基于APSIM模型不同水氮处理下N2O的排放研究

Modelling the Impact of Water and Nitrogen Application on NO Emission from Farmland Using the APSIM Model

【目的】探究关中平原冬小麦-夏玉米不同施氮量下不同生育期亏缺灌溉对冬小麦-夏玉米轮作体系N2O排放量及产量的影响,优化水氮管理措施。【方法】通过2016年10月—2018年10月田间试验,得到不同亏缺灌溉处理下作物产量、土壤水分和N2O排放量数据;并利用得到的数据对农田生态系统管理模型(APSIM)进行调参,使用验证后的APSIM模型模拟不同施氮水平N50(50 kg/hm2)、N100(100 kg/hm2)、N150(150 kg/hm2)、N200(200 kg/hm2)、N250(250 kg/hm2)、N300(300 kg/hm2)和不同水分处理CK(充分灌水)、T1(苗期和拔节期重度亏水)、T2(苗期重度亏水、拔节期中度亏水)、T3(苗期重度亏水、灌浆期中度亏水)、T4(苗期和拔节期中度亏水)、T5(苗期和灌浆期中度亏水)下,作物产量、N2O排放量、N2O气体排放强度和水分利用效率变化特征。【结果】APSIM模型可以很好的模拟不同水分处理下作物生长发育,随着施氮量的增加,各水分处理N2O排放量均呈上升趋势,施氮量为150 kg/hm2时,每季轮作总产量最大。当施氮水平高于200 kg/hm2时,苗期重度亏水的T1和T2处理N2O排放量显著低于CK。当每季作物施氮量为150 kg/hm2时,整个轮作体系中在苗期和拔节期中度亏水的T4处理水分利用效率显著高于其他处理,为2.37 kg/m3,N2O排放强度则与T1处理之外的其他无显著差异。【结论】综合考虑冬小麦-夏玉米轮作体系经济和生态效应,每季作物施氮量以150 kg/hm2为最佳,水分处理则以在苗期和拔节期亏水的T4处理最佳。

【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 300kg/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 (2.37kg/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.