Shelf life and colonization of soil by clay based cyanobacterial inocula

Four heterocystous cyanobacteria, isolated from grasslands of Ujjain were selected to prepare the clay based inoculants. Inoculants were evaluated for shelf life in terms of the titer value at 6 month intervals for 24 months. For colonization by inoculants in natural grasslands, the clay based inocula were applied to the field at: 40, 80 and 120 kg/ha and their survival was estimated at different time interval. Fuller's earth based inoculants had showed 50-65% survival after two year storage. After showing an initial decline, the population of the inoculated cyanobacteria became stable after 3 months. The inoculated strains persisted in the soil for longer duration, even after four months, their population was about 10-70 times higher than that of the uninoculated plots.