Abstract

The Quirinopolis microregion (QMR) is located in the Southwestern Goiás State, and represents the recent expansions of sugar cane crops in the state. The maintenance of the agricultural and forest ecosystem productivity depends largely on the organic matter transformation process and therefore on the microbial biomass. The goal of this study was to evaluate the effects of the different management methods used in sugar cane cultivation on soil microbiological parameters and on indices derived from dystroferric (DfRO) and dystrophic (DRO) red oxisols in the region of Quirinopolis, Goiás. Eight sampling sites were selected in this study within areas occupied by DfRO and DRO, and two reference sites with semidecidual forest vegetation. The microbial biomass of the soil planted with sugar cane responded to changes caused by the two different soil management types (fertilized and not fertilized), so it may be considered a potential soil quality bioindicator. The soil profiles subject to crop succession before planting sugar cane favored the maintenance of the soil microorganism community in regards to other managements. DfRO profiles previously planted with soybean showed the best physical and chemical condition for a dynamic biomass balance. Profiles with vinasse showed no improvement in the development of soil microorganisms nor better physical and chemical conditions.

Key words: Soil quality, bioindicators, organic C, fertilization, soybean crop, vinasse.