Projected climate change effects on soil carbon dynamics in Brazilian dryland agroecosystems under management intensification

Brazilian dryland agroecosystems are increasingly vulnerable to climate change, with rising temperatures and intensified aridity threatening soil functioning and long-term agricultural sustainability. Soil organic carbon (SOC) is a central indicator of soil health and resilience in these environments, yet its long-term response to interacting climate and management drivers remains uncertain. This study applied the process-based DayCent model to evaluate SOC dynamics from 2024 to 2100 under the current climate and two future scenarios (SSP2–4.5 and SSP5–8.5). Simulations were performed for three representative dryland regions in Brazil (Betânia do Piauí, Petrolina, and Sobral) covering contrasting soil textures, climatic conditions, and land-use systems, including native vegetation, conventional agriculture, and intensified management strategies such as fertilization, no-tillage, crop–livestock integration, and crop–livestock–forestry integration. Model calibration using field-measured SOC and nitrogen stocks demonstrated good agreement with observations. Results showed that land-use change from native vegetation generally reduced SOC stocks, particularly under low-input and disturbance-intensive systems. In contrast, management intensification, especially the combined use of fertilization and no-tillage, substantially increased SOC under the current climate, with gains reaching up to 36–46% relative to conventional systems. However, future climate projections indicated SOC declines across all sites, with greater losses in coarse-textured soils and under the high-emission SSP5–8.5 scenario. Although integrated agricultural systems mitigated SOC losses more effectively than conventional practices, they were insufficient to fully counteract climate-driven declines by the end of the century. These findings highlight that conservation-oriented intensification can enhance SOC resilience, but additional adaptation strategies will be required to sustain soil carbon stocks.