Effect of organic and inorganic fertilizer applications on phosphate solubilizing bacteria in the rhizosphere of maize (Zea mays L.)

A field experiment was conducted between August and October, 2014 at the Department of Microbiology to assess the effect of organic and inorganic fertilizers on the population and activities of Phosphate Solubilizing Bacteria (PSB) in the rhizosphere of maize variety BR9928DMRSR-Y. Three treatment groups were used in the study and these were: Groups which received applications of organic fertilizer (Poultry litter) alone, groups which received applications of inorganic fertilizer (NPK) and the third group which was the control (CON) did not receive any fertilizer application. A total of twenty-three bacteria were isolated and in-vitro screening was done for different phosphate solubilization activity. The study revealed that maximum population of total heterotrophic bacteria (26.8×109 CFU/g) was obtained with organic fertilizer (OM) treatment. Among the different PSB isolates, OMPSB had the highest bacterial count of 10.2×109. The lowest bacterial populations were obtained from IFPSB with 6.0×109 CFU/g. Out of the 23 PSB isolates, 18 were positive for phosphate solubilization with OMPSB8 showing the highest zone with 16 mm. Results showed that application of organic fertilizers enhanced the bacterial population and also showed increase in phosphate solubilization activities in rhizosphere soil compared to NPK and control treatments. This shows that organic fertilizers would be able to sustain the soil fertility for a longer period by meeting the demand of present and future generations.