SOIL CARBON STOCKS IN COMMERCIAL CROPLANDS OF THE BRAZILIAN CERRADO

Soil carbon (C) stocks reflect the combined effects of management practices, soil properties, and climate on agroecosystem functioning. This study quantified soil carbon stocks in commercial croplands under different crop successions across four farms located in the Brazilian Cerrado, in the states of Mato Grosso (MT), Mato Grosso do Sul (MS), Bahia (BA), and Maranhão (MA).Soil samples were collected in triplicate down to 1.0 m depth in cropland areas and in adjacent native vegetation. Bulk density, total carbon, and soil texture were determined at the depth intervals of 0.00–0.05, 0.05–0.15, 0.15–0.30, 0.30–0.60, and 0.60–1.00 m. Soil carbon stocks were calculated by layer and integrated across the soil profile. Results showed that more than half of the total soil carbon stock was stored below 30 cm, highlighting the importance of subsoil carbon in Cerrado agroecosystems. Surface layers exhibited higher carbon concentrations due to inputs from aboveground biomass, while deeper layers contributed substantially to total carbon stocks due to greater soil mass and stabilization mechanisms. Native vegetation areas in MA and BA presented higher soil carbon stocks compared to croplands, whereas in MT and MS lower carbon stocks under native vegetation were primarily associated with soil texture and land-use history, as native areas are often located on marginal soils. The spatial distribution of the study sites allowed assessment of soil and regional climatic variability, particularly precipitation and temperature patterns, which are expected to strongly influence soil carbon dynamics under future climate change scenarios.