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选用Ｎａ＋、Ｃａ２＋和胡敏酸（ＨＡ）研究不同价态的交换性阳离子、土壤有机质对纯矿物和土壤粘粒絮凝－分散的作用。结果表明：粘粒悬浮液中Ｎａ＋或Ｃａ２＋浓度较低时，土壤有机质均能提高纯矿物和土壤粘粒的分散程度，表现为粘粒悬浮液的临界絮凝浓度（ＣＦＣ）随ＨＡ添加量的增加而提高。当Ｎａ＋或Ｃａ２＋浓度较高时，有机质失去对粘粒的分散作用。用Ｈ２Ｏ２去除土壤有机质后，土壤粘粒分散程度明显下降，ＣＦＣ减小，有机质含量较高的黄棕壤ＣＦＣ下降程度大于有机质含量较低的红壤。与Ｃａ２＋作用下相比，Ｎａ＋作用下ＨＡ对粘土矿物的分散度较大，１∶１型高岭矿或以１∶１型矿物为主的红壤的粘粒悬浮液的ＣＦＣ受ＨＡ的影响大于２∶１型蒙脱矿或以２∶１型矿物为主的黄棕壤，前者的ＣＦＣ随ＨＡ含量改变的幅度较大
Na +, Ca2 + and humic acid (HA) were used to study the exchangeable cations with different valences. The effect of soil organic matter on flocculation-dispersion of pure minerals and soil clay particles was studied. The results showed that soil organic matter (OM) could increase the degree of dispersion of pure minerals and soil clay when the concentration of Na + or Ca2 + in the slurry was low. The critical flocculation concentration (CFC) of the clay slurry increased with the addition of HA And improve. When Na + or Ca2 + concentration is high, the organic matter loses its effect on the dispersion of the clay particles. With the removal of soil organic matter by H2O2, the degree of soil clay particle dispersion decreased significantly, while the CFC decreased. The degree of CFC reduction in yellow brown soil with higher organic matter content was greater than that with lower organic matter content. Compared with Ca2 +, the dispersity of HA to clay minerals is greater under the action of Na +. The CFCs of the clay suspension of 1: 1 type kaolinite or red soil with 1: 1 type mineral are more affected by HA than 2: 1 type montmorillonite or 2: 1 type of mineral-based yellow-brown soil, the former CFC with HA content changes in a larger range