Effects of Bradyrhizobium japonicum on Some Chemical Properties of Ferralsols under Soybean (Glycine max (L.) Merr.) Cultivation

This study was conducted on acidic soils in two different agro-ecological zones in order to evaluate the influence of Bradyrhizobium japonicum on soil chemical properties in the Upper-Katanga (DR Congo). A split plot design with three replicates was installed in two sites. The main plots included three strains of Bradyrhizobium japonicum plus the untreated control and four soybean varieties in subplots. Seed inoculation was performed in the shade and sown on the same day. The results showed that Bradyrhizobium strains did not influence soil pH, Nitrogen, C: N ratio and organic matter neither at flowering nor at harvest. However, total and available phosphorus (P) were influenced by the different treatments at harvest in Kanyameshi site. The strain S1 induced the highest average of total and available P whereas, the strain S2 had the lowest value of total P, and S3 induced the lowest content in available P. By comparing the timing of soil sampling at flowering and harvesting, the Student test revealed significant differences in pH, total nitrogen, C: N ratio, organic matter and available P indicating that soil chemical properties was improved at harvest and are only partially influenced by applied Bradyrhizobium strains.