Evaluation of four microbial bio-effectors for growth promotion and nutrient acquisition in bambara nut Vigna subterranea (L.) Verdc. (Fabales: Fabaceae) without mineral fertilization

This study seek to evaluate the potential of four BEs (Azotobacter, Azospirillum, Rhizobium and Arbuscular mycorrhizae fungi (AMF)) without complementary inorganic fertilizer in promoting plant growth and nutrient uptake in contrasting soil types. Field studies set up in completely randomized design (CRD) were conducted in Southwestern Nigeria using bambara groundnut Vigna subterranea (L.) Verdc. (Fabales: Fabaceae) as test crop sown on a sandy loam and clay loam alfisol. Result indicates that performance of inoculated BEs in improving bambara nut growth and nutrient uptake did not differ according to soil types. Promising results were obtained with all BEs with Rhizobium, AMF and Azospirillum showing exceptional performance respectively across all measured parameters. These BEs are recommended for adoption by local farmers in the study area to optimize bambara nut performance with the aim of reducing dependence on inorganic fertilizers and improving fertilizer use efficiency.