摘要
坝系土壤粒径均以粉粒为主，含量占土壤的６６％～７０％。各土壤间粉粒含量差异很小，所不同的是，坝地富粘层粗粉粒少细粉粒多，砂粒少粘粒多，坝、坡轻壤层反之。土壤ＯＭ、ＴＮ主要集中在粘粒中，其浓度在粗细颗粒中差别悬殊。ＴＰ及ＴＫ在粗细颗粒中这种差别就较小。土壤中各形态锌均随着土壤颗粒变细而浓度增加，在＜０．００５ｍｍ粒径中浓度陡然提高。故坝地富粘层中ＯＭ、ＴＮ、ＡＺｎ的含量最丰。上述粒径及养分分布特点，揭示了在泥沙迁移淤积过程中，坝地不同部位土壤养分差异的内在原因。
Particles in dam system soil are component mainly of silt, and its amount account for 66～70 percent in the soil. The marked difference in various soil are that there are many fine silt and clay but rather less for coarse silt and sany in strong accumulation clay layer, the loamy layer are just the contrary. The amount of OM,TN are primany concentrated on fine particles (<0005mm), the concentration difference of OM, TN between coarse and fine particles are larger in dam system soil, but TP,TK are smaller. The concentration of various zinc forms in the soil was found to increase progressively with fine of soil particles and the concentration increase suddenly in the fine particles (<0005mm). Therefore the highest content of OM,TN,AZn exist in strong accumulation clay layer. The above mentioned have showed the cause for nutrient condition difference in various location of dam system soil under the migration-illuviation process.
