Use of Isotopic Dilution in a Study of Inorganic Phosphorus Fractions from Different Soils1
- Andrew D. Dunbar and
- Dale E. Baker2
The study consisted of a factorial experiment in which each of seven widely different soils was treated with 0 and 1 lime requirements and 0, 500, and 1,000 ppm of P. Prior to fractionating the soil P, a constant amount of P32 was added to each sample. The results indicate that for these acid soils, P was extracted predominantly with the aluminum phosphate and iron phosphate fractions. Results for isotopic dilution indicated that the different P fractions ranked in the following order with respect to amounts of active solid phase P removed per unit of solid phase P: water soluble P > aluminum phosphate > iron phosphate > calcium phosphate. The rapidity with which P32 reached an equilibrium with P extracted from soils with NH4F (aluminum phosphate) indicates why fluoride-extractable P has correlated highly with availability of soil P.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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