Soil carbon dynamics in Brazilian Atlantic forest converted into pasture-based dairy production systems
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2021-03-04
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Wiley-Blackwell
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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.
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Agronomy Journal. Hoboken: Wiley, 14 p., 2021.