TOTAL ORGANIC CARBON (TOC) AND PYROGENIC CARBON (PC) STOCKS UNDER DIFFERENT LAND USES IN THE CERRADO

Soil carbon stock is a key factor for mitigating climate change, especially in the Cerrado, where soil management may significantly influence the carbon stock, given its historical burning. Pyrogenic Carbon (PC) is a refractory organic matter fraction, with high stability and long residence time. Investigating PC stocks from biomass burning and labile organic matter (SOM) under different management systems is essential, as PC behaves differently from labile fractions, influencing soil carbon dynamics and stability. This study aimed to evaluate total organic carbon (TOC) stock, labile and refractory TOC and PC, in soils under different land uses in a Cerrado area, comparing Integration Crop-Livestock-Forestry (ICLF) and pastures with the Native Forest area as a reference. Samples were collected at Fazenda Pontinha, Bandeirantes, MS, Brazil, from profiles up to 1 meter deep in five systems: Native Forest (NF), Managed Pasture (MP), Unmanaged Pasture (UP), Integration Crop-Livestock (ICL) and Integration Livestock-Forestry (ILF).PC content was determined by the CTO-375 thermal combustion method: Oxidation of the labile fraction at 370°C for 24 hours with oxygen fluxes in a muffle furnace (Nabertherm), followed by loss-on-ignition analysis at 550°C for 1 hour to determine labile and refractory carbon fractions. Elemental Carbon Analyzer analysis is ongoing for comparison. The highest SOM stock was found in the surface layer (0-5 cm) in MP system (2.85 mg C ha⁻¹), meanwhile ILF system showed less variability among layers. The ICLF systems had the highest TOC stock across all layers, with ILF reaching 2.17 mg C ha⁻¹ in the surface layer as well. Regarding PC, ICL had the highest value (7.48 mg C ha⁻¹), whereas NF had 4.16 mg C ha⁻¹ (40-70 cm). Notably, this was the only layer where ICLF systems did not show the highest PC stocks, reinforcing their potential for carbon retention. ICLF systems enhance soil refractory carbon stocks, promoting carbon stability in Cerrado areas. The findings suggest conservation soil management plays a vital role in climate change mitigation. Adopting ICLF systems aligns with SDG 13 (Climate Action) by supporting soil carbon retention, SDG 2 (Zero hunger and sustainable agriculture) by improving soil fertility and productivity, SDG 12 (Responsible Consumption and Production) by promoting sustainable land use, and SDG 15 (Life on Land) by supporting land restoration and biodiversity conservation. Future studies should integrate radiocarbon dating to assess PC residence time under different management practices.