Division of Soil Science and Agricultural Chemistry, Indian Agricultural Research Institute, New Delhi, 110012
Present address: 1National Research Centre for Onion and Garlic, District Pune, Rajgurunagar, Maharashtra, 410505
A pot experiment was conducted to know the direct and residual effect of rock phosphate when applied along with phosphate solublizers and farmyard manure on available phosphorus, organic carbon and the viable counts of phosphate solubilizers in soil. The soil after harvest of soybean crop at 60 days stage was analyzed to know the direct effect while, soils after the harvest of mustard and followed by wheat were analyzed for studying the residual effect. After soybean the 0.5 M NaHCO3 extractable P due to triple superphosphate was found to be the highest (19.0 mg P kg−1 soil) followed by North Carolina, Udaipur and Mussoorie rock phosphates with 14.1, 12.0 and 11.7 mg P kg−1 soil, respectively. Amongst the phosphate solublizers, Aspergillus awamori showed significant effect in improving available P, which was followed by Pseudomonas striata. Combined application of phosphate solublizers in presence of FYM improved the organic carbon status and proliferation of phosphate solublizers. After mustard the available P in soil was highest in TSP treatment but decreased after wheat crop. Though, a difference was recorded amongst rock phosphates on soil available P after mustard, it was not noticed after wheat. Seed treatment with Aspergillus awamori in mustard and wheat improved the soil P status over Bacillus polymyxa. The number of viable counts of phosphate solubilizers in the rhizosphere soil after the harvest of both the crops due to P sources and seed inoculation with phosphate solubilizers were improved over control. This could be due to the improvement in the levels of organic carbon.
Rock phosphates, phosphate solubilizers, available phosphorus, Aspergillus awamori, Pseudanomas striata, Bacillus polymyxa, organic carbon, viable counts, soybean, mustard, wheat
