Impact of deforestation on the soil physical and chemical attributes, and humic fraction of organic matter in dry environments in Brazil

Deforestation of Caatinga and inadequate land use of these dry environments have impacted soil quality in Northeastern Brazil. The objectives of this study were: (a) to evaluate the effect of deforestation and different agricultural uses on the physical and chemical properties of soil, and humic fractions of soil or-ganic matter in dry environments; and (b) to detect the soil properties that were most affected by anthropic actions. We evaluated four dry areas in Cha-pada do Araripe, NE Brazil: preserved native vegetation; degraded native vege-tation; cassava conventional cultivation; and eucalyptus agro-energy cultiva-tion. Soil fertility, total organic carbon and humic fractions of soil organic mat-ter were lower in the degraded native vegetation area. The best indicators for soil quality evaluation were: macroporosity; bulk density; soil resistance pene-tration; sum of bases (mainly Ca2+); available P; and saturation by Al3+. Total or-ganic carbon and humic acid fractions of soil organic matter were important in improving soil quality. These properties were influenced by deforestation and agricultural uses, suggesting that the deforestation of native vegetation in dry environments has high capacity to degrade the soil, preventing its regenera-tion.