A greenhouse experiment was conducted to evaluate the productivity, chemical composition and the abundance of cyanobacteria in the soil based cyanobacteria inoculum (SE31) commonly used as biofertilizer in rice cultivation Four local cyanobacteria strains namely, Anabaena oryzae, Nostoc calcicoia, Microchaete tenera and Cyirndrosperrnum muscicoia were used each separately in addition to the control treatment (soil only without cyanobacteria inoculation) in the production of 881 inoculum. Results showed a large variability of biomass production of 881 depending on the incubation period. The indigenous cyanobacteria (control) gave its highest SBl biomass of i104 g m'F‘E atter one week then tended to decrease with increasing incubation time Up to 4 weeks. Nitrogen percentages of the produced 881 ranged from 0.56 (control) to 2.00 (C. muscicoia). Phosphorus Percentages ranged from 0.16 (Aoryzae) to 0.30 (, Mienera or C.rnuscicola). Carbon percentage ranged from 1.33 (control) to 18? (N. calcicola). The highest GIN ratio {8.86) noticed with A. oryzae after 4 weeks incubation period, while the lowest one (2.25) was for Cmuscicoia after 3 weeks incubation. The highest mean NIP ratio of 9 T2 was for Cmuscicoia against the lowest one (4.18) for Aoryzae. The cyanobacteria count decreased with Increasing the incubation up to 4 weeks.