Gaseous losses of nitrogen by ammonia volatilization and nitrous oxide emissions from rice paddies with different irrigation management

To reveal the influence of non-flooding controlled irrigation (NFI) on gaseous nitrogen (N) losses in forms of ammonia volatilization (AV) and nitrous oxide (N2O) emissions from high N inputs rice paddies, lysimeter experiments were conducted with flooding irrigation (FI) as check. Compared with FI paddies, AV losses in NFI paddies decreased by 18.5-20.5 % and N2O emissions increased by 1.43-1.9 kg N ha(-1). Weekly AV losses immediately after fertilization accounted for over 83 % of seasonal losses in both treatments. High N2O emissions from NFI paddies always occurred in drying process after N application, with peaks observed when water-filled pore space (WFPS) fell in 75-85 %. Water management immediately after N fertilization is crucial for mitigating gaseous N losses from rice paddies. Bringing N into shallow rhizosphere by irrigation and covering it with deep water will be helpful in preventing AV. Maintaining a flooding period and keeping WFPS higher than 85 % in the first drying process after fertilization might be effective to reduce N2O emissions peaks for NFI paddies.