不同退耕模式下土壤水稳性团聚体及其有机碳分布特征

Distribution Characteristics and Soil Organic Carbon of Soil Water-Stable Aggregates with Different De-Farming Patterns

采用野外调查和室内分析相结合的方法,对退耕还茶地和退耕还林地土壤水稳性团聚体及其有机碳分布特征进行研究。结果表明:(1)不同土层退耕还茶地土壤各粒径水稳性团聚体占总团聚体的比例均以<0.25mm的含量最大,且与其他粒径间存在极显著差异;除2～1mm粒径外,退耕还茶地土壤与退耕还林地同粒级水稳性团聚体含量差异不显著。(2)0-20cm土层,团聚体的平均重量直径和平均几何直径表现为退耕还林较退耕还茶大,虽退耕还茶地破坏率与退耕还林的差异不显著,但退耕还茶地土壤团聚体破坏率高于退耕还林地的;20-40cm土层结果与之相反。(3)0-20cm土层,退耕还茶地随着水稳性团聚体粒径的减小土壤有机碳含量呈先减少,再增加,然后减少,最后增加的变化,且退耕还茶地土壤有机碳含量较退耕还林的高;20-40cm土层,退耕还茶地随着水稳性团聚体粒径的减小土壤有机碳含量呈先减少,再增加,最后减少的变化,除0.5～0.25mm和>5mm这2个粒级外,退耕还茶地土壤有机碳含量较退耕还林的低。

The distribution characteristics of soil water-stable aggregates in the conversion of farmland to tea plantations and the organic carbon contents in soil water-stable aggregates were studied by the combinative means of field investigation and laboratory analysis.The results showed that：（1）Soil water stable aggregates of the total proportion of aggregates were dominated by 0.25 mm particle size,and the particle size and the other were significant differences.Except for 2~1 mm particle size,the same size particle of them was not significant differences between the conversion of farmland to tea plantations and the conversion of farmland to woodland.（2）In 0-20 cm soil layer,mean weight diameter and geometric mean diameter of aggregate to the conversion of farmland to woodland were higher the conversion of farmland to tea plantations.The destruction rate of them were not significantly different between the conversion of farmland to tea plantations and the conversion of farmland to woodland,however,the destruction rate of soil aggregates to the conversion of farmland to tea plantations was higher than that of the control.The results were the opposite in 20-40 cm soil layer.（3）In the conversion of farmland to tea plantations,soil organic carbon content of water stable aggregates was reduced first,then increased,decreased,in the last increased with the decreasing aggregate particles and soil organic carbon content of all particle sizes were higher than those of the control in 0-20 cm soil layer.In the conversion of farmland to tea plantations,soil organic carbon content of water stable aggregates was first reduced and then increased and decreased at last with the decreasing aggregate particles,and soil organic carbon content were higher than those of the control in 20-40 cm soil layer except for the two fractions of 0.5~0.25 mm and 5 mm.