覆草旱作对稻田土壤活性有机碳的影响

Soil Labile Organic Carbon as Affected by Non-flooded Rice Cultivation with Straw Mulching Under Different Tillages

【目的】研究覆草旱作和免耕覆草旱作稻田土壤总有机碳、活性有机碳含量和碳库管理指数的特征。【方法】在江西省余江县水稻原种场的双季稻田,设置常规水作、裸地旱作、覆草旱作、免耕裸地旱作和免耕覆草旱作5个处理。于第5年晚稻收获期,采集以上处理的耕层土壤样品,测定了土壤总有机碳和活性有机碳含量。【结果】与常规水作相比,覆草旱作和免耕覆草旱作显著提高稻田土壤总有机碳、颗粒有机碳、热水提取有机碳和易氧化态有机碳含量,以及各组分活性有机碳的分配比例,且土壤碳库管理指数显著提高。而裸地旱作较常规水作上述指标显著降低。【结论】在中国南方季节性干旱区双季稻轮作系统上,覆草旱作和免耕覆草旱作较常规水作明显提高稻田土壤肥力。

[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 grn） content, hot water-extractable organic carbon content, readily oxidizable organic carbon （oxidized by 333 mmol-L1 KMnO,） 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.