What is the impact of pasture reform on organic carbon compartments and CO2 emissions in the Brazilian Cerrado?

Abstract

The emission of CO2 from the soil in agricultural areas is the result of the interaction of several factors, including soil and crop management practices and local edaphoclimatic conditions. The dynamics of organic carbon (OC), in the midst of reform processes in agricultural areas, can be used as an indicator of chemical soil quality because carbon loss is directly related to its lability, quality, or decomposition capacity. This study aimed to evaluate the impact of the reform of degraded pastures in the soil organic matter compartment and its effect on mitigating CO2 emissions. The study was carried out in the municipality of Selviria, Mato Grosso do Sul, Brazil, in two areas destined for extensive beef cattle grazing, subsidized by the forage plant Urochloa brizantha cv. Marandu. Geostatistical meshes were installed in the areas, and soil samples of deformed and undeformed structures were taken to evaluate the physical and chemical attributes of the soil. The results indicated that soil management practices, followed by the cultivation of sorghum intercropped with U. brizantha, increased the total OC (TOC) stocks through the stable fraction (OC associated with the mineral fraction) and consequent reduction in CO2 emissions from the soil. This highlights the spatial variability in CO2 emissions and how soil attributes affect the flow of CO2 into the atmosphere. The use of multivariate geostatistics has made it possible to forecast CO2 emissions from the soil. This small-scale study provides a theoretical basis for the large-scale spatial monitoring of biogeochemical processes that control CO2 emissions in agricultural ecosystems, particularly in degraded pasture areas.