Estoque de nutrientes e decomposição da serapilheira em sistemas agroflorestais no município de Belterra – Pará

Abstract

The study on the cyclicity of energy sources in agroforestry systems allows monitoring of changes in management techniques and makes it possible to infer the sustainability of these plantations. The objective of this study was to evaluate the decomposition and nutrient release rates in several agroforestry systems in the municipality of Belterra, Pará. The litter collection was carried out monthly for a year, from September 2015 to August 2016, from four collectors arranged randomly in each area. For the litter stock, three collections were added, including the beginning of the dry period (August 2015), the beginning of the rainy season (January 2016) and the end of the rainy season (June 2016), by monographs by area. In the laboratory, the material was screened in the leaf fractions, woody material, reproductive structure and fragmented material, and the aerial part in an oven at 70 ºC. Macronutrients decomposition and release were evaluated by considering the dry mass weight using the Olson (1963) formulas. On average, the N, P and K macronutrient update rates appeared in SAF 3, which together have a specie Moringa oleifera Lam legume, as well as the highest decomposition rate (K) and the lowest renewal period (1 / k). The highest stocking rate of macronutrients was verified in SAF 2, as well as a lower rate of decomposition due to the greater accumulation of foliar fractionation, densified arrangement and the presence of a deciduous species (Spondias mombin L.) as a component of the system.