Fertilizer value of indigenous phosphate rock modified by mixing with pyrite and composting with paddy straw

Four indigenous phosphate rocks (PR) from Mussourie, Udaipur, Purulia and Jhabua modified by mixing either with iron pyrite or composting with paddy straw alongwith or without PSM inoculation (Phospho-compost) increased water soluble and citrate soluble P content of the original rocks. A phosphate-deficient acid soil incubated with either of the modified products for 105 days increased the available (Olsen's) P content of soil after 60 days of incubation and the increase was more due to application of phospho-compost than PR + pyrite mixture. Results of pot culture study with rice as test crop revealed that application of modified PRs significantly increased dry matter yield and P uptake by the crop. Of the different PRs used, MPR and JPR proved to be better for utilization upon modification