Carbon Stocks in Brazilian Latosols (Oxisols) from Different Morphoclimatic Regions and Management Systems

Abstract

Abstract Soil organic matter (SOM) is the greatest carbon reservoir in the terrestrial ecosystem, reaching approximately 1.500 × 109 t of carbon (C). The knowledge of the size and dynamics of this compartment is essential for carbon stock evaluation, leading to a national inventory of carbon fluxes, as well as the modeling of tropical carbon cycles. Latosols (oxisols) cover approximately 40% of the Brazilian territory, being important with regard to SOM accumulation. This process can occur both at the surface and within minute aggregates at greater depths. The mean C stock values were calculated for Brazilian Latosols (Red Latosol—RL, Yellow Latosol—YL, Red Yellow Latosol—RYL, and Humic Latosols—HL); in addition, we evaluated the effects of climate, vegetation, and land use on C stocks. A database was used of organic carbon contents of A and B horizon of Latosols from different morphoclimatic regions (humid tropical northern Brazil, semi-arid, northeast, coastal Atlantic southeast, dry topical central, and subtropical southern) compiled from the extensive RADAMBRASIL and EMBRAPA soil surveys. The mean C stock values of Brazilian Latosols are: 6 and 13 kg m−2 for YL; 7.5 and 11 kg m−2 for RL; 6.8 and 8.8 kg m−2 for RYL; and 30.16 and 15.78 kg m−2 for HL, for A and B horizons, respectively. Carbon stock values were markedly influenced by regional climate, type of vegetation, and land use. The usually neglected pool of organic carbon in B horizons of deeply weathered Latosols accounts for between 42–76% of the total C stocks.