A exclusão do pastoreio e sua influência na atividade enzimática de solos da Caatinga em processo de desertificação

Abstract

The unsustainable exploitation of natural resources, culminated in the indiscriminate use of the Caatinga biome. Extensive livestock activities and rudimentary agriculture, which have been occurring for decades, together with the unique characteristics of climate, soil and vegetation, favor the degradation of large areas. This fact favored the emergence of areas susceptible to desertification, which was intensified by several natural and man-made processes. Considering the soil as a reservoir of great biological diversity, it is a priority to carry out studies that seek to measure its health and / or quality. In this sense, the enzyme activity of the soil in areas undergoing desertification is poorly understood. Furthermore, little is known about how grazing exclusion can recover microbial metabolism of soils in an advanced degradation process in the Caatinga. The study aimed to analyze an activity of the enzymes β-glycosidase, arylsulfatase, acid and alkaline phosphatase of soils inserted in the desertification nucleus of Irauçuba (CE), using soils from 3 different subareas as treatments: 1. Caatinga natural vegetation ( VN), 2. natural recovery of Caatinga (RN - exclusion of grazing for 19 years) and 3. areas in an advanced process of degradation by overgrazing (AD). These soil people were collected in 3 different areas, being evaluated by 27 (3 treatments x 3 areas x 3 repetitions). The enzymatic determinations followed the methods based on the colorimetric measurement after the release of ρ-nitrophenol, previously incubated in buffers and specific specifications. The AD treatment presents, in general, lower values for the analyzed enzymes. Β-glycosidase activity was superior in the RN and VN treatments, when compared to AD. For acid phosphatase, the RN treatment for complication superior to AD. In this case, the VN treatment showed intermediate results. For arylsulfatase and alkaline phosphatase, in general, there is no significant effect, with small variations between areas. As a conclusion, it is updated that the areas in RN managed to recover the enzymatic potential of the soil, in some cases surpassing the activity of the VN subareas. This study highlights the importance of soil management for essential sustainable ecological functions in the Caatinga ecosystem, such as the cycling of C, P and S, given the participation of these enzymes in the mineralization of organic material associated with these cycles and the availability of nutrients for plants.