Methane emissions from double-rice cropping system under conventional and no tillage in southeast China

A field experiment was carried out to investigate the methane emission pattern in a double-rice cropping system under conventional and no tillage in southeast China. The treatments included conventional tillage cultivation in both early rice and late rice (T-T) and conventional tillage in early rice but no-till in late rice (T-NT). The maximum methane emission rate of T-T and T-NT was 21.71 mg m(-2) h(-1) and 24.70 mg m(-2) h(-1) in early rice, respectively; and 18.52 mg m(-2) h(-1) and 732 mg m(-2) h(-1) in late rice, respectively. The seasonal amount of methane emission from the T-T and T-NT was not significantly different in early rice, but significant different (P < 0.05) in late rice, with the values 6.57 g m(-2) and 3.04 g m(-2), respectively. In comparison with early rice, the seasonal amount methane flux of late rice was reduced by 29% and 68% in the T-T and T-NT, respectively. The decrease of methane emission in the T-NT was attributed to lower dissolved organic carbon (DOC) content and higher soil bulk density. In conclusion, no tillage practice conducted in rice cropping season will markedly decrease methane emission for the rice cropping system. (C) 2011 Elsevier B.V. All rights reserved.