Soil organic carbon stock and litter mass in silvopastoral systems with Eucalyptus

The objective of this study was to evaluate the soil organic carbon stock and litter mass in silvopastoral systems (SSP) implemented with Urochloa decumbens and different Eucalyptus spatial arrangements. The SSP was implemented in 2008 with the spatial arrangements of (3 × 2) + 20 m (434 trees ha⁻¹), (2 × 2) + 9 m (909 trees ha⁻¹) and 9 × 2 m (556 trees ha⁻¹) formed by the Eucalyptus cultivars GG100, I144 and VM 58. Soil samples at 0 to 20 and 0 to 40 cm depths were collected in SSP in 2011 and 2015 to determine soil organic carbon stock. The soil organic carbon stock was 38.5% higher in 2015 compared to 2011 (111 vs. 80.7 Mg ha⁻¹), which represented an annual sink of 6.22 Mg ha⁻¹ and indicates an increase in carbon stock over years. Litter mass was greater under the canopy than between trees, probably due to the greater drop in biomass in this location. The silvopastoral systems showed similar volumes of litter and soil organic carbon, which indicates that the evaluated arrangements have similar capacities to store carbon.