Dynamics of carbon stocks and soil physical indicators quality under different subsoiling times in the Brazilian Cerrado biome

This study evaluated the relationship between subsoiling time elapsed since subsoiling and regenerative management on organic carbon (OC) stocks and soil physical quality in the Cerrado biome. In Sapezal, MT, Brazil, an on-farm study was conducted on Oxisols. Treatments consisted of 1, 6, and 10 years since subsoiling, with soybean cultivated in summer and cotton in autumn, in very clayey soil. The following soil properties were analyzed: bulk density (BD), total porosity (TP), macroporosity (Macro), bulk air capacity (ACb), and OC stocks. The results showed that regenerative management in clayey soils maintains OC stocks equivalent to those found in the native area (NA), regardless of the depth analyzed (15 to 30 Mgha^-1). Physically, the managed soils showed similar BD to that of the forest throughout the profile down to a depth of 80 cm. However, at the surface (5-20 cm), subsoiling (1, 6, and 10 years) showed lower Macro (17%) and ACb (20%) (an average 40% reduction in aeration) compared to the NA. However, the residual effect of subsoiling is significant in the implement's action layer (30-40 cm), where Macro (~20%) and AC (~25%) equal the NA values. Clayey soils under regenerative practices and occasional subsoiling maintain physical quality and carbon stock for up to a decade. Sub-surface macroporosity and air capacity are the main indicators of the need for new mechanical intervention, given the high operational risks and costs associated with this practice.