Influence of Rhizobium and NPK on Some Microbial Properties and Yield of Soybean (Glycine max L.) in Calabar, Cross River State, Nigeria

This study evaluated the effects of Rhizobium inoculation and organic substrate amendments on soil properties and the growth performance of soybean under controlled conditions. A factorial experiment arranged in a Completely Randomized Block Design (CRBD) was conducted using different substrate treatments and inoculation levels. Soil samples were analyzed before planting, and data were collected on selected soil chemical properties as well as plant growth parameters over a period of twelve weeks. Statistical analysis was carried out using analysis of variance (ANOVA), and significant means were separated using Duncan Multiple Range Test (DMRT) at 5% probability level. The results revealed that the application of Rhizobium inoculation and organic substrates significantly improved soil fertility indicators, including soil pH, organic matter content, and essential nutrients. Similarly, soybean growth parameters such as plant height, number of leaves, and biomass production showed significant improvement under treated conditions compared to the control. The interaction effects between Rhizobium inoculation and substrate types were also significant, indicating the synergistic role of biological and organic inputs in enhancing soil productivity and crop performance. The study concludes that the combined application of Rhizobium inoculation and suitable organic substrates can serve as an effective strategy for improving soil fertility and soybean productivity. It is therefore recommended that farmers adopt integrated soil fertility management practices involving biofertilizers and organic amendments for sustainable agricultural production.