Fractions of soil organic carbon under different land uses in family farming areas

Abstract

The objective of this study was to evaluate the effect of land use on the quantity and quality of soil organic carbon (SOC) in family farming areas through the SOC fractionation. Three different land uses were evaluated (FS: secondary forest, LA: farming corn, CA: strate herbacee), in the layers 0 – 10 and 10 – 20 cm. SOC were quantified, particulate organic carbon (POC), organic carbon associated with minerals (OCAM) and oxidizable organic carbon fractions (F1, F2, F3, F4 and F1 / F4). The largest SOC concentration and its fractions occurred in the FS. The LA and CA uses reduced approximately 57 and 67% the COS content in the 0-10 cm layer and 49 and 66% in the 10-20 cm layer compared to the FS. F1 presented the highest content (22.41 g kg^-1) in FS, layer 0-10 cm, in relation to the other fractions. In the LA and CA, F4 presented the highest levels, respectively (10.64 and 10.92 g kg^-1 in the 0-10 cm layer, 9.89 and 6.19 g kg^-1 in the 10-20 cm layer). COp and COam presented higher FS content in both layers (COp = 28.75 and 15.27 g kg^-1, COam = 48.76 and 40.27 g kg^-1). The values of the ratio F1/F4 indicates that the FS area, predominate more labile fractions of SOC, since in LA and CA uses prevail more recalcitrant. Hillside areas and with fragile soils previously cultivated in intensive systems of soil revolving and with reduced organic waste, require sustainable agricultural practices to ensure the preservation and improvement in the quality of family production areas.