Recovery of a degraded soil with green manure and sewage sludge

The inadequate use of soils induces alterations, exhausting the productivity, and resulting in growing areas of degraded soil. This study had the objectives of a) studying alternatives to promote the formation of the A horizon of a degraded soil through the use of green manure, sewage sludge, and cultivation of a native tree species; and b) selecting soil quality indicators to detect the alterations in the surface layer. Evaluations were executed annually. The experimental design was in random blocks with six treatments and five replications. The treatments consisted of a control (without soil management); original vegetation (savannah); Astronium fraxinifolium; Astronium fraxinifolium + Canavalia ensiformis; Astronium fraxinifolium + Raphanus sativus and Astronium fraxinifolium + Brachiaria decumbens + sewage sludge (60 t ha(-1)). The following soil properties were evaluated: porosity, bulk density, exchangeable cations, pH, potential acidity, base saturation, CEC and macrofauna. The dry matter of the green manures was evaluated. and stem height and diameter of the tree species were measured. Soil mobilization or soil mobilization plus green manure or sewage sludge restored soil properties, although the effects are similar after one year. The best soil physical quality indicator was bulk density. The effects of treatments on the recovery of soil macrofauna were similar. The presence of larvae and beetles was an indication of the improvement in the soil macro/auna.