Rhizobacterial isolate from Merapi vulcanic ash is an osmotolerant (>2.75 M NaCl) bacteria. Phosphate solvent and Nitrification-Ammonification characteristics are strong, which make it potential to be developed into natural fertilizer inoculum. Its population dynamics study on rice rhizosphere under drought stress showed long lag phase (3 weeks) and only entered exponential phase after until 6th weeks, although there were apparent correlations between inoculum and drought stress to root and shoot growth. Research's goal is to determine the best application method from various osmotolerant Rhizobacteria Merapi's liquid inoculum formulas on rice plant in drought stress in order for it to be able to give faster response dan increase both growth and rice harvest. Research's results showed that Rhizobacterial population grew faster on soil extract formula which was applied to seeds rather than to seedlings and shortened lag phase (2 weeks). Various liquid formula and their application method correlate each other on rice plant height under drought stress, but the coconut water 50%+ soybean water 50% formula which was applied to seeds resulted better results on dry mass and seeds number, as compared to application on seedlings.