LAUSR

ABSTRACT This study evaluated the mass decomposition and mineralization of nutrients from a green manure composed of mixtures of legume and grass in tropical conditions. The experiment was carried out in a greenhouse, with green manure biomass mulched on top of the soil in pots and covered with a nylon screen. The five treatments comprised different ratios of jack bean (JB) and millet (M) providing the same amount of total N: 100JB, 75JB:25M, 50JB:50M, 25JB:75M and 100M. Samples were collected at 0, 40, 80, 120 and 160 days after mulching. The contents of C, N, P, K, Ca, Mg, S, cellulose, hemicellulose, lignin and the C:N, C:S and lignin:N ratios were determined. The chemical characteristics varied according to the legume and grass mixtures. The 100JB had the highest N content and lowest contents of cellulose, hemicellulose, lignin, C:N and lignin:N. The opposite was found for the 100M. The N mineralization process correlates positively with total N concentration and negatively with lignin content, C:N and lignin:N ratio and, these were the most important factors to predict the N mineralization in mixtures of legume and grass in tropical conditions.