Biofertilizers in production and protection of staple cereal crops in semi-arid regions of sub-Saharan Africa

Biofertilizers are proposed as practical alternatives for smallholder farmers in semi-arid sub-Saharan Africa (SSA). However, the role and efficacy of bacterial and fungal biofertilizers in cereal crops, sometimes accompanied by organic nutrient resources, remain insufficiently synthesized in literature. We conducted a structured literature review using the search terms “biofertilizers,” “bioinoculants,” “microbial fertilizers” and crop terms “cereals,” “maize,” “sorghum,” “wheat,” “rice” in Google scholar and Scopus resulting in 52 studies published between 2017 and 2023 that met predefined inclusion criteria. This enabled assessment on which native microbial species and existing farm-based biofertilizer resources are utilized, the status of commercial and on-farm production in SSA, and the crop, soil microbial, organic matter, and pest management impacts. Across included studies, 68% and 54% reported positive effects on crop biomass and yield, respectively, with higher efficacy for mycorrhizal inoculants compared to bacterial biofertilizers, and lower rates of positive response for abiotic stress tolerance and microbial colonization. A small fraction of studies assessed impacts on soil microbial biomass, soil carbon cycling, or cereal pest resistance. We highlight the need for field-based and mechanistic studies on soil microbial impacts, plant growth and resistance to abiotic and insect pests in degraded soils of semi-arid SSA cereal systems.