Effect of nitrogen fertilizer application on greenhouse gas emissions fromsoil in paddy field

Abstract: Abstract: Paddy fields is the main source of global greenhouse gas emission, and different nitrogen application levels may impact greenhouse gas emissions. The research object is late rice in Jiangxi double cropping rice field, and the treatments include 4 different nitrogen fertilizer levels: control with no nitrogen (N0), nitrogen reduction by 40% (N1), conventional nitrogen (N2), and nitrogen adding by 50% (N3). The emissions and emission rate of nitrous oxide (N2O), methane (CH4) and carbon dioxide (CO2) were studied by using static chamber - gas chromatograph, and we also computed the global warming potential (GWP) and greenhouse gas intensity (GHGI). The results of the study showed that in the process of late rice growth, the emission flux of N2O and CO2 presented 3 high peaks and all showed that adding nitrogen treatment was higher than other treatments, but the emission flux of CH4 only had a peak. The emissions of N2O under the treatments of N0, N1 and N2 did not have significant difference (P>0.05), only when the nitrogen application amount achieved the maximum value (N3 treatment), the N2O emissions were significantly higher than other treatments. Compared with the N0, the total emissions of CH4 under other 3 treatments (N1, N2 and N3 ) increased by 58.70%, 69.63% and 96.15% respectively, and the GWP increased by 22.34%, 25.34% and 52.92% separately. The GHGI of the N3 was the highest, up to 1.12 kg/kg, and it was significantly higher than N1 and N2. Compared with the conventional fertilizer application, reducing 40% nitrogen fertilizer had no significant effect on rice yield, but it could reduce the total amount of CO2 and CH4, which was beneficial to the energy saving and emission reduction.