Evaluation of an improved inoculation technology using Bradyrhizobium japonicum USDA110 on peat and charcoal for the cultivation of soy bean plant

Nutrient paucity in the soil poses challenge to global production of food. The use of synthetic nitrogen fertilizers to boost crop yield is a recurrent farming practice, despite their unfavourable effects and hazard to the environment and human population. This study was aimed at developing an environmental friendly, low cost inoculation technology for the cultivation of soybeans. Laboratory approach was used in the production of the biofertilizer, which started with biochemical characterization of the Bradyrhizobium japonicum USDA110, the Rhizobium species that has been known to nodulate soybean plant effectively. This organism was positive to bromothymol blue, catalase and oxidase, but negative to caesinase, citrate, lipase, lysine decarboxylase and starch hydrolysis. Volume of Bradyrhizobium japonicum USDA110 was multiplied in a process called scale-up, using Yeast Mannitol Broth as the growth medium, and other steps taken were; inoculation of the peat and charcoal bags with the broth, curing, quality control checks and cultivation of soybean, some treated with the biofertilizer, and others cultivated without treatment. The height of the cultivated soybean plants was 37,10±2.94 cm, 35.00±1.27 cm and 17.70±1.33 cm for the peat carrier, charcoal carrier and untreated seeds respectively, and the number of root nodules formed are 24.00±1.00, 23.00±1.00 and 5.00±1.00 and for peat carrier, charcoal carrier and untreated seeds respectively. This work reveals that Bradyrhizobium japonicum USDA110 is effective for maximum nodulation and corresponding increase in yield for soybean plants, with peat being the best carrier for the Rhizobium. In addition, charcoal can also be used as an alternative carrier in the absence of peat or when sourcing for peat is expensive. The present investigation is a promising approach to consider the optimum method for establishing a purposeful symbiotic relationship between soybeans and the Rhizobium, and these findings allow a new scope for extensive research in Agricultural Biotechnology.