The establishment of inoculants, viz. Azospirillum sp. and Pseudomonas striata or Glomus fasciculatum in the rhizosphere of cotton was studied in the presence or absence of biogas spent slurry (BSS) at different N and P levels. In general, addition of BSS was found to stimulate the establishment of all inoculated organisms in the rhizosphere. The population of Azospirillum and P-solubilizers were highest in the treatment receiving combined inoculation of Azospirillum sp. and P. striata along with 50% of recommended N and 100% of recommended P as rock phosphate where as micorrhizal spore numbers in soil and per cent root colonization were highest in plants inoculated together with Glomus fasciculatum and Azospirillum sp. in the absence of N and P fertilizers. Plant dry biomass, N and P uptake and seed cotton yield were highest in the treatment receiving dual inoculation of Azospirillum sp. and P. striata along with application of 50% N and 100% P as rock phosphate