Abstract:Compatible rhizobia populations are seldom available in soils where soybean has not been grown before.Inoculating soybean seeds with superior rhizobia strains is necessary for nodulation and nitrogen fixation. Ironically, many commercial agricultural products (biological and chemical) claim increases in crop productivity but their efficacy cannot be guaranteed. Thus, three separate on-station trials (Manga, Kpongu and Nyankpala) were conducted at the experimental fields of CSIR-Savannah Agricultural Research Institute (SARI), to ascertain the effectiveness of some commercial microbial inoculant and micronutrient fertilizer for improvement of soybean productivity in the Northern savannah zones of Ghana. Four treatments were used for each study site; Control, Teprosyn Mo, Legumefix and Teprosyn Mo+Legumefix which were laid out in a Randomised Complete Block Design (RCBD) with three replications. Experimental plots measured 4.5 m x 4.5 m. A significant (P < 0.05) response of soybean nodule dry weight to Legumefix was observed in Kpongu and Manga but not Nyankpala. At harvest, Teprosyn Mo+Legumefix, Legumefix and Teprosyn Mo treatments increased soybean grain yield by 205.62%, 135.54% and 110.24% respectively over the control in Manga. In Nyankpala, the application of Legumefix and Teprosyn Mo+Legumefix increased soybean grain yield significantly by 22.43% and 42.10% respectively relative to the control while no significant response was observed in grain yield among treatments at Kpongu. The combined application of Teprosyn Mo+Legumefix was the most economically viable among the treatments (VCR = 2.65).