Owing to long duration of cultivation and mismanagement of black soils, the quantity and quality of organic matter and other main indices of soil fertility were decreased gradually. At the same time the properties of colloidal complex, contents of organic matter and nutrients, buffer capacity and water- and nutrient-holding capacity were decreared, and the absorbing capacity of phosphorous was increased. While with the increasing of the quantity of organic matter and regeneration and improvement in the quality of organic matter in soil by application of organic manure, some indices of soil fertility were increased correspondingly. At the same time the properties of the colloidal complex were improved, the contents of organic matter and nutrients, availability of phosphorous, buffer capacity, water and nutrient-holding capacity were increased, and combined status of humus was also improved, which brought about the promotion of the fertility of black soils.