GROWTH AND YIELD RESPONSE OF SCREENED SOYBEAN (Glycine max L. MERRILL) GENOTYPES TO FERTILIZATION AND RHIZOBIA INOCULANTION IN NORTHERN GHANA

Abstract

Soybean remains an important crop for the sustenance of livelihoods of resource-constrained farmers in northern Ghana. However, yield of the crop has continuously remained low due to poor soil fertility and low productivity. A two-phase experiment was carried out during the 2019 cropping season to evaluate the growth and yield response of screened soybean genotypes to nitrogen, phosphorus and rhizobia inoculation. In the first phase, growth and yield of 100 selected genotypes were evaluated under optimum phosphorus fertilization using the lattice design. In the second phase, 3 best performing genotypes (N19, N119, N135), selected in phase one together with a known variety (Jenguma) were accessed for growth and yield under phosphorus, nitrogen and inoculants using a 4 (genotype) x 7 (nutrient regime) split plot design. The nutrient regimes were sole triple super phosphate (TSP), sole inoculant, sole booster nitrogen, TSP + booster nitrogen, TSP + inoculant, TSP + booster nitrogen + inoculant and a control (no fertilizer). Each treatment was replicated three times. Data collected were subjected to analysis of variance and means separated at 5% probability using the least significant difference. Results show a significant (P = 0.032) interaction effect between genotype and nutrient regime on grain yield. Jenguma, treated with TSP + inoculant recorded the highest yield of 4 t/ha, followed by Jenguma variety treated with TSP + inoculant + booster nitrogen (3.9 t/ha), and genotype (N135) treated with TSP + nitrogen (3.7 t/ha), while genotype (N19) without treatment (control) recorded the least grain yield. The high yield obtained for inclusion of P, N and inoculants exceeded what is documented for northern Ghana (1.5 t/ha). Therefore, it is recommended for farmers to include P, booster N and inoculants in cultivation of the Jenguma variety, and N135 genotype. Based on economic cost analyses, farmers stand to achieve higher profit upon application of sole TSP.