Effects of Native Rhizobia on Soybean [Glycine max (L.) Merrill] Production and Soil Properties in Daloa, Center-West of Côte d’Ivoire

The field experiment study was conducted at the experimental station of Jean Lorougnon Guede University in Daloa to evaluate the potential effects of native rhizobia strains on soybean production and soils properties. The experiment was layout in a randomized complete block design with three replications. The treatments include seven native strains, one exotic strain (Bradyrhizobium japonicum IRAT FA3), one synthetic fertilizer NPK 12-22-22 formulation and one negative control (no fertilizer, no inoculation). Agronomic parameters (plant height, plant dry biomass, nodule number plant-1, pod number plant-1, pod weight plant-1, seed yield ha-1) and soil parameters (pH, total nitrogen, orgnanic carbon, organic matter and available phosphorus) were measured. Results showed that all tested native rhizobia enhanced nodules number, plant growth and soybean yield as compared to negative control. Among these native rhizobia, RSC119 and RSC504 induced more nodules than the introduced strain B. japonicum IRAT FA3. RSC119, RSC309 and RSC508 produced more pods and seed yield than the introduced strain B. japonicum IRAT FA3 and the synthetic fertilizer NPK 12-22-22. RSC508 induced the highest pods number plant-1 (102 pods) and seed yield (4.2 t.ha-1). Moreover, these local bacteria had positive effects on soil properties following the soybean’s harvest. Among these bacteria, RSC119 enhanced mostly total nitrogen, organic matter and available phosphorus, then RSC508 significantly reduced soil acidity. This study therefore suggests that local rhizobia are effectiveness and could be use as inoculum to improve soybean productivity and soil properties restoration.