黑土坡面土壤团聚体组成特征研究

通过对径流小区坡面土壤团聚体含量的分析,探讨了不同坡度条件下,黑土坡耕地土壤团聚体的组成及分布规律。在3°～18°的坡面上,土壤大团粒和中团粒含量与坡度呈显著负相关关系,并且随坡度的增加,土壤团聚体的几何平均直径(GMD)与平均重量直径(MWD)均显著减小,土壤抗蚀性下降,潜在侵蚀危险程度增大。与免耕平作相比,在3°～6°缓坡上,横坡垄作方式的土壤团聚体D50值大;而9°坡面上部,横坡垄作的D50值大,坡下部免耕平作的D50值大。表明黑土区缓坡耕地采用横坡垄作方式有利于土壤团聚体的保持;9°以上坡耕地,免耕平作方式坡下部土壤抗蚀性较强。

Composition Characteristics of Black Soil Aggregates on Sloping Farmland

Based on the analysis of soil aggregate content in runoff plots,the composition and distribution of black soil aggregates on sloping farmland with different slope degrees are discussed.Results show that both the content of large soil aggregates and the content of medium soil aggregates have significantly negative correlation with slope degree in 3°~18° plots.With slope degree increasing,geometric mean diameter(GMD)and mean weight diameter(MWD)decrease evidently,soil anti-erodibility decreases,and potential erosion risk increases.In 3°~6° plots,D_50 value for cross tillage is higher than that for no-tillage,but in the upper of 9° plot,D_50 value for cross tillage is higher and in the lower of 9° plot,D_50 value for no-tillage is higher.This indicates that cross tillage mode is beneficial to maintain the amount of black soil aggregates on gentle sloping farmland and soil in the lower of 9° plot under no-tillage has strong anti-erodibility.