LAUSR

The study aims to verify whether the introduction of the specie Pinus taeda L. in soil under natural field alters the aggregation of Haplumbrept, at differents rotations. The study was conducted in the region of Campos de Cima da Serra, in the municipality of Cambara do Sul – RS state, Brazil. In order to achieve the goal above described, were selected two study areas, one in the first rotation (RT1) and another in the second rotation (RT2), with 13 years of old. For each stand, a combined area of natural field adjacent (control) was assessed. In each area, five trenches were opened and soil samples collected at depths from 0.0 to 0.05, 0.05 to 0.20 and 0.20 to 0.40 m to determine the percentage stable aggregates in each class (AGRI) and geometric mean diameter water stable aggregates (DMG). There was no change in the aggregate stability in the surface layer (0.0 to 0.05 m). However, the subsurface layers (0.05 to 0.20 and 0.20 to 0.40 m), just RT1 maintained stability of larger aggregates. Due to management adopted in RT2, such as burn and clear cut, there was a reduction in stability and increase in macro-aggregates smaller aggregates, whereas in the natural field stability in depth was maintained.