Response of soybean (Glycine max) to Rhizobia inoculation, mineral nitrogen and inoculation amendment at the two agro ecological zones of northern Nigerian savannah

For sustainable agriculture nitrogen must be adequately supplied because it is the most limiting major nutrient required by all living plants. This experiment was conducted at the two ecological zones, Sudan savannah in Kano State and Guinea savannah in Bauchi state of Nigeria during the 2016 cropping season. The design of the experiment was Randomized Complete Block Design (RCBD) with seven treatments and four replications in each site. The treatments were; legume fix, alosca, 50 kg N ha^-1, cattle manure, legume fix + cattle manure, alosca + cattle manure and control. The result showed that Legume fix had the highest grain N uptake (90.51 kg N ha^-1) which differed significantly (P≤0.001) from the rest of the treatments. At Guinea savannah legume fix gave the highest N uptake value (95.53 kg N ha^-1) which was significantly different from all treatments except legume fix + cattle manure. However, 50 kg N ha^-1 gave the least (48.64 kg N ha^-1) even lower than the control and differs significantly with the rest of treatments (P≤0.001). Legume fix gave the highest P uptake value (9.66 kg P ha^-1) which significantly differed from all other treatments. At Sudan savannah, significant differences (P ≤ 0.001) occurred between some of the treatments. Alosca + cattle manure recorded the highest K uptake (49.99 kg K ha^-1). Result for the fixed N in the Sudan and Guinea savannahs soybean field revealed a significant difference between the treatments and the control.