Effects of nitrogen fertilizer management on greenhouse gas emissions from maize field in black soil

Greenhouse gas (GHG) emission from agricultural production is an important source of atmospheric GHG. It is crucial to explore corresponding measures and their effect on mitigating GHG emissions. To gain high crop yield without increasing GHG emissions, it is necessary to propose new nitrogen (N) fertilizer management strategies. This study was conducted to determine the effects of different nitrogen fertilizer management (conventional fertilization, decreasing within 20% of the conventional N application rate, nitrification inhibitor and controlled release fertilizer) on greenhouse gases emissions from spring maize field in black soil using the static chamber-gas chromatograph method. The results showed that: the peak of N2O emission flux occurred within 1~3 days after basal fertilization and top-dressing from maize field in black soil. 28.8%~41.9% of total N2O emissions during maize growth period were emitted within the first 16days after basal fertilization and top-dressing. Decreasing within 20% of the conventional N application rate significantly decreased the total N2O emissions. Compared with the conventional fertilization with higher rates of N fertilizer (185 kg N/ha), the total N2O emissions and annual global warming potential (GWP) were decreased by 17.6%~46.1% and 30.7%~67.8% respectively under improved N management practices, whereas greenhouse gas intensity (GHGI) were decreased by 29.1%~67.0%. Nitrification inhibitor addition showed the lowest total N2O emissions, GWP and GHGI compared with other treatments. Higher CO2 emission fluxes occurred from elongating to milky-riping stage. The maize field was a weak sink of atmospheric CH4 in black soil. The emission fluxes of CO2 and CH4 were not affected by N application rate (148~185 kg N/hm2) and nitrification inhibitor, respectively. Nitrification inhibitor and controlled release fertilizer had no significant influence on the yield of maize. Under the conditions of our experiment, decreasing N rate by 20% at the basic level of 185 kg N/hm2 combined with nitrification inhibitor can maintain the stable yield of maize, therefore could be served as an appropriate practice for mitigating GHG emissions with reduction of cost in black soil area. ©, 2015, Chinese Society for Environmental Sciences. All right reserved.