Use of Radioactive 32p Technique to Study Phosphate Rock Dissolution in Acid Soils
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Date
2002
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Abstract
A laboratory experiment was conducted to evaluate the dissolution of six sources of phosphate rock in two acid soils (Ultisols): a sandy soil and a red clay soil. Labile P was determined using the radioactive 32P technique for Pi extractable P and resin extractable P. Incubations were conducted for 0, 1, 2, 3, 4 and 5 weeks for 32P exchangeable technique, 0 and 5 weeks for Pi technique and 5 weeks for resin technique. Rates of PR were 0 and 400 mgP/ha. The results showed that labile P in the sandy soil decreased from 0-1 weeks for all the PRs except Hahotoe PR and Hazara PR's. Between 1 and 5 weeks labile P remained relatively constant. The ranking of labile P from PRs was: North Carolina = Kouribga > Matam > Hahotoe = Hazara> Patos de Minas. In the red soil, labile P from all PRs appeared to be relatively unchanged during the 0-5 week incubation. Pi extractable P in sandy soil showed no significant differences due to incubation time. In the red clay soil, there was a significant decrease in Pi-P extracted from soil mixtures with PRs after 5 weeks as compared to 0 weeks. Results of the Resin-extractable P in both sandy and red soils were in agreement with labile P as measured by 32P exchange technique.
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Acid soils
Citation
Mahisarakul, J., G.L. Mullins and S.H. Chien. 2002. “Use of Radioactive 32P Technique to Study Phosphate Rock Dissolution in Acid,” Assessment of Soil Phosphorus Status and Management of Phosphatic Fertilisers to Optimise Crop Production, IAEA-TECDOC- 1272, pp. 256-264, International Atomic Energy Agency, February