Abstract :
The study was conducted in the greenhouse and in the field on the Ultisol of East Lampung Province during the rainy season of 2011. The objective was to obtain an effective isolate of phosphate solubilizing bacteria that able to improve the productivity of soybean in acid soil. In the greenhouse, treatments were arranged in a split plot design with three replications. The main plot was the equivalent dose of lime: 0, 400, and 800 kg dolomite / ha. Subplots consisted of factor I which was P fertilizer equivalent to 0, 100, and 200 kg SP36/ ha, and factor II inoculation of phosphate-solubilizing bacteria (Pseudomonas sp), namely without inoculation, isolate P1, isolate P2 and isolate P3. The field experiment used split plot design with three replications. The main plots were the SP36 doses: 0, 100 and 200 kg SP36/ha. The subplots were phosphate solubilizing inoculation: without inoculation, isolate P1, isolate P2, isolate P1 + P2 and a commercial inoculant. Results of the greenhouse showed that isolates P2 increased grain yield by 19% and when combined with 800 kg dolomite/ha increase yield by 42% compared to control (without fertilizer P and P-solubilizing). Whereas P1 isolate was effective in dose of 400 kg/ha dolomite, with a yield improvement of 26%, followed by P2 (21%) and P3 (17%). Without P fertilizer, P2 isolate was able to increase yield by 23% equivalent to grain yield obtained from 200 kg SP36/ha. The highest yield increase (50%) was obtained by the treatment of P2 isolates + 200 kg SP36/ha. On the field experiment at fertilization rate of 100 kg SP36/ha, P2 isolate was able to increase yield by 48.7% followed by the commercial inoculant of 33%, isolates of P1+P2 of 20% and P1 isolate of 16% over the control treatment. Fertilizer alone at a dose of 100 kg SP36/ha did not improve yield, whereas yield increased at dose of 200 kg SP36/ha was 24.8%.
