Effect of different conservational tillage modes on the oxidation stability of soil organic carbon in soil micro-aggregates | 不同保护性耕作方式对微团聚体有机碳氧化稳定性的影响

Chinese. 探讨保护性耕作措施对土壤微团聚体有机碳含量及其氧化稳定性的影响。以关中平原历时7年、不同耕作方式（深松、旋耕、免耕、秸秆还田+传统耕作、传统耕作）的定位试验田为研究对象，于2008-10玉米收获后采集耕层（0～20 cm）土样，测定了全土及0.05~0.25 mm，0.01~0.05 mm，0.01 mm土壤微团聚体中总有机碳、易氧化有机碳和难氧化有机碳含量，并对其相关性进行了分析。与传统耕作比较，深松和旋耕提高了土壤总有机碳含量，降低了有机碳的氧化稳定性，而免耕和秸秆还田+传统耕作对土壤总有机碳含量及氧化稳定性的影响较小。旋耕和深松使土壤总有机碳、易氧化有机碳、难氧化有机碳含量在0.05~0.25 mm和0.01~0.05 mm微团聚体中显著增加，而在0.01 mm微团聚体中有所降低；深松和旋耕对微团聚体有机碳氧化稳定性的影响未达到显著水平，免耕明显降低了各粒级微团聚体有机碳的氧化稳定性。相关分析表明，总有机碳、易氧化有机碳含量在全土和0.05~0.25 mm，0.01~0.05 mm微团聚体之间呈极显著相关关系，而与0.01 mm微团聚体之间无相关关系。土娄土总有机碳含量和氧化稳定性主要取决于0.05~0.25 mm微团聚体，深松、旋耕有利于总有机碳含量的积累及有机碳氧化稳定性的降低。

English. The research was conducted in order to study the effect of conservational tillage measures on the oxidation stability of organic carbon in soil micro-aggregates. A seven-year -location experiment of different tillage modes (sub-soiling, rotary tillage, no-tillage, conventional tillage with straw return and conventional tillage) in Guanzhong plain was conducted. The soil samples of top layer (0－20 cm) were collected after the corn had been harvested in October 2008. The content of total organic carbon, readily oxidizable organic carbon and difficultly oxidizable organic carbon in total soil and in 0.05－0.25 mm, 0.01－0.05 mm, 0.01 mm micro-aggregates were measured, and the correlation between-them also was analyzed. Compared with conventional tillage, sub-soiling, rotary tillage increased the content of soil organic carbon, decreased the oxidation stability of soil organic carbon; But, no-tillage and conventional tillage with straw incorporated had little effects on the content and oxidation stability of soil organic carbon. sub-soiling and rotary tillage increased significantly the content of total organic carbon, readily oxidizable organic carbon and difficultly oxidizable organic carbon in 0.05－0.25 mm and 0.01－0.05 mm micro-aggregates, but decreased the content of them in 0.01 mm soil micro-aggregates. The effects of sub-soiling and rotary tillage on the oxidation stability of soil organic carbon in micro-aggregates were insignificant. No-tillage decreased significantly the oxidation stability of soil organic carbon in micro-aggregates, the correlation analysis demonstrated that soil organic carbon, readily oxidizable organic carbon in total soil were significantly correlated with them in 0.05－0.25 mm and 0.01－0.05 mm micro-aggregates, not correlated with them in 0.01 mm soil micro-aggregates. The content and the oxidation stability of soil organic carbon in Lou soil mainly depended on the 0.05－0.25 mm micro-aggregates. Rotary tillage, sub-soiling could increase the content of soil organic carbon and decrease the oxidation stability of soil organic carbon.