Descomposition of crop residues under no-till management

Wheat, corn, soybeans and wheat after corn or soybeans

Abstract

The rate of decomposition of corn, wheat and soybean residues located on the soil surface and its modification through the crop sequence (soybean-wheat and corn-wheat) was studied. Dry weight and N concentration during 248 days was determined. The rate of decomposition of the soybean stubble was significantly higher than corn and wheat stubble (p<0,05). As a result of an increase in the amount of N immobilized the N concentration increased with time in corn and wheat. In soybean the N concentration and the dry weight were proportionally reduced and the amount of immobilized N in the stubble descended throughout the period. The wheat straw decomposition on soybean stubble was faster than on corn stubble. Difference in the amount of immobilized N did not exist on soybean or maize stubble but the time of N immobilization was significantly lower on soybean residue (p<0,05).