Estoque de carbono do solo em distintos sistemas de produção de pecuária

Abstract

: Management systems with permanent vegetation and less soil disturbance, such as permanent preservation areas and cover cropping systems, promote greater carbon accumulation in the surface soil layer, while systems with greater disturbance, such as intensive grazing, reduce carbon stocks in this layer but may favor accumulation in deeper layers due to the presence of forage roots and soil compaction. The aim of this study was to evaluate the effect of different land use management systems, including crop rotation, cover cropping, intensive grazing, and native vegetation, on carbon stocks at different soil depths. This experiment was conducted at Campo Alegre Farm, in the municipality of Chapadão do Sul, Mato Grosso do Sul. Four different land use management systems were evaluated: (i) a cropping system between Urochloa decumbens and soybean, in which the forage is used exclusively as cover crop, being subsequently desiccated for direct soybean cultivation (T1); (ii) integrated crop-livestock system (T2); (iii) a permanent preservation area with typical cerrado vegetation characteristics as a parameter of an equilibrium environment (T3); and (iv) an area subjected to intensive cattle grazing for at least 10 years (T4). The assessments took place in August 2024, during the dry season in the region. Five soil samples were collected from each area at three different depths. Soil carbon was determined by measuring total organic carbon (TOC) concentrations by collecting soil samples at georeferenced points at depths of 0–10, 10–20, and 20–40 cm using a probe. The results demonstrate that soil carbon stocks are strongly influenced by the type of management adopted and the depth analyzed. Native cerrado vegetation (T3) presented the highest carbon stocks in the surface layer (0–10 cm), serving as a reference for soil in ecological equilibrium. Notably, the rotation system between Urochloa decumbens and soybean (T1), using forage exclusively as cover crop, achieved carbon levels similar to those of native vegetation, demonstrating the potential of these systems for soil carbon conservation and sequestration. In contrast, management with intensive cattle grazing (T4) resulted in the lowest surface carbon stocks but showed greater accumulation in the 20–40 cm layer.