Decomposição de resíduos de leguminosas cultivadas em sistema de aléias

Abstract

Alley cropping is characterized by planting leguminous trees between rows of crop species of economic interest aiming at facilitate, the decomposition of biomass of leguminous trees as well as, the return of nutrients to the soil for use by crops. This work has, for purpose, assess the decomposition and release of nutrients from the biomass of leguminous shoots used in this system of cultivation. Thus, the experiment was conducted at Maranhão State University (UEMA), consisting of four leguminous plants (Acacia mangium, Cajanus cajan, Clitoria fairchildiana and Leucaena leucocephala) in different combinations. We used litter bags to evaluate the data. Within each bag were placed 40 grams of leaves and branches of two combined leguminous, which were distributed on the soil surface to decay. We considered four periods, i.e., of 30, 60, 90 and 120 days for withdrawl from the material distributed in the bags for decomposition in order to compare with the material removed for examination, immediately after the pruning of the branches of leguminous trees, considered as "zero mark". The experimental data showed that Leucaena leucocephala combined with Cajanus cajan and Clitoria fairchildiana presented the highest factor of decomposition of biomass at 30 days and Acacia mangium combined with Cajanus cajan and Leucaena leucocephala had the lowest rate of decomposition during the same period. The release of nutrients in the period of 120 days was observed in all combinations with N, P and Mg, except with Ca because the combinations Clitoria fairchildiana with Leucaena leucocephala and Acacia mangium with Leucaena leucocephala showed no release of this nutrient.