Biological Activity as an Indicator of Soil Quality under Different Cultivation Systems in Northeastern Brazil

The objective of this work was to evaluate biological indicators in areas of different land uses in the northeastern region of Brazil. Agricultural areas, located in the municipality of Simão Dias, were selected for the collection of deformed soil samples in the 0-10 cm layer. The areas studied were VNT - native vegetation of caatinga; CTA - pasture of Tanzania grass intercropped with algarobeira; MCF - corn intercropped with beans in conventional cultivation; MPC - corn in monoculture under conventional cultivation and MCM - corn in monoculture under minimum cultivation. The analyzes were total enzyme activity, urease activity, acid phosphatase, β-glucosidase, microbial biomass nitrogen, microbial biomass carbon, soil basal respiration and metabolic quotient. The results were submitted to ANOVA and Tukey's test at a significance level of 5%. The results showed that the most conservationist systems of soil use provided better results through the microbiological indicators: total enzyme, ureic activity and soil microbial biomass. The indicators of acid phosphatase and β-glucosidase activity showed a significant reductions in the soil under anthropic management. They markedly in monoculture of the corn crop and conventional cultivation. The levels obtained are directly related to the different uses of the soil. We propose to make them suitable for soil quality assessment and, therefore, potential indicators for the analysis of environmental sustainability in semi-arid northeastern region Brazil. The results obtained reinforce the need for improvements in the management adopted so as not to compromise the quality of the agricultural soils of the semi-arid region.