EFECTOS DEL CULTIVO DE SOJA TRANSGÉNICA EN SIEMBRA DIRECTA SOBRE LA TAXOCENOSIS DE ÁCAROS EDÁFICOS EN HAPLUSTOLES DEL CENTRO DE CÓRDOBA.

The lack of mechanical mixing of stubble with mineral soil under no-tillage means that this management technique depends mainly on soil organisms to function properly, resembling natural ecosystems. Mites are one of the most abundant and diverse groups of soil mesofauna. The aim of this study was to evaluate changes in mite taxocenosis produced by soybean monoculture under no-tillage with respect to the original natural grassland taxocenosis, in Typic Haplustolls of General Deheza basin, Córdoba. Changes in soil properties related to these organisms were also evaluated. The no-tillage system led to a decrease in mite abundance in litter and soil and changes in the dominance of different taxa: natural grasslands were dominated by Oribatida and managed sites were dominated by Prostigmata. In this sense the mesofauna of no-tillage sites are more similar to those of tilled land than to those of natural soils. It is suggested that the higher bulk density, the lower soil organic matter and moisture content of managed soils, the agrochemical load and the low return of soybean residues are the factors that best explain the differences in faunal communities. The changes observed in mite taxocenosis affect the litter decomposition process, resulting in a decrease in soil quality. [ABSTRACT FROM AUTHOR]