Decomposition and nutrient release from legume and non-legume residues in a tropical soil

Understanding the dynamics of decomposition and release of nutrients from plant residues of different covers, in association or succession, is essential to define more sustainable management strategies in tropical soils. The objective of this study was to estimate the decomposition rates and the release of nutrients during the decomposition of different crop residues with different chemical compositions when in association (Mix) or in succession as residue management. A study was carried out with the respective treatments in a (2 x 6) + 1 factorial scheme: (a) without and with the addition of Pennisetum americanum residue (L); and (b) six residue crops (legumes and non-legumes) and one additional treatment with residue of millet only; with destructive samples over time (0; 0.08, 0.25 and 0.41 years after incubation). The treatments were distributed in a randomized block design with four replicates. The plant material was processed, and the contents of macro- and micronutrients were determined. The decomposition rates and release of nutrients from the residues were estimated by fitting nonlinear regression models. Residues of only non-legumes, with the exception of sunflower, tend to accumulate and degrade more slowly, resulting in a slow release of nutrients to the soil. Legume residues are more easily decomposed, enabling faster delivery of the nutrients available to the soil. Despite the faster degradation of legume residues, brown hemp was more resistant to decomposition. A combined supply of legume and non-legume residues favoured a diversified pattern of decomposition and release of nutrients among the different residues studied. The knowledge of the biochemical composition, as well as the dynamics of decomposition and release of nutrients from leguminous and non-leguminous residues, will directly influence the management to be adopted and the functionality of the residues in the soil. Highlights Decomposition of associated plant residues as soil fertility management strategies for tropical soil were explored. Interactions of decomposition dynamics of plant residues applied to tropical soils were investigated. The combined supply of legume/non-legume residues favours greater decomposition and release of nutrients. Biochemical composition of plant residues directly influences the sustainable soil fertility management strategies to be adopted.