Compartimentos de C, P e N em solos sob pastagens degradadas na região sul do Estado do Espírito Santo

Abstract

The objective was to study the soil C, P and N compartments in soils under pasture with two levels of degradation in two seasons (winter and summer). It was assumed that the levels of the total compartments of these elements in soils under pastures used for years are reduced, mainly impacting labile compartments in relation to soils under native vegetation. The study was carried out in the Caparaó Capixaba region, located in the south of the state of Espírito Santo, belonging to the municipality of Alegre. Soils were collected in nine different areas, three in forest fragments (FF), three in pastures with a low level of degradation (PBD), and three in pastures with a high level of degradation (PAD). In each of the study areas, collections were performed at two depths (0 - 0.1 m and 0.1 - 0.2 m), with three replications. Analyzes of total organic C, labile C, recalcitrant C, light organic matter, C of microbial biomass, total N, anaerobically mineralizable N, microbial biomass N, sequential fractionation of P (FSP) and enzymatic analyzes (acid phosphatase, beta -glucosidase and dehydrogenase). The C, P and N compartments of the soil under PAD were reduced in relation to the soil under FF. For COT, the environments under pasture corresponded to approximately 47.2% of the levels obtained in FF and, CL and NT corresponded to more than 60%. The low rate of enzymatic activity in the labile fraction of the FSP caused the organic P of the soil to be higher in PAD than in PBD. The moderately labile fraction of the FSP showed the highest levels of P in all environments.