Compartimentos lábeis da matéria orgânica e estoques de C e N em pomar de mangueiras “Tommy Atkins” adubadas com fontes orgânicas.

Abstract

In semi-arid Paraiba the use of organic materials in fruit growing is done without technical criteria and little is known about the effects of these materials in labile compartments, the C and N stocks of soil and on its potential as a source of nutrients for crops. This study evaluated the effect of sources of organic materials on the labile compartments (microbial biomass and light organic matter) and the stocks of C and N in soil organic matter, in an orchard of mango 'Tommy Atkins' irrigated in semiarid region of Paraíba. The experiment was conducted in a completely randomized design in 9 × 2 factorial arrangement with three replications. The treatments consisted of combinations of six organic materials [poultry manure (PM), cattle manure (CM), sheep manure (SM), swine manure (SwM), chicken litter (CL) and organic compound (CO)], fertilization synthetic (NPK), control (without fertilization - TEST) and vegetation of a native forest fragment (NF) and two sampling times (dry and wet). In samples collected in the 0-5, 5-10 and 10-20 cm were determined the levels of C and N, light organic matter (LOMC and LOMN) and microbial biomass C (MBC and MBN) and estimated values relations C / N and C / N of the light organic matter, as well as relations MBC / TOC and MBC / LOMC, besides the total stocks of C and N. The results showed the influence of sources of organic material and seasonality on the labile compartments, levels and stocks of C and N in the soil, with higher values for less recalcitrant and materials in the dry season, respectively. The application of OC promoted together with the NF, higher levels of LOM and LOMC. Higher amounts of MBC and MBC relations / LOMC and MBC / TOC were obtained with the use of SwM. The application of CM and OC resulted in higher levels and stocks of C and N, respectively.