EVALUATION OF MICROBIAL INOCULANTS FOR ENHANCING GRAIN LEGUME PRODUCTION IN THE SUDAN AND GUINEA SAVANNA ZONES OF NIGERIA

This experiment was conducted in Kano (Sudan savanna) and Bauchi (Guinea savanna) states of Nigeria between 2015 to 2016 cropping seasons to assess microbial inoculants use for soybean and groundnut production in northern Nigeria. The experiment in each location was a randomized complete block design (RCBD) with seven treatments and replicated four times. Four rhizobia inoculants were tested on soybean (TGX 1835) and groundnut (SAMNUT 24) in the two agro-ecological zones to monitor their performance and their ability to establish symbiotic relationship and nodulate soybean and groundnut. The treatments for soybean were; Legume fix, Alosca, nitrogen, cattle manure, Legume fix + cattle manure, Alosca + cattle manure and control whilst those for groundnut comprised Histick, Biofix, nitrogen, cattle manure, Histick + cattle manure, Biofix + cattle manure and control. Most probable number (MPN) method was used to assess the number of rhizobia cells in the inoculants used for the field experiment. During the 2016 cropping season, maize (SAMMAZ 14) was planted to evaluate the residual effect of microbial inoculants and treatments on maize grain yield. Results showed that, the inoculants contained enough number of viable rhizobia strains to inoculate legumes. The study showed that in the Sudan and Guinea savanna agro-ecological zones, inoculation resulted in significant soyabean yield increments compared to the control. However, the application of nitrogen fertilizer had no significant effect (P > 0.05) on grain yield in both agroecologies. In the Sudan savanna, increased nitrogen fixation values of 173.90, 101.64, 56.16 and 40.40% were obtained for Legume fix, Alosca, Legume fix + cattle manure and Alosca + cattle manure over the control. The same nitrogen fixation trend was observed in the Guinea savanna zone. Combination of inoculants with 4 tonnes ha-1 cattle manure gave higher soybean grain yield than sole inoculant in the Sudan savanna. In the case of groundnut, it was observed that, inoculated plots produced higher grain yield, even though not significantly different from the control. In soybean inoculants influenced BNF significantly (P < 0.05) when compared to control in both study locations. In the groundnut field, Biofix produced higher nitrogen fixed than all treatments in the Sudan savanna, while in the Guinea savanna no significant differences (P = 0.67) were observed between the treatments and the control. However, inoculated plots had higher nitrogen fixation than the control. Legume fix and Alosca performed well under soybean field while Histick and Biofix performance was low under groundnut fields in both locations. Economic analysis showed that, Legume fix was the most economically viable treatment having the highest net benefit in both locations under soybean, while under groundnut, the usage of inoculants was not economically viable due to low net benefit. It can thus be concluded that, application of Legume fix and Alosca in study both locations under soybean resulted in yield increment while the result in groundnut fields showed little response in Histick. Results of the second-year study showed that residual effect resulting from inoculation enhanced maize yield on the soybean and groundnut fields in both study locations. It is recommended that farmers should use inoculants in combination with cattle manure for better yield.

Source: KNUST