Response of soybean (Glycine max L.) to Bacillus strains and nitrogen fertilization

In soybean yield (Glycine max L.), N uptake during seed-filling period can be increased by Bacillus strains in association with Rhizobium. Three Bacillus strains (subtilis, megaterium and coagulance) were compared with Bradyrhizobium japonicum (BJ) effects on soybean. The experiment was conducted in Karaj Research Field during 2010. In urea placed at 20 cm below the soil surface before planting and Bacillus strains split-applied with seed before planting with 50 and 100 kg urea/ha as starter. The yield at 200 kg urea/ha (starter : 50 and 100 kg/ha) was 3740 kg/ha, but the mean yield of BJ applied treatments was 4114 kg/ha. (upto 10%). In BJ treatments at 50 kg urea/ha, N uptake was 347 kg/ha, but it was 12% greater than the mean of the 200 kg urea/ha treatments. Nitrogen uptake with combined BJ by B. subtilis (BS), B. megaterium (BM) and B. coagulance (BC) treatments was 434, 397 and 375 kg/ha at 50 kg urea/ha as starter, respectively. Yield maximization (12.5 to 16.5%) for BJ x Bacillus strains induced high nitrogen fixation when soybean plants acquired N from urea applied before planting.