George Washington Carver: A National Agricultural Library Digital Exhibit

1938

National Agricultural Library

Maintenance of soil productivity is to a large extent bound up with the maintenance of organic matter, which serves to decrease the danger from erosion. Legumes take a prominent place in maintaining soil productivity. Winter legumes are most commonly depended on in the South; red clover and sweetclover in the North. Turning these crops under, wholly or in part, maintains the organic matter at a satisfactory level and adds nitrogen to the soil.

Summer legumes may and do also serve the same purpose. Cowpeas and soybeans harvested for hay do not add materially to the organic matter in soils. At best they serve as a mechanical summer cover. If turned under entirely they serve the same as crotalaria to add to the soil organic matter. Practical experience has shown that the annual lespedezas even when cut for hay will increase the following crop of cotton or corn. Data on the quantities of organic matter left in the soil by such a crop are wanting, but even when annual lespedezas are cut for hay a considerable quantity of organic material is left, and the resulting increase in crop yields is commonly impressive.

Legumes in Soil Conservation Practices