Abstract
Several studies have shown that the effectiveness of phosphate rock (PR) as phosphorus source for direct application is largely determined by the extent of its dissolution in moist soil. An incubation experiment was carried out in the Soil Science laboratory of Obafemi Awolowo University to monitor the rate of P release from thermally altered Ogun phosphate rocks (OPR) and mineral P fertilizers (SSP). Four sources of phosphorus (P) were used: OPR with Na2CO3 in ratio 2:1 at 900 0C (TOPR); OPR without Na2CO3 at 900 0C (UOPR); OPR alone at ordinary temperature (NOPR) and single superphosphate (SSP); three rates of each phosphate rock source (0, 30, and 60 Kg ha-1) were used on soil samples with varying pH values. Soil pH and available P were determined in all the treated samples every fortnight for six weeks. There was no significant difference at p ≤ 0.05 in the available P and the pH values among all the treatments. Soil samples treated with SSP had the highest value for available P at 2nd week of incubation while samples treated with TOPR had the highest P values at 4th and 6th week of incubation in all the treated samples. Hence, thermal treatment of the mixture of phosphate rock and Na2CO3 in 2:1 ratio at 900 0C enhances rate of P release irrespective of soil pH value.
Keywords:
availability
phosphorus
thermally
phosphate
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