Solubility of Phosphorus in Chemical Extractants as Indexes to Available Phosphorus in Ohio Soils

Thompson, L. F.; Pratt, P. F.

Solubility of Phosphorus in Chemical Extractants as Indexes to Available Phosphorus in Ohio Soils

1954

Thompson, L. F. | Pratt, P. F.

Eighteen samples of soils were subjected to greenhouse cropping with alfalfa and corn and to various extractant solutions for measurements of soluble P. The P removed from the soils by alfalfa and the “A” values calculated from the uptake by corn of radioactivity tagged superphosphate were used as a measure of plant-available P. The accuracy of estimation of available P by the solubility data was obtained by comparing the P solubility in the various extractant solutions against the plant-available P. The Bray No. 1 solution (0.03 N NH₄F-0.025 N HCl) and the 0.5 M NaHCO₃ solution extracted amounts of P that were accurate estimates of plant-available P. The Bray No. 2 solution (0.03 N NH₄F-0.1 N HCl), 0.002 N H₂SO₄, and citric acid extracted amounts of P that when plotted against the plant data gave a distinctly different relationship for young soils formed from high-lime late Wisconsin till than for older soils formed from more acid parent materials.

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