Identify the optimization strategy of nitrogen fertilization level based on trade-off analysis between rice production and greenhouse gas emission

Application of nitrogen (N) fertilizer increases grain yield and soil organic carbon (SOC) sequestration, but accompanied by the emission of greenhouse gas (GHG) especially nitrous oxide (N2O). To spatial-temporally analyze the trade-off between yield and GHG emissions under different N fertilization levels at regional scale, this study integrated geographic information system (GIS) and the DeNitrification-DeComposition (DNDC, Version 9.5) model to define the impacts of different N fertilization levels on rice production, SOC sequestration, and GHG emission in Fuyang District, a county-scale region in Eastern China. The whole region was divided into 28825 polygon-based modeling units based on heterogeneity of soil property, climate and agricultural management conditions. After validating the DNDC model by field observation data of the year 1979 and 2015, five N fertilization levels (0, 140, 210, 280 and 350 kg N ha(-1)) from the year 2016-2035 were designed for simulating the rice yield, SOC sequestration, N2O and methane (CH4) emissions. Validation results showed a good performance of the refined DNDC model. Simulation results indicated that yield and GHG emission increased with the growth of N fertilization rate, but the SOC sequestration change was not noticeable. Around 210 kg N ha(-1) was recommended as optimal N fertilization level in Fuyang District, because its global warming potential intensity (GWPI) was the lowest among all the N fertilization levels. As excessive N input is a common problem across China, our results provide a case for a win-win scenario for both food security and environmental friendliness. (C) 2019 Published by Elsevier Ltd.