Abstract:Four group of water-stable microaggregate were separated from calcareous soils by means of three colloidal-dispersing methods.They are the group dispersed by sodium (GI1),the group dispersed by decalcification (GI2),the group dispersed by grinding (GII) and the group dispersed by water.The contents of humus,fulvic acid and clay mineral in these four groups showed a tendency as follows:GII>GI2>GI1Go.The content of microaggregate<10 μ in four groups is positively correlated with the contents of particles<10 μ,CaCO3 and in soil.