Potential for Eppawala Apatite as directly applied low-cost fertilizer for rice production in Sri Lanka
1995
Dahanayake, K. | Ratnayake, M.P.K. | Sunil, P.A.
Apatite in Sri Lanka is mined from Eppawala (Eppawala Rock Phosphate or ERP). The finely ground product is used as a direct application fertilizer for tea, rubber and coconut. ERP is an indiscriminate mixture of more soluble primary crystals and a less soluble secondary phosphate matrix rich in ferruginous and aluminous compounds with an average P2O5 content of 30%. The primary crystals can easily be separated from the groundmass by mechanical separation to produce selectively mined primary crystals (SERP) which has higher P2O5 (35 to 42%) and lower R2O3 contents (around 1%) than the matrix. The ground SERP shows promise, as measured using yield and bicarbonate-extractable soil P, as fertilizer for rice grown in lowland and midland acid soils. In the second crop residues of SERP produced larger yields and bicarbonate-extractable P than Triple super phosphate (TSP) for the first crop. TSP is imported and its price is four times that of SERP. Therefore SERP is a potentially more profitable alternative fertilizer for TSP for rice on Sri Lankan acid soils.
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