Drought effects on soil organic carbon under different agricultural systems

Abstract Drought is a natural hazard occurring with increasing frequency due to climate change. Drought events reduce soil water content and also soil organic carbon (SOC) content, with negative impacts on crop development and food security. This study investigates the impact of drought on SOC dynamics in agricultural systems and the influence of water availability and farm management practices in these impacts. The manuscript is a systematic review, based on Scopus database for scoping the literature on the topic. A total of 283 records were retrieved, but only 16 papers were relevant for the review. The main findings are: (1) water plays a key role in regulating SOC mineralization due to its impact on dynamics of soil microbial communities, necessitating further research on water management to mitigate carbon losses during drought; (2) different agricultural systems can have differing impacts on SOC under drought conditions depending on crop type (e.g. pastures are more resilient than arable systems) and farm management practices; and (3) SOC loss generally occurs after a drought event, regardless of farm management regime, but the contribution of drought to this loss requires further research. Best management practices, such as cover cropping and soil amendment, can minimize SOC losses, but further research is required to optimize these practices in counteracting the effect of drought. A better understanding of the effects of drought on SOC dynamics, and of short-term and long-term ways to mitigate these effects, is important to ensure soil health and crop productivity.