Effect of Rhizobium japonicum and phosphorus on nutrient uptake and yield of soybean (Glycine max) in an Ultisol of Manipur hills

An experiment was conducted during 1994 and 1995 to study the effect of Rhizobium inoculation and phosphorus fertilization on soybean [Glycine max (L.) Merr.] production in an acid hill Ultisol of Manipur. Rhizobium inoculation increased the soil-Rhizobium population and nitrogen fixation. It increased the grain yield and nodule weight by 35-43%. It also showed an additive residual effect in 1995 by increasing the yield by 15%. P fertilization increased the nodule weight, grain yield, N and P uptake and nitrogen content of the soil significantly. Rhizobium and phosphorus interaction was also significant for grain yield, and N and P uptake only in 1995, whereas nodule weight increased significantly during both the years. Phosphorus-use efficiency was maximum with 13 kg P/ha level along with inoculation, but total grain yield (2340 kg/ha) and net return (Rs 16704) were maximum with 26 kg P/ha level along with inoculation.