Soil carbon sequestration affected by no-tillage and integrated crop-livestock systems in Midwestern Brazil

摘要

Conservation management systems can improve soil organic matter stocks and contribute to atmospheric C mitigation. This study was carried out in a 15-year long-term field experiment established on a tropical Oxisol in Dourados/MS, Brazil, to assess the potential of tillage systems [conventional tillage (CT), no-tillage (NT) and no-tillage integrated crop-livestock (ICL)] for mitigating atmospheric C. For that, the soil organic carbon (SOC) accumulation in the 0-100 cm depth and the C equivalent (CE)costs of the different management systems were taken into account for comparison with the CT. More SOC accumulation was observed in NT and in ICL systems because of the lesser oxidative environment compared to CT. SOC accumulation rate in NT was 0.21 Mgha~(-1) yr~(-1) higher in the 0-30 cm layer, and lower rates were observed below 30-cm depth. ICL system accumulated three times more SOC in the 0-30 cm layer than NT. Probably, this greater SOC accumulation in ICL system is due to greater amounts of forage root mass compared to crops like soybean, wheat, oat, which were cultivated in NT systems. SOC accumulation rates increased by 30% when SOC was assessed up to deep layers (i.e. 100 cm depth) as the result of carbon addition in deep layers by tropicalforage. These results indicated that ICL system can be a better strategy to provide C mitigation in Midwestern Brazil compared to no-tillage alone.