Factors related to the occurrence of phosphate solubilizing bacteria and their isolation in vertisols

Abstract

The aim of present research is to isolate phosphate solubilizing bacteria and study their relationship with physical, chemical and biological properties of the soil. Phosphate Solubilizing Bacteria (PSB) were enumerated in 66 soil samples collected from eleven districts of Northern Karnataka. It revealed the presence of PSB in 31 soil samples and indicated a strong positive correlation to exist between total bacterial populations and the population of PSB. The organic carbon and available N content of soils also showed a significant positive conelation while soil pH, available P and total P showed a positive but non-significant correlation with that of PSB population. Thirty one PSB containing soil samples were grouped based on their similarity in bacterial population composition using cluster procedure of SAS and population of total and phosphate solubilizing bacteria as similarity measures. Five soil classes were created and subjected to ANOVA to find any significant effect of soil characteristics. Cation exchange capacity, exchangeable Ca (both in cmol kg -1) and clay content showed significant differences between different soil unsupervised formed groups. A total of 55 PSB were isolated from the rhizosphere soil samples collected from different crops grown in vertisols of Northern Karnataka. These isolated PSB strains will be identified and efficient strains will be selected and used for further studies. © 2007 Academic Journals.