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ThesisItem Open Access Role of organic acids produced during decomposition of rice straw in the solubilization of rock phosphate(CCSHAU, 2005) Anju Kumari; Kapoor, K.K.Production of organic acids by phosphate solubilizing microorganisms is the most important mechanism of P solubilization. There is solubilization of P from insoluble P sources such as rock phosphate during decomposition of lignocellulosic wastes. The identification of organic acids produced during decomposition of rice straw was attempted in the present studies. Changes during decomposition of rice straw amended with tricalcium phosphate (TCP) and Udaipur rock phosphate (URP) were studied in laboratory incubation experiment. Initially C: N ratio was adjusted to 40:1. The organic C content of rice straw was found to decrease and total N increased with time, with the effect C: N ratio of rice straw decreased as the decomposition progressed. At 15 days, the pH decreased to acidic range in all the treatments, which again increased to alkaline range at 30 and 60 days. Water-soluble P and Citric acid soluble P increased at 15 days incubation and decreased at 30 and 60 days decomposition period. The amount of citric acid soluble P was higher in treatments containing TCP or URP. Citric, oxalic, formic and maleic acid were detected during decomposition of rice straw. Citric acid and oxalic acids were produced almost in all the treatments and the maximum amount of organic acids were detected at 15 days. The concentration decreased to negligible amount at 30 and 60 days. Citric acid and oxalic acids were the major acids produced which are responsible for P solubilization from TCP and URP. Citric acid was found to be most effective in solubilization of TCP and URP. The P solubilization with sulphuric acid was lower as compared to organic acids.