CHEMICAL AND MICROBIOLOGICAL PROPERTIES OF AN EUTROPHIC OXISOL UNDER RIPARIAN FOREST BUFFER REFORESTATION AND PASTURE

Regardless of their ecological importance, riparian forest strips are frequently suppressed to allow greater expansion of arable and urban areas. Agroforestry might be an effective alternative to recompose riparian forests. Soil chemical and microbial properties are important environmental indicators to evaluate the reclamation process. This study tested the hypothesis that, in the course of time, reforestation by means of agroforestry improved soil microbial and chemical properties in a riparian forest buffer. Soil samples were collected from three layers (0.0-2.5; 2.5-7.5; 7.5-20 cm) in two sectors of a reforested riparian buffer strip in Cananéia Farm, São Paulo state, Brazil, one 18 years old and other 28 years old, and in an adjacent pasture area. The samples were assessed for pHH2O, available P and K, exchangeable, Ca, Mg and Al, H+Al, sum of bases (SB), pH 7.0 CEC, percent base saturation (V), soil organic matter (SOM) and light organic matter (LOM). Microbial biomass carbon (MBC) and nitrogen (MBN) were analyzed only in the first layer. The pattern for Ca, Mg, SB and V (all layers) was 28-year-old sector = 18-year-old-sector > pasture. The SOM at 0.0-2.5 cm was higher in the 28-year-old sector. The LOM pattern was 28-year-old sector > 18-year-old sector > pasture. MBC did not differ among areas. MBN was significantly higher comparing the 28-year-old sector and the pasture area. The results probably reflected the higher litterfall and the N-richer organic matter in the reforested sectors. Reforestation by means of agroforestry improved soil quality, contributing to the ecosystem sustainability.