Effects of nitrogen application and maize growth on N2O emission from soil

Using the pot experiment and closed static chamber-gas chromatography (GC) technique, this paper studied the effects of nitrogen application (150 and 300 mg/kg soil) and maize growth on N2O emission from soil. In maize-planted soil, the N2O emission rate increased with increasing N application rate, its peak appeared at the seedling stage, and there was no significant correlation between N2O emission rate and air temperature. Contrarily, in exposed soil, the peak of N2O emission rate occurred at the later stages of the experiment, and there was a significant exponential correlation between soil N2O emission rate and air temperature, in which Q 10 (the value of soil N2O emission rate responding to temperature) was 4.4 and 3.2 in high and low N applications. The total amount of N2O emission increased remarkably with increased N application rate in both planted and un-planted soils. N2O emission inventory from exposed and maize-planted soils in high N application was 2.5 and 1.6 times as high as that in low N application, respectively. In the same N application rate, N2O emission inventory in high and low N application from exposed soil was 12 and 7.5 times as high as that from maize-planted soil, respectively. As compared with exposed soil, maize growth reduced N2O emission by 92% and 87%, respectively, at high and low N application rates. In summary, maize growth and nitrogen application not only affected the seasonal variation and magnitude of N2O emission from soil, but also altered the relationship between air temperature and soil N2O emission.