INDICATOR ATTRIBUTES OF SOIL QUALITY IN AREAS UNDER DIFFERENT LAND USE SYSTEMS, IN THE WESTERN AMAZON

Resumo

The anthropization of natural environments, when performed inadequately, promotes the disruption of the ecological balance and can influence the fauna, flora and biodiversity in general, including the edaphic environment and its components. The objective was to evaluate the soil attributes in areas with different types of vegetation cover and different forms of soil management. The study was carried out in native forest area (Subperennial Equatorial Forest) and cultivated area (annual species), in Porto Velho, Rondônia, Brazil. Samples were collected in two layers (0-10 and 10-20cm), on a Latossolo Vermelho-Amarelo, to evaluate microbial biomass by the fumigation-extraction (FE) method, as well as the chemical and physical soil attributes. It was possible to verify a significant increase in soil density and reduction of moisture and improvement of chemical attributes resulting from the use of the area. The organic matter content decreased sharply in the managed area (25%), compared to the forest, in the superficial layer (0-10cm). Microbial C-biomass under the native forest showed 54% higher mean value (883 mgC g^-1) compared to the managed area (410 mgC g-1) in the superficial layer. The microbial N-biomass ranged from 21.3 to 19.5 mgN.g^-1 in the native forest area, and from 9.3 to 11.5 mgN g^-1 in the managed area, respectively in the 0-10 and 10-20cm layers. In the native forest area, the addition of organic matter to the soil by the vegetation litter was an important conditioning factor for the microbial community, demonstrating the use of this attribute as an indicator of soil quality.