Abstract:

【Objective】 The objective of this study was to investigate the characteristics of soil total organic carbon, labile organic carbon and carbon pool management index under non-flooded rice cultivation with straw mulching, and no-tillage and non-flooded rice cultivation with straw mulching. 【Method】 A field experiment was conducted since 2003 in double-rice cropping system in the Rice Yuanzhong Farm in Yujiang County, Jiangxi Province in southeast China. Soil samples at 0-15 cm depth were collected at the late-season rice harvest period in 2007, and contents of soil total organic carbon and different fractions of labile organic carbon under different rice cultivations were determined. The rice cultivations included conventional flooded rice cultivation (CF), non-flooded rice cultivation with zero straw mulching (ZM), non-flooded rice cultivation with straw mulching (SM), no-tillage and non-flooded rice cultivation with zero straw mulching (N-ZM), and no-tillage and non-flooded rice cultivation with straw mulching (N-SM). 【Result】 Compared with CF, SM and N-SM could significantly increase soil total organic carbon content, particulate organic carbon (53-2 000 μm) content, hot water-extractable organic carbon content, readily oxidizable organic carbon (oxidized by 333 mmol?L-1 KMnO4) content, and the percentage of labile organic carbon to soil total organic carbon, and soil organic carbon pool management index (CPMI). However, ZM could significantly decrease the parameters mentioned above compared to CF.【Conclusion】 As a novel water-saving technique and straw management, SM and N-SM applied to late-season rice cropping system might be an alternative to CF for improving and increasing soil fertility under double-rice cropping system, in the seasonal drought region of southeast China.

Key words: non-flooded rice cultivation, straw mulching, no-tillage, soil labile organic carbon, carbon pool management index