土地利用方式对紫色丘陵区土壤团聚体的影响

Effect of Land Use Change on Soil Aggregates in Purple Hilly Areas

[目的]了解不同土地利用方式下团聚体变化规律，旨在为合理优化紫色丘陵区土地利用方式、提高土壤有机碳储量及质量提供依据。[方法]采取野外调查与室内分析相结合方法，对丘陵地区紫色土林地、撂荒地、水田、旱地土壤剖面（O～40cm）团聚体进行研究。[结果]MwD值均大于0．500mm，且均随土层深度的增加而减小。林地、撂荒地、水田、旱地以大团聚体（〉0．250mm）为主，其中林地以〉2．000mm粒径团聚体为主，撂荒地、水田、旱地以0．250～2．000mm粒径团聚体为主。旱地、撂荒地〈0．250mm粒径团聚体明显大于水田、林地，特别是旱地表现出最大值。l结论l有机碳与MwD、〉2．000mm团聚体比例存在显著正相关，〉2．000mm团聚体组分有助于土壤有机碳的积累，而有机碳与〈O．053、0．053～0．250、0．250～2．000mm团聚体所占比例具有负相关关系。〈0．053、0．053～0．250mm粒径团聚体可能会抑制土壤有机碳的积累。

[ Objective ] The change of soil aggregates under different land use was studied to rationally optimize the land use in purple hilly ar-eas and provide the basis for the improvement of the stock and the quality of soil organic carbon. [ Method] Soil aggregates under woodland, wasteland, cropland and dry land in purple hilly areas were studied with field survey and laboratory analysis. [ Result] MWD in the four land use types were greater than 0. 500 ram, but MWD declined with soil depth. Woodland, wasteland, cropland and dry land were mainly existed as macro-aggregate（ 〉 0. 250 ram） , but woodland soil was mainly existed as 〉 2. 000 mm aggregate while other land use was mainly existed as 0. 250 - 2. 000 mm aggregate. The proportions of 〈 0. 250 mm aggregate in dry land and wasteland were higher than that in cropland and woodland, and which in dry land displayed the maximum. [ Conclusion] MWD and 〉 2. 000 mm aggregate proportion were significantly posi- tive｜y correlated with soil organic carbon, so that 〉2. 000 mm aggregate was helpful for the accumulation of organic carbon in soil. However, organic carbon was negatively correlated with the proportion of 〈 2.000 rmn aggregate, especially 〈 0.053 and 0. 053 - 0. 250 mm aggregate inhibited the accumulation of organic carbon in soil.