Effects of climate-smart agricultural practices on crop yields, soil carbon, and nitrogen pools in Africa: a meta-analysis

Abstract

Climate-smart agriculture (CSA) practices have been advanced as an alternative to conventional farming practices due to their importance in climate mitigation and soil quality improvement, while also enhancing food production. However, few studies have quantitatively investigated the effects of a range of CSA practices on crop yield, soil carbon, and nitrogen pools. This study adds to this limited body of work by synthesizing such studies and evaluates the effect of individual and combinations of widely implemented CSA practices in Africa—green manure (GM), conservation tillage (no-tillage, reduced tillage), and crop residue retention (CR)—on food crop yield, soil organic carbon (SOC) concentration, and soil total nitrogen (TN). This study conducted a meta-analysis of results reported in 60 peer-reviewed articles to examine the effects of CSA management (GM, CR, and conservation tillage) on crop yield, SOC concentration, and soil TN in Africa. The implementation of CSA practices significantly increased crop yield and SOC concentrations (mean effect 9.2% and 14.7%, respectively), although no significant change was evident in soil TN. In terms of yield increase, GM was the most effective practice, increasing yield by 63.5%, followed by CR (5.8%). Conservation tillage and CR increased SOC by 16.4% and 13%, respectively, but no significant difference was observed with GM. Further analysis suggested that integrating CSA practices (conservation tillage and GM; conservation tillage and CR) had a more pronounced effect on both SOC concentration and yield under lower nitrogen fertilizer levels. Our meta-analysis showed that CSA management resulted in higher yields and SOC concentrations, thus suggesting the importance of CSA practices in enhancing food production and climate mitigation in Africa. It also highlights the potential of the integration of CSA practices to improve SOC and TN pools and consequently crop productivity.