Lowering nitrogen inputs and optimizing fertilizer types can reduce direct and indirect greenhouse gas emissions from rice-wheat rotation systems

Agriculture soil is one of major sources of greenhouse gas (GHG) emissions. A wise use of nitrogen (N) fertilizer is important for mitigating GHG emissions. To evaluate the potential of different fertilizers treatments to mitigate total GHG emissions, a field experiment was conducted to investigate nitrous oxide (N2O), methane (CH4) and ammonia (NH3) emissions and nitrate (NO3−) leaching from a typical rice and winter wheat rotation system in Southeast China. Six reduced N treatments (including single reducing N input, increasing potassium input, combined application of urea ammonium (UA) and organic fertilizer (OF), single application of urea with hydroquinone and dicyandiamide (UHD) and urea formaldehyde (UF)) and the local practice (conventional N fertilizer) were applied in the study. Most of the reduced N treatments tended to reduce the cumulative CH4, N2O and NH3 emissions and NO3− leaching relative to the local practice, while single application of UHD during the rice season obviously increased the CH4 and NH3 emissions (p