Soil carbon dynamics in Brazilian Atlantic forest converted into pasture‐based dairy production systems

The conversion of Brazilian tropical forests into pastureland was a complex process, potentially harmful to the environment, heightened by degraded grazing systems that did not ensure sustainability and affected the ecosystem resilience. This study was conducted to determine the long‐term changes in soil C stocks in native forest (FOR) converted to pasture‐based dairy systems (continuous grazing system with low stocking rate–CLS; rotational grazing system with high stocking rate–RHS). Soil samples were analyzed for texture, C, organic matter (OM), bulk density (BD), C stock, and carbon accumulation rates (CAR) in 0‐to‐5‐, 5‐to‐10‐, 10‐to‐20‐, 20‐to‐30‐, 30‐to‐40‐, 40‐to‐60‐, 60‐to‐80‐, and 80‐to‐100‐cm depths in six trenches. Bulk density was higher in RHS compared with CLS and FOR in most of the soil layers. In the 0‐to‐5‐cm layer, C and OM were greater in CLS. Carbon contents were similar in RHS and FOR, whereas OM was higher in FOR. Intensification increased BD, reduced OM, and did not affect C content in the 0‐to‐5 cm layer. For all treatments, C stock and CAR were higher in the 0‐to‐100 cm (136.73 Mg ha −1 and 0.4252 Mg ha −1 yr −1 ) than the 0‐to‐30 cm (61.79 Mg ha −1 and 0.0447 Mg ha −1 yr −1 ) layer. The soil C stock remained equal for both pastureland and presented a positive CAR in relation to the forest, working as C sinks. The RHS presented the greatest forage yield, carrying capacity and milk yield. This management resulted in a land‐saving effect of 2.7 ha for each hectare of high intensified pasture.