Caracterização da matéria orgânica do solo de áreas com diferentes coberturas vegetais no semiárido de Pernambuco

Abstract

The evaluation of soil quality is an important tool to monitor their degradation and to sustainable practices implementation, by indicators that can relate to soil quality with agricultural activity. The Caatinga, an exclusively Brazilian biome, has a high degradation rate, resulting of human action in inadequate soil management. The objective was to evaluate changes of chemical and biological indicators of organic matter due to the seasonality in preserved and disturbed areas of Caatinga ecoregions in Pernambuco, as well as qualitative characteristics of soil organic matter in these environments and uses. Three areas were selected: one in Buíque and two in Serra Talhada, in each area were studied two conditions of land use (soil in areas with preserved Caatinga coverage and areas with agricultural use).Soil samples were collected between September/2014 and September/2015, covering dry and rainy seasons in semiarid region. In each use and area, there were collected three composite soil samples at layers 0-5, 5-10 and 10-20 cm. Analysis to chemical and physical soil characterization were carried out in addition to biological analysis of total organic carbon (TOC), labile fractions of oxidizable carbon (LFCO), microbial biomass carbon (MBC), basal soil respiration (BSR), microbial quotient (qMIC), physical fractionation of organic matter (POM), physical fractionation of organic matter associated with mineral (MOM) and chemical fractionation of humic substances (HS).Data were analyzed by T test, at 5% probability. It was observed that all relevant variables are influenced by seasonality, and soil texture to LFCO, MBC and TOC, indicating a greater influence on labile carbon fractions.While the characterization by FTIR set directly related to carbon in MOP fractions with AH and AF, and MOM with humin.