at 100kgN/ha was identified as the best fertilization method for rice cultivation in Shanghai; this application maintained optimal rice yields and significantly reduced N loading to 714±151kg in comparison with the current fertilization rate. A sensitivity test was conducted with various input parameters, and the results indicated that fertilization, precipitation and soil properties were the most sensitive factors that regulate N loss from paddy fields. The variability of soil properties, especially SOC led to high uncertainties in the simulated results. Therefore, the local climate conditions and soil properties should be taken into account in the identification of the best management practice (BMP) for rice cultivation, given the high spatially heterogeneous N loading values across all towns used in the simulation. The DNDC model is an effective approach for simulating and predicting N loading in paddy fields under alternative agricultural management practices.
School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China; Eco-environmental Protection Institute of Shanghai Academy of Agricultural Science, Shanghai 201403, China.
Zheng
Z
Zhao
School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
Zhimin
Z
Sha
Jiangsu Key Laboratory of Agricultural Meteorology, School of Applied Meteorology, Nanjing University of Information Science and Technology, Nanjing 210044, China; Institute for the Study of Earth, Ocean and Space, University of New Hampshire, Durham, NH 03824, USA.
Yibo
Y
Liu
Eco-environmental Protection Institute of Shanghai Academy of Agricultural Science, Shanghai 201403, China.
Shuhang
S
Wu
Eco-environmental Protection Institute of Shanghai Academy of Agricultural Science, Shanghai 201403, China.
Hanlin
H
Zhang
Institute for the Study of Earth, Ocean and Space, University of New Hampshire, Durham, NH 03824, USA.
Changsheng
C
Li
School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China.
Qi
Q
Zhao
School of Agriculture and Biology, Shanghai Jiao Tong University, Shanghai 200240, China. Electronic address: clk@sjtu.edu.cn.
Linkui
L
Cao
D002681:China; D004784:Environmental Monitoring; D005308:Fertilizers / Q000032:analysis*; D005618:Fresh Water / Q000032:analysis*; D008956:Models, Chemical; D009584:Nitrogen / Q000378:metabolism*; D012275:Oryza / Q000254:growth & development / Q000378:metabolism*; D014874:Water Pollutants, Chemical / Q000032:analysis*
D005308:Fertilizers; D014874:Water Pollutants, Chemical; D009584:Nitrogen
Best management practice; DNDC model; Nitrogen loading; Organic manure; Paddy field