Abstract:
Efficiency of P chemical fertilizers absorption in peat lands can be increased by using phosphate - solubilizing bacteria (PSB). Phosphate solubilizing bacteria is one of soil microorganism group which is capable of dissolving the source of P that accumulates in the soil and turn it into an available form for plants. Because of its role, the PSB can be employed as biofertilizer agent. The objective of this study was to analysis shelf life of PSB in liquid biofertilizer amended with additive substances such as starch and tween + glycerol. Four potential PSB isolates were subcultured on Pikovskaya's slant agar. The isolates were cultivated on Pikovskaya's broth separately and then mixed them equally with a combination of two, three and four isolates resulting starter 1 (consist of BB_UB6, BB_K2, BB_K9 and BB_HS13), starter 2 (consist of BB_UB6, BB_K2 and BB_K9) and starter 3 (consist of BB_UB6 and BB_K9). The fermentation media were inoculated by those starters and also added with starch and tween + glycerol separately, then incubated for 4 days at room temperature to produce liquid biofertilizer. Biofertilizer were pack afterward and stored for 0, 30, 90 and 180 days in refrigerator. Each shelf life was analyzed by calculating the population of PSB and pH measurement. The addition of additive substances are generally able to maintain and even improve the stability of PSB populations in liquid biofertilizer until 180 days storage and bacterial cell number are still in the range of quality standards (1010 - 1011 CFU/ml). Liquid biofertilizer amended with additive substances still has good pH range for acidophilic PSB growth (4,1 - 5,6) until 180 days storage.
