ABSTRACT:

The experiments were conducted at the Teaching and Research Farm, Faculty of Agriculture, Shabu – Lafia Campus, Nasarawa State University, Keffi, during 2018 and 2019 cropping seasons to evaluate the separate and combined effects of legume inoculant and biochar on yields of soybean. The experiments were laid in Randomized Complete Block Design (RCBD). Biochar at the rates of 0, 4, 8 and12 tons/ha was incorporated into the ridges at planting. Four seeds of soybean were planted as uninoculated (without legume inoculant) and inoculated (coated with legume inoculant). All data collected were subjected to analysis of variance (ANOVA) using GENSTAT Statistical Package while least significant different (LSD) was used to separate treatment means at 5% probability. The results showed that inoculated plots recorded significantly (P<0.05) the heaviest weight per 100 seed (15.4 and 14.9g)and grain yields (1201.7 and 1212.3kg/ha) against the uninoculated plots (14.0 and 12.5g) and (751.0 and 760.0kg/ha) in 2018 and 2019. The results also showed that biochar at the rate of 8 tons/ha recorded the heaviest weight per 100 seed (16.6 and 14.9g) and grain yields (1304.0 and 1316.7kg/ha) against the other rates of biochar in both cropping seasons. The combination of biochar at the rate of 8 tons/ha with inoculants recorded the heaviest weight per 100 seed (18.4 and 16.6g) in 2018 and 2019 and grain yield (1420 kg/ha) in 2018.However the highest dose of biochar (12 tons/ha) applied did not necessarily influenced and increased soybean yield parameters tested.