title: In vitro nitrogen fixation, phosphate solubilization, survival and nutrient release by Azotobacter strains in an aquatic system.
abstract: In vitro nitrogen fixation, phosphate solubilization, survival and nutrient release by the three strains of Azotobacter (Mac-27, nitrogen fixer; PS-21, phosphate solubilizer and MSX-9, a phytohormone producer) in an aquatic system using three different organic substrates (cow-dung, piggery and poultry waste/excreta) were studied. It was shown that Azotobacter can grow and multiply in an aquatic system when fertilized either with cow-dung (100 mg 1(-1)), poultry (50 mg 1(-1)) or piggery (25 mg 1(-1)) waste/ excreta. Mac-27 and MSX-9 strains of Azotobacter fixed higher quantities of nitrogen (0.03-0.12 mg 1(-1) d(-1)) in aquaria water treated with cow-dung, while with poultry and piggery excreta, the three strains of Azotobacter fixed 0.03-0.09 mg 1(-1)d(-1) of nitrogen. O-PO4 concentration was also high in microbial-inoculated aquaria as compared to the controls which decreased with respect to time. Similarly, a decrease in total nitrogen concentration was also observed in the aquaria water after the maximum levels of fixation had been reached. Concomitant with the decrease in total nitrogen concentration, a simultaneous increase in NO3-N, NO2-N and NH4-N was observed. Maximum phytoplankton population was observed in MSX-9, while the population of zooplankton was maximum in Mac-27 inoculated aquaria. These studies indicated that Azotobacter can be used as a biofertilizer for enhancing nitrogen input and phosphate solubilization in fish ponds. Microbial inoculation along with organic substrate, however, has to be repeated at least at biweekly intervals.
authors.affiliation: Department of Zoology and Aquaculture, CCS Haryana Agricultural University, India. gargsk@hau.nic.in
authors.forename: S K
authors.initials: SK
authors.lastname: Garg
authors.forename: A
authors.initials: A
authors.lastname: Bhatnagar
authors.forename: A
authors.initials: A
authors.lastname: Kalla
authors.forename: N
authors.initials: N
authors.lastname: Narula
mesh_terms: D000818:Animals; D001395:Azotobacter / Q000378:metabolism*; D002470:Cell Survival / Q000502:physiology; D009566:Nitrates / Q000378:metabolism*; D009573:Nitrites / Q000378:metabolism*; D009586:Nitrogen Fixation / Q000502:physiology*; D009930:Organic Chemicals / Q000378:metabolism; D010710:Phosphates / Q000737:chemistry / Q000378:metabolism*; D010933:Plankton / Q000254:growth & development; D012995:Solubility; D014867:Water
chemical_list: D009566:Nitrates; D009573:Nitrites; D009930:Organic Chemicals; D010710:Phosphates; D014867:Water