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| DOI：10.13522/j.cnki.ggps.2020036 |
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| Modelling the Impact of Water and Nitrogen Application on N2O Emission from Farmland Using the APSIM Model |
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MA Chenguang, CAI Huanjie , LU Yajun
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1.Institude of Water-saving Agriculture in Arid Areas of China, Northwest A&F University, Yangling 712100, China 2.College of Water Research and Architectural Engineering, Northwest A&F University, Yangling 712100, China 3.Key Laboratory of Agricultural Soil and Water Engineering in Arid and Semiarid Areas,Ministry of Education, Yangling 712100, China
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| Abstract: |
| 【Background】N2O emission from agricultural soils has been rising over the past decades due to the excessive application of nitrogen fertilizers in China, despite the decline in agricultural water consumption. Understanding the mechanisms underlying N2O emission and reducing it is an urgent task in developing sustainable agriculture.【Objective】 The purpose of this paper is to elucidate how water and nitrogen coupled at different levels and ratios affect N2O emission from winter wheat-maize rotation fields based on both experiment and modelling. 【Method】 The experiments were conducted in October 2016 and October 2018 under different nitrogen application and deficit irrigations at a field in Guanzhong, Shanxi province. In the experiments, we measured crop yields, soil moisture and N2O emissions and used these data to calibrate the Agricultural Production Systems Simulator model (APSIM). The calibrated parameters and model were then used to simulate the variation in crop yields, N2O emission and water use efficiency under a nitrogen application gradient varying from 50 kg/hm2 to 300 kg/hm2 and different deficit irrigations ranging from sufficient irrigation (CK), severe water deficit at seedling and jointing stages (T1), severe water deficit at seedling stage and moderate water deficit at jointing stage (T2), severe water deficit at seedling stage and moderate water deficit at grain filling stage (T3), moderate water deficit at seedling stage and jointing stage (T4), moderate water deficit at seedling stage and grain filling stage (T5). 【Result】The calibration showed that the APSIM accurately reproduced the crop growth and development under different water treatments, and that the N2O emission under different irrigations increased with nitrogen application. The maximum yield of the two rotated crops was when nitrogen application was 150 kg/hm2. When the nitrogen application exceeded 200 kg/hm2, the N2O emission from T1 and T2 treatment was significantly lower than that from the CK. When the nitrogen was applied at 150 kg/hm2 to each crop, T4 had the highest water use efficiency (2.37 kg/m3), while its associated N2O emission intensity did not differ from that in other treatments (except T1) at a significant level.【Conclusion】In terms of balancing the economic return and the ecological impact of the winter wheat-maize rotation system, applying nitrogen at 150 kg/hm2 to each crop and introducing water deficit at seedling and jointing stages is most optimal to reduce N2O emission without compromising the economic return. |
| Key words: deficit irrigation; nitrogen rate; APSIM model; N2O emission; yield |
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