Agronomic Efficiency of Indian Rock Phosphates in Acidic Soils Employing Radiotracer A-Value Technique
2007
Shrivastava, M. | Bhujbal, B.M. | D'Souza, S.F.
A greenhouse pot culture study was conducted to evaluate the agronomic efficiency of two rock phosphates from Mussoorie (MRP) and Purulia (PRP) in two acidic soils from Dapoli (Maharashtra) and Aruvanthklu (Karnataka), India, by growing maize (cv. Ganga) as the test crop and using 32phosphorus (P) single superphosphate (32P = SSP) as a tracer (A-value technique). Dry-matter yield and P uptake increased significantly with the application of P fertilizers compared to control treatment (without P) in both the soils. There was no significant difference with respect to dry-matter yield among the P fertilizer treatments. However, P uptake by the shoots was found to be significantly higher in the PRP treatment in only Dapoli soil compared to other P fertilizer treatments. Phosphorus derived from fertilizer decreased in rock phosphate treatments compared to standard 32P-SSP treatment in both the soils, indicating an excess availability of P from the rock phosphates. A-values of soil and rock phosphate indicate a relatively higher P availability from Aruvanthklu soil compared to Dapoli soil; A-values for the rock phosphates were in the order PRP > MRP. The substitution ratio showed that the availability of P from both the rock phosphates were less than SSP in both the soils.
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