Spatial distribution of acidity components and oxidizable carbon fractions in a silvopastoral system

Abstract

The silvopastoral system (SPS) stands out as an agroecological production system that has improved the soil's chemical quality. However, these chemical properties may have distinct changes with greater or lesser distances from the tree row tracks of the silvopastoral system. The objective of this study was to investigate the effects of the distance of the soil sampling points from the eucalyptus tree rows in a 2-year silvopastoral system on acidity components and oxidizable organic carbon fractions of the soil, as well as to compare these chemical properties with the conventional pasture system and native Cerrado vegetation. In the silvopastoral system (SPS), the soil samples were collected at 2.5, 5.0, 7.5, and 10 m of transverse distance from the eucalyptus tree row tracks. Soil samples collected in a conventional pasture area (CP) and a native Cerrado vegetation area (NV) were used as reference treatments. Soil samples were collected at depths from 0.0–0.10, 0.10–0.20, and 0.20–0.30 m. The acidity components (pH, Al3+ and H + Al) and oxidizable organic C fractions (F1: labile fraction; F2: moderately labile fraction; and F3: poorly labile fraction) were determined. The results showed that the lowest soil acidity level was observed at 2.5 and 10.0 m distances from the eucalyptus tree rows. However, the spatial distribution of soil sampling points to the eucalyptus tree rows in a 2-year silvopastoral system did not change the oxidizable fractions of the soil organic carbon. The 2-year silvopastoral system and native Cerrado vegetation area had the highest concentrations of organic carbon in the labile (F1) and poorly labile (F3) fractions in the soil profile compared to the conventional pasture system. A 2-year silvopastoral system in a low fertility tropical soil from the Brazilian Cerrado has not yet been able to improve the soil's chemical quality; therefore, further research should be carried out to investigate the medium and long-term effects of the silvopastoral system on the acidity components and oxidizable organic carbon fractions of the soil.