Relationship between Soluble and Extractable Phosphorus in Some Calcareous Soils of Iran
- Seifollah Amin Sichani *,
- Shahrokh Zand Parsa and
- D.W. Nelson
The relationship between water-extractable P (soluble P) and NaHCO3-extractable P was determined in different water/soil ratios. The values of 0, 45, 90, and 180 mg kg−1 soil as KH2PO4 were added to seven calcareous soil series from southern Iran (for two soil series additional P rates of 360, 720, and 1080 mg P kg−1 soil as KH2PO4 also was employed). Soluble P in water/soil ratios of 10:1, 25:1, 100:1, and 500:1 was measured by Murphy and Riley method (1962) after 2 h shaking. Sodium bicarbonate—extractable P also was determined in all soils. The results indicate that there was a linear relationship between the logarithm of soluble and NaHCO3-extractable P when NaHCO3-extractable P was less than 150 mg P kg−1 soil. There also was a linear relationship between soluble P and the water/soil ratio up to 100:1 for these soils. The amount of P released per unit soil weight at water/soil ratios greater than 100:1 was approximately constant.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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