Effects of Nitrogen Fertilizer and Rhizobium on Nodule Growth and Yield of Soybean (Glycine max L.)

Soybean production in Indonesia needs to be improved to fulfill 9.15% of its demand. This causes the level of soybean imports in Indonesia to be very high. Production enquities and wants encourage the intensification of soybean cultivation. Intensification efforts are carried out with appropriate fertilization. Soybeans are a plant belong to Leguminaceae family so that they have a symbiotic relationship with many microorganisms, including rhizobium. The prime importance of conduct this experiment was to find out the impact of nitrogen fertilizer and rhizobium on nodule growth and soybean yield.

The experiment was conducted in two-factors in factorial completed randomized design. The first factor was the doses of nitrogen fertilizer (0, 50, 100 and 150 kg ha^-1). The second factor was Rhizobium inoculation (control, inoculant and soybean used soil). Data analysis was carried out by analysis of variance, if there is a significant difference, it was analysed with Duncan’s multiple range test (DMRT) at the 5% level of significance.

Nitrogen fertilizer reduces the number of effective root nodules. Application of nitrogen resulted significantly increase the growth and yield attributes viz plant height, number of leaves, root shoot ratio, plant biomass, number of pods per plant and seed weight per plant. The optimum dose of nitrogen fertilizer to support soybean growth and yield was 95 kg ha^-1. Application of rhizobium can increase soybean yield. Application of rhizobium inoculation can increase the number of effective root nodules and seed weight per plant. Combined application of nitrogen and rhizobium can help in intensification of soybean cultivation in Indonesia.