Litter decomposition and nutrient release in different land use systems in the Brazilian semi-arid region

Abstract

Climate and litter quality change the dynamics of soil organic matter (SOM) in agricultural systems, directly influencing the soil biological activity and, consequently, energy and nutrient cycling. This work evaluated the dynamics of organic carbon decomposition and nutrient release in litter in three land use management systems. The study was carried out under semi-arid conditions in Minas Gerais State, Brazil, using decomposition bags arranged in a randomized block design and four replications. The treatments consisted of three land use systems (native forest, corn, and cocoa) and seven evaluation times: 0, 30, 90, 150, 210, 270, and 330 days. Was evaluated dry matter production, litter decomposition in polyamide bags, and nutrient release (N, P, K, S, Ca, and Mg). Systems with native forest, cocoa and maize had similar average monthly litter production, a fact linked to the climate conditions. While in the semi-arid climate, the full-sun cocoa system showed a sudden oscillation in relation to the organic carbon content up to 330 days, the native forest and corn systems were more balanced, whitout significant changes. The higher litter C/N ratio in relation to the native and corn systems favors the maintenance of organic C levels in the soil. K release has a similar behavior in cultivated soils and occurs more quickly when compared to the native system. Regarding the other macronutrients, the soil in the cocoa production system showed the highest mineralization. Periods of accumulated precipitation accelerate litter decomposition and macronutrient release. The results of this study give more insight into the carbon dynamics and nutrient release from litter as a function of land use systems in a semi-arid region.