Solubilization of Rock Phosphate by Spent Wash Solubilization of Phosphorus from Low-Grade Udaipur Rajasthan Rock Phosphate Using Spent Wash from Faizabad Utter Pradesh

High-grade rock phosphate (P2O5>30%) is essential for manufacturing P fertilizers. only 39% is of high grade which could meet hardly 35-40% of the demand of P fertilizers (Indian Bureau of Mines 2014). In India, there is a predominance of low grade rock phosphate reserves and out of 260 million ton only 15.3 million ton is of high grade quality. The consumption of apatite and rock phosphate in 2011-12 was about 3.96 million tonne. Rock phosphate is usually inert in alkaline and calcareous soils. While exploring the options available for increasing the solubility of low grade RP, it was thought that the spent wash which is highly acidic (pH: 3.5-4.5) and generated as a waste in huge quantities (6.8xl010 litres/year) in the country, may be utilized for this purpose. Spent wash has considerable manurial potential. The extent of P-solubilization from low-grade Udaipur rock phosphate (RP) by spent wash (SW) was studied by mixing RP and SP in different ratios i.e. 1:1, 1:2, 1:5, 1:10, 1:20, 1:40, 1:60, 1:80 and 1:100. The amount of phosphorus solubilized, increased with increasing rate up to RP: SW::1: 20 and thereafter, smaller increase solubilized phosphorus.