The increasing need for food, space and other conditions for human survival generate greater anthropic interferences with the environment. Intensively and improperly tilled soils are degraded and illegal civil construction in rural areas is causing problems. Different techniques are being used to ameliorate these soils, mainly by the addition of organic matter, but information on the time required for soil recovery, influence of the organic matter type and on indicators of soil alterations is still rare. Our study aimed to recover the properties of an Oxisol used for the leveling and implantation of the hydroelectric power station of Ilha Solteira, São Paulo. Bulk density and water infiltration rate were used as indicators of soil physical quality. The experiment was carried out in an area where a layer of 8.60 m of soil had been removed. The experiment had a randomized block design with five replicates and five treatments: control plot (open soil without amelioration); tree species Gonçalo-alves (Astronium fraxinifolium Schott); Gonçalo-alves + Canavalia ensiformis; Gonçalo-alves + Raphanus sativus; and Gonçalo-alves + Brachiaria decumbens + sewage sludge (60 Mg ha-1). Bulk density was evaluated before and 356 days after treatment installation, whereas soil water infiltration was determined 188 days after treatment installation. Improvements in the soil quality where obtained with tillage and sewage sludge and green manure application. Bulk density and soil water infiltration were useful as indicators of the improvements. Different sources of organic matter added to the soil and the action of soil tillage interact in a similar way in the recovery of soil quality, but the Gonçalo-alves trees grew highest with the combination of sewage sludge and Brachiaria decumbens.
soil degraded; soil physical properties; green manure; sewage sludge
