Agriculture intensification in subtropical crop systems and its potential to sequester carbon in soils

Abstract

Soils are the third largest carbon pool on Earth. This underscores the significance of soil carbon sequestration as a prominent strategy for global climate change mitigation, especially in countries with strong agricultural backgrounds. Numerous studies have demonstrated the effectiveness of conservation agriculture in SOC sequestration. However, little is known about how intensified and diversified crop systems affect SOC dynamics. The relationship between crop intensification, diversification and carbon storage is intricate and context-dependent, contingent upon factors such as crop varieties, management practices, local climate, and soil conditions. This study, conducted in Southeastern Brazil, investigates the impact of crop intensification and diversification systems on SOC sequestration and assesses the current capacity to predict SOC increase using Century model. We found that crop system intensification promoted SOC increase from 2020 to 2022, especially when associated with diversification including legumes and brassicas during the winter (from 54.76 to 56.66 Mg ha⁻¹). Although the systems do not differ statistically, the difference average between systems is growing yearly (from 0.7 to 4.1 Mg ha⁻¹ from less to more intensified and diversified system), the experiment’s short period can be a reason for these findings. The predications overestimated SOC increase rate for less intensified systems and underestimated SOC increase rates for more intensified systems. Adjustments in future models regarding SOC stabilization in subtropical soils minerals like Fe and Al oxides may reduce this prediction gap. Our study also contributes to the ongoing discussion on soil carbon dynamics and its pivotal role in mitigating climate change.