Effect of soil management on carbon stock and soil aggregation in a natural recovery area and surrounding systems, Brazil

Abstract

This study aimed to quantify total organic carbon (TOC), carbon of humic substances (HS), and their stocks and evaluate the soil structural stability of areas with different uses under sandy loam soil textureSoil samples were collected from three areas and a reference area: Permanent Pasture (PP), No-Till (NT), Private Natural Heritage Reserve in the process of natural regeneration (RPPN) and Native Forest (FN). Dry mass analysis, carbon stock quantification, chemical fractionation of soil organic matter and soil aggregation were carried out. The NF area had the highest deposition of ML. The PP and NT areas had the highest Bd. TOC and Stock-C contents were higher in PNHR, followed by NF, and STRATI was also higher in the regeneration area, and ΔStock-C was positive only in this area. The NT, PNHR, and NF areas had a higher proportion of C-FA than C-HA, but the fraction with the highest representation in all areas was C-HUM. The PP, PNHR, and NF areas obtained the best aggregate stability indicators, such as WMD, GMD, SI, and OLev, as well as a higher proportion of macroaggregates, with the NT area having low aggregate stability. In general, recovery of C contents was observed in recent years in the area of PNHR, leading to a greater storage of C, which shows a quantitative recovery of C in the soil in this area after four years of natural regeneration. Furthermore, the PP and NT areas present a lower capacity for C sequestration, mainly due to the management conditions imposed on the areas.