Legume and Nonlegume Crop Residues as Sources of N in Oxisols and Ultisols

Abstract

Further attempts were made to explore the N supplied by legume and nonlegume crop residues through crop rotation experiments on a sandy Oxisol and a clayey Ultisol. In the initial crop, soybean yields were only fair, (1,680 to 1,792 kg/ha). Mungbeans, (1,125 to 2,044 kg/ha), winged beans, (1,456 to 2,800 kg/ha), and corn yields were good, (4,480 to 6,123 kg/ha). In the second crop (corn at both sites), grain yields were striking as a result of fertilizer N, regardless of the previous crop. On the Ultisol, corn tended to yield more following the legumes than following corn, but differences were not statistically significant. About 80% of the maximum corn yield was attained when corn followed the legumes and no fertilizer N was applied, especially in the Ultisol.