CARBON STOCK IN SOIL AND ROOTS IN BEEF CATTLE PRODUCTION SYSTEMS

Soil and root carbon stocks are crucial for evaluating environmental quality and the sustainability of production systems. This study aimed to assess soil carbon stock (SCS), root carbon stock (RCS), and dry matter (DM) in pasture systems under different intensification levels. The experiment was conducted at Embrapa Southeast Livestock, in São Carlos (SP), across two soil types with different clay textures, evaluating four systems: degraded Urochloa decumbens pasture without fertilization (DP0); rainfed U. brizantha under moderate-intensity management with fertilization of 200 kg N ha⁻¹ year⁻¹ (RP200); rainfed Megathyrsus maximus with high stocking and 400 kg N ha⁻¹ year⁻¹ (RP400); and irrigated M. maximus with high stocking and 600 kg N ha⁻¹ year⁻¹ (IP600). Carbon content was measured in the 0–30 cm soil layer, and stocks were calculated and analyzed using ANOVA followed by Tukey’s test (5%). SCS was highest in RP200 (58.4 Mg C ha⁻¹), differing from RP400 (46.4 Mg C ha⁻¹) and DP0 (37.0 Mg C ha⁻¹), associated with lower soil bulk density. IP600 (55.1 Mg C ha⁻¹) differed only from DP0. DM was highest in DP0 (16.4 Mg ha⁻¹), suggesting a compensatory response to soil physical stress. RCS was highest in DP0 (6.6 Mg C ha⁻¹), reflecting greater root carbon input and stabilization in less intensified systems. The results indicate that moderate intensification levels, such as in RP200, promote soil carbon conservation, whereas degraded systems, such as in DP0 enhance carbon allocation to roots and dry biomass as an adaptive response to adverse soil physical conditions.