College of Resources & Environmental Sciences, Nanjing Agricultural University, Nanjing 210095, PR China.
Sci Total Environ. 2010 Jan 15;408(4):906-13. doi: 10.1016/j.scitotenv.2009.11.002. Epub 2009 Nov 18.
Annual paddy rice-winter wheat rotation constitutes one of the typical cropping systems in southeast China, in which various water regimes are currently practiced during the rice-growing season, including continuous flooding (F), flooding-midseason drainage-reflooding (F-D-F), and flooding-midseason drainage-reflooding and moisture but without waterlogging (F-D-F-M). We conducted a field experiment in a rice-winter wheat rotation system to gain an insight into the water regime-specific emission factors and background emissions of nitrous oxide (N(2)O) over the whole annual cycle. While flooding led to an unpronounced N(2)O emission during the rice-growing season, it incurred substantial N(2)O emission during the following non-rice season. During the non-rice season, N(2)O fluxes were, on average, 2.61 and 2.48 mg N(2)O-Nm(-)(2) day(-1) for the 250 kg N ha(-1) applied plots preceded by the F and F-D-F water regimes, which are 56% and 49% higher than those by the F-D-F-M water regime, respectively. For the annual rotation system experienced by continuous flooding during the rice-growing season, the relationship between N(2)O emission and nitrogen input predicted the emission factor and background emission of N(2)O to be 0.87% and 1.77 kg N(2)O-Nha(-1), respectively. For the plots experienced by the water regimes of F-D-F and F-D-F-M, the emission factors of N(2)O averaged 0.97% and 0.85%, with background N(2)O emissions of 2.00 kg N(2)O-Nha(-1) and 1.61 kg N(2)O-Nha(-1) for the annual rotation system, respectively. Annual direct N(2)O-N emission was estimated to be 98.1 Gg yr(-1) in Chinese rice-based cropping systems in the 1990s, consisting of 32.3 Gg during the rice-growing season and 65.8 Gg during the non-rice season, which accounts for 25-35% of the annual total emission from croplands in China.
在中国东南部，水稻-冬小麦轮作是典型的种植制度之一，目前在水稻生长期实行各种水分管理制度，包括连续淹水（F）、淹水-中期排水-再淹水（F-D-F）和淹水-中期排水-再淹水和湿润但无渍水（F-D-F-M）。我们在水稻-冬小麦轮作系统中进行了田间试验，以深入了解整个年度周期中特定水分管理制度下氧化亚氮（N2O）排放因子和背景排放。虽然淹水在水稻生长期导致 N2O 排放不明显，但在随后的非水稻季节会产生大量的 N2O 排放。在非水稻季节，施加 250kg N/ha 的处理中，F 和 F-D-F 水分管理制度下的 N2O 通量平均分别为 2.61 和 2.48mg N2O-N/m-2/d-1，分别比 F-D-F-M 水分管理制度高 56%和 49%。对于连续淹水的水稻生长期的轮作系统，N2O 排放与氮输入的关系预测 N2O 排放因子和背景排放分别为 0.87%和 1.77kg N2O-N/ha-1。对于经历 F-D-F 和 F-D-F-M 水分管理制度的处理，N2O 排放因子平均为 0.97%和 0.85%，轮作系统的背景 N2O 排放分别为 2.00kg N2O-N/ha-1 和 1.61kg N2O-N/ha-1。1990 年代，中国基于水稻的种植系统中，每年直接 N2O-N 排放量估计为 98.1 Gg yr-1，其中 32.3 Gg 在水稻生长期，65.8 Gg 在非水稻生长期，占中国农田年总排放量的 25-35%。
