土地利用方式对红壤团聚体稳定性的影响

以湖南、湖北和江西3省第四纪红土母质发育的土壤为材料,应用干、湿筛法比较不同利用方式下土壤的团聚体粒级分布、平均重量直径(MWD)以及团聚体破坏率(PAD)的差异,分析在不同利用方式下土壤团聚体的分布特征以及稳定性与土壤有机碳的联系。结果表明:不同利用方式下干筛团聚体均以>5mm粒级为主,其次为<0.25mm粒级,而湿筛团聚体则以<0.25mm粒级为主。各不同利用方式土壤团聚体干、湿筛MWD值变化趋势大体一致,并且与有机质含量均呈显著正相关关系。各不同利用方式下PAD有显著差异,表现为旱地>果园>水田>茶园>林地,并且PAD与土壤有机质含量和湿筛获得的MWD值呈极显著负相关。不同有机质含量可显著影响不同利用方式下水稳性团聚体粒级分布。>5mm,1～0.5mm,0.5～0.25mm,>0.25mm粒级水稳性团聚体的含量比例均与有机质含量之间有极显著的相关关系,而5～2mm和2～1mm粒级水稳性团聚体则与有机质含量相关性并不显著。不同土地利用方式对土壤有机质含量有极大的影响,有机质含量高低表现为水田>林地>茶园>旱地>果园。

Impact of Land Use Patterns on Stability of Soil Aggregates in Red Soil Region of South China

Using quaternary red soil from different land uses collected in Hunan,Hubei and Jiangxi provinces,the distribution and stability of soil aggregates,mean weight diameter(MWD) and percentage of aggregate destruction(PAD) were studied by dry and wet sieving.Moreover,the connection of distribution of soil aggregates with stability and soil organic carbon were also discussed.The results indicated that: At different land use patterns,soil aggregates MWD was almost >5 mm and followed by <0.25 mm with dry sieving,while it was dominated by <0.25 mm by wet sieving.Soil aggregates MWD of different land use patterns was positively correlative with organic matter content no matter by dry sieving or wet sieving.The PAD diverged greatly at different land use patterns: Dry land>orchard >paddy >tea garden >forestland,and negatively correlated with organic matter content and MWD by wet sieving.The soil organic matter content was extremely correlative with water-stable aggregates with >5 mm,1~0.5 mm and 0.5~0.25 mm sizes at different land uses,while it didn’t correlated with water-stable aggregates with 5~2 mm,2~1 mm sizes.Different land use patterns affected organic matter content greatly,and the order of organic matter content was followed as: Paddy >forestland >tea garden >dry land >orchard.