The aim of this paper was to evaluate biological indicators of soil quality under conventional and organic farming systems of fruits in Piauí state. Soil samples were collected in the projection area of plant canopies and in the row at a 0-10, 10-20 and 20-40 cm depths in two areas: organic farming system with "acerola" orchards (SO), conventional farming system with guava orchards (SC). An adjacent area with native vegetation (AVN) was used as referential, being collected soil samples in all area. The variables studied were soil basal respiration, organic and microbial carbon and respiratory and microbial quotients. The higher value of basal respiration was observed in soil of SOcanopies, in 10-20 cm depth. The soils samples collected in the area of native vegetation (AVN) and under the plant canopies in organic system (SOcanopies) showed high organic carbon in the surface (0-10 cm depth) and (20-40 cm depth). Compared with soil of AVN, there was an increase in the carbon of microbial biomass (Cmic), in 0-10 cm and 10-20 cm depth, for SOcanopies and SCcanopies. Organic system increased soil microbial activity and organic carbon content, showing benefits for this farming system.
Sustainability; microorganisms; microbial activity
