Atributos de solos e sua relação com o processo de desertificação no semi-árido de Pernambuco

Abstract

To analyze the process of degradation that comes from natural causes and / or anthropogenic influences is necessary the use of tools, preferably the easy ones to purchase, indicating the stages of degradation in order to make a correct management and indication of a possible use or recovery of these areas. Among the parameters subject to evaluation, attributes related to soil (especially organic matter) and vegetation (litter) have received credit. Thus, the aim of this study was to analyze the variability of microbiological and chemical attributes of soil and fractions of litter and organic matter to use such variables as indicators of processes of desertification in areas under increasing levels of degradation in the semiarid region of State of Pernambuco. Areas were sampled at different stages: conserved, moderately degraded and heavily degraded in the Floresta city, Pernambuco state, Brazil. In each area four sites were selected for sampling and made seven collections, totaling 28 points per sampled area. Soil samples were collected at depths of 0-10, 10-20 and 20-30 cm in dry and rainy periods. The litter, collected in 1 m2, was separated into woody and non-woody, and quantified the dry mass of each fraction. Were made physical (size and bulk density), chemical (pH, chemical fractionation of soil organic matter, exchangeable bases, potential acidity, soil organic carbon, carbon stocks, available phosphorus and cation exchange capacity) and microbiological (microbial biomass carbon, basal respiration, microbial and metabolic quotients) of soil. The data were analyzed taking up methods of descriptive statistics, analysis of main components and t test. About the litter, the woody fraction, stored on the healthy environment, was higher than non-woody and there was a 57% reduction of stored in the environment between the rainy and dry period. The stock of carbon in the soil decreased with depth increasing and degradation level. For chemical attributes could be observed that on the 0-10 cm depth layer, they can be used as indicators of areas with different degradation levels. The microbial biomass carbon and soil basal respiration were higher in the preserved areas during the dry period. The microbiological attributes, with emphasis on the carbon of the soil microbial quotient can be used as indicators of soil quality.