Simulation of the factors influencing N₂O emission in summer corn farmland

【Objectives】 Agricultural soils are considered as a major source of N2O emission contributing approximately 46%-52% of the global anthropogenic N2O flux. We analyzed the contribution of climate factors, nitrogen (N) fertilizer application rates and the absorption of summer corn on N2O emission from soil in summer corn field which had great importance to reduce N2O emissions produced by N fertilizer.【Methods】Split plot field experiments were conducted in summer corn in 2012 and 2013. The main factor was summer corn and fallow field, the deputy factor was nitrogen application rates (N 0, 150, 300, 450 kg/hm2). N2O emission rate was determined using static chamber technology combined with gas chromatography in different treatments. The contribution of temperature, precipitation, nitrogen managements and the absorption of summer corn on N2O emission was calculated.【Results】 The influence of meteorological conditions on the N2O emission was significant. The impact factors of temperature and precipitation on the N2O emission were -0.24 and -0.07 in 2012 and 2013, respectively. Nitrogen fertilization increased N2O emission which followed a linear relationship with the increase of N application rate (R2 = 0.923). The effect of nitrogen application on N2O emission was 0, 0.38, 1.63 and 3.54 when the N application rate was 0, 150, 300 and 450 kg/hm2, respectively. The average impact factor of summer corn growth on the N2O emission was -0.33, which did not differ between 2012 and 2013 (P = 0.07). At seedling stage, ear period and grain stage, the effect of summer corn growth on the N2O emission was -0.57, -0.29 and -0.13, respectively, and had significant difference between growing stages (P =0.0015). Climatic condition had no significant effect on N2O emission on summer corn field under different nitrogen application rates (P 0.05). With the different climates in years, there was no significant effect of summer corn growth on the N2O emission with different temperature and precipitation under the same nitrogen application rate (P 0.05).【Conclusions】 Higher temperature and precipitation greatly stimulate N2O. High nitrogen fertilization application leads to increased N2O emission. Summer corn growth has a negative impact on N2O emission, which varies significantly in different growing stages. Climate and crop absorption are the two main factors influencing N2O emission when the nitrogen application rate is less than 150 kg/hm2, and nitrogen application is the main factor when the nitrogen rate is higher than 300 kg/hm2.