[Effects of Water and Nitrogenous Fertilizer Coupling on CH4 and N2O Emission from Double-Season Rice Paddy Field].

To provide support for the efficient use of water and fertilizer technology to double-season rice cultivation, water and fertilizer coupling mode was applied in this research, including two irrigation methods and four N levels. The irrigation methods were flood irrigation and intermittent irrigation, while four N levels were high-N, middle-N, low-N and none-N. Field experiment was conducted to study the effect of water and fertilizer coupling mode on CH4 and N2O emission. The results showed that the accumulated CH4 emissions were significantly reduced by intermittent irrigation, in comparison with flood irrigation, the reduction in early rice season were from 13. 18 kg.hm-2 to 87. 90 kg.hm-2, and were from 74. 48 kg.hm-2 to 131. 07 kg.hm-2 in late rice season, with a rate of 24. 4% -67. 4% and 42. 5% -65. 5% respectively; whereas the accumulated N20 emissions were increased, the increment were from 0. 03 kg.hm-2 to 0. 24 kg.hm-2 in early rice season and from 0. 35 kg.hm-2 to 1. 53 kg.hm-2 in late rice season when compared flood irrigation, increased by 6.2% -18. 3% and 40.2% - 80.9% respectively. On the whole, intermittent irrigation reduces the warming potential of greenhouse gases (GWP), which were decreased by 18. 8% to 58. 6% in early rice season and by 34. 4% to 60. 1% in late rice season, and the reduction of total GWP were from 2 388 to 4 151 kg. hm-2 (CO2 eq), with a rate of 41% -54% . Through correlation analysis it found that CH4 emissions from soil were significantly related with soil solution Eh and solution CH4 concentration. In comparison with the flood irrigation, the application of intermittent irrigation in double-season rice cultivation was conducive to CH4 reduction, though the increase came in N2O, but the GWPs were significantly reduced. Comprehensively, intermittent irrigation matching with middle-N is more benefit to double-season rice cultivation.