Fertility of a Recovered Soil with Sewage Sludge and Native Species of the Atlantic Forest.

Sewage sludge has shown high potential to recover degraded areas, because has high levels of organic matter and nutrients, essential to improve the physical and chemical characteristics of the soil. The objective of this study was to assess the fertility of a degraded soil, the surface layer (0-20 cm) after 10 years of application of sewage sludge and planting native species of the Atlantic Forest. The experiment was conducted at Fazenda Entre-Rios, owned by Suzano Papel e Celulose, in Itatinga, São Paulo, Brazil. The experimental design was a randomized block with four replications, six doses of sewage sludge (0, 2.5, 5, 10, 15 and 20 t ha-1), conventional chemical fertilizer and only with potassium application, totaling eight treatments. After 10 years  of installation of the experiment, there was a significant effect of the application of sewage sludge on organic matter, pH, phosphorus, sulfur, copper, iron, zinc, acidity potential and capacity of the soil exchange. The levels of these nutrients remained high even after 10 years of application of sewage sludge, and the highest values were observed in the soil with doses of 15 and 20 t ha-1 sludge. Calcium, magnesium, potassium, boron, manganese, sum of bases and base saturation were not affected by the application of the residue. The sewage sludge application is useful to recover degraded soils, because it improves their chemical characteristics and is a good alternative to the final destination of this residue.