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Rhizobia inoculation with effective strains is an environmentally friendly approach for enhancing nodulation and yield of legumes. To obtain an ideal strain for inoculant production, the strain's performance must be matched to the environmental conditions. A 2 × 9 cross-factorial experiment laid in a randomized complete block design with three replications on farmers' fields in the northern part of Ghana was set up to evaluate the rhizobia's performance. The factors were groundnut varieties (Chinese and Samnut 22) and nine strains consisting of five native rhizobia (KNUST 1001, 1002, 1003, 1032, and 1031), two commercial strains (Biofix and BR3267), and a positive (N+) and absolute control (N–). In addition, the population of the strains was assessed after a cropping season. The strains' performance on groundnut was location and variety dependent. At Cheshegu, KNUST 1031 and 1002 significantly increased seed yield of the Chinese variety compared to other strains; however, KNUST 1031 elicited a 24% yield increase while KNUST 1002 caused a 16% yield increase over the control. Strain KNUST 1031 increased the seed yield of the Chinese variety by 24% while KNUST 1002 increased the seed yield of Samnut by 16%. Only KNUST 1002 elicited a significant seed yield increase in Samnut 22 at Cheshegu. At Binduri, strain KNUST 1003 significantly increased the seed yield of the Chinese variety by 35% relative to the control. Samnut 22 did not show a clear preference for any of the strains. The Chinese variety did not show a clear response to the strains at Tanina. However, Samnut 22 responded to KNUST 1002 as it increased seed yield by 45% relative to the control. On average, the seed yield at Tanina (846.15 kg ha−1) was less than the seed yield recorded at Binduri (1,077.66 kg ha−1) and Cheshegu (1,502.78 kg ha−1). Inoculation with strains KNUST 1002, 1003, and 1031 was all profitable under the current experimental conditions as they recorded value cost ratios (VCRs) above the threshold of 3–4. The study has shown that strains KNUST 1002, 1003, and 1031 have the potential to be used in inoculant formulation to increase groundnut production and enhance the income of smallholder groundnut farmers in northern Ghana.

Inherently low concentrations of soil nutrients and erratic rainfall pattern in sub-Sahara Africa limit soybean response to rhizobia inoculant and P-fertilizer. The study was conducted to: (i) improve soybean response to rhizobia inoculation and P-fertilizer through the addition of organic manure; (ii) enhance rain water use efficiency and (iii) determine the economic viability of combined application of the three factors in soybean cropping systems in the Northern region of Ghana. A factorial experiment with two levels of rhizobia inoculant, two levels of Phosphorus, two different kinds organic manure [fertisoil (a commercially prepared compost from urban waste, rice husks, of poultry manure and shea butter waste) and cattle manure] and a control arranged in randomized complete block design with three replications was established on farmers' fields. The combined application of rhizobia inoculant, P-fertilizer, and organic manure markedly increased nodulation, shoot biomass, haulms, harvest index (HI), P agronomic efficiency (P-AE), and rain water use efficiency (RUE) compared to the control. The combined application of rhizobia inoculant, P-fertilizer, and fertisoil increased grain yield by four-folds whereas the combined application of rhizobia inoculant, P-fertilizer, and cattle manure increased grain yield by three- folds. Harvest index, P-AE, and RUE were relatively higher with the fertisoil treatment combinations than with the cattle manure combinations and the control treatment. The application of rhizobia inoculant, P-fertilizer in combination with fertisoil was profitable with VCR of 2 as compared to the combination of cattle manure which had a VCR of 0.40. The results showed that fertisoil offers a better option of improving soybean response to rhizobia inoculant and P-fertilizer; and has the potential to enhance rain water use efficiency. However, the long term benefit must be quantified.