Adoption of soil fertility improvement technologies in West African Sahel: A systematic review of advances, barriers and drivers

Context In addressing the challenge of low soil fertility in mixed crop-livestock systems in West African Sahel, technologies have been promoted over many decades with mixed results in terms of adoption by smallholder farmers. Understanding the current state of knowledge and challenges to the adoption of soil fertility technologies is crucial to address constraints to adoption and to identify enablers. Objective The objectives of this study were to review the current state of knowledge, knowledge gaps, barriers and drivers of adoption of soil fertility improvement technologies in West African Sahel, and to synthesize lessons and recommendations from the literature. Methods This study is a systematic review following the Preferred Reporting Items For Systematic Reviews and Meta-Analyses (PRISMA) protocol to identify a collection of published documents that pertain to the adoption of soil fertility improvement technologies in West African Sahel. The review included 114 publications on adoption of soil fertility technologies in West African Sahel. Results and conclusions The results showed that soil fertility improvement technology with the highest number of publications on adoption was mineral fertilizer, followed by manure application, zai, mulching, and improved crop varieties. Results further showed that barriers and drivers of adoption in the region are mainly socio-economic and institutional-related. Gaps in knowledge on adoption of soil fertility technologies identified from this review included incoherency in definition of adoption in many empirical studies, non-inclusion of credit facilities and agricultural digital services in most technology packages, and paucity of studies on the influence of gender, institutional and policy related issues, and risks on adoption. Future studies should address these gaps for a better understanding of dynamic processes of adoption and to enhance adoption, thereby improving agricultural productivity and livelihoods of smallholder farmers in mixed crop-livestock systems in West African Sahel. Significance This study addresses the paucity of review studies on adoption of soil fertility improvement technologies in West African Sahel. It also contributes to critical evaluation of accumulated knowledge on adoption of soil fertility and proposes recommendations to inform and guide key stakeholders in the agricultural sector in the region to enhance adoption thereby improving agricultural productivity of smallholder farmers.