Phosphorus and Aluminum Interactions in the Acidification of Soils1
- P. F. Pratt2
Two soils containing relatively large amounts of basic Ca phosphates were acidified from neutrality to pH 3.5. Acidification produced high P solubility and because of this the A1 solubility remained < 1.0 ppm. for one soil and < 0.5 ppm. for the soil that had the greatest P solubility. Maximum P solubility was obtained at pH 4.2 with both soils. The high P solubility did not prevent accumulation of exchangeable A1 when the pH of the soil decreased to pH 3.5. During acidification the Ca phosphate fraction decreased about 50% in one soil and about 80% in the other. This decrease was largely balanced by an increase in NH4F-extractable P or A1 phosphates. Acidification of these types of soils to pH values as low as 4.7 should produce little if any A1 toxicity.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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