Phosphorus Intensity, Quantity, and Capacity Factors of Representative Alfisols of Greece
1983
Keramidas, V. Z. | Polyzopoulos, N. A.
A number of phosphorus intensity indices, including P concentration, activity of the H₂PO₄ ion, and certain chemical potentials, were found to satisfactorily predict P uptake by ryegrass from 14 representative Alfisols of northern Greece, both initially and also upon prolonged cropping. Simple intensity indices, such as P concentration in either CaCl₂ or H₂O extracts, proved as good as more elaborate ones. Activity of phosphate on the solid phase correlated most closely when expressed as a molar fraction. The two common P quantity indices, E-value and Resin-P, also proved satisfactory predictors. Bray 1, Olsen, and Colwell tests were equally effective to more complicated and tedious indices. Phosphorus capacity indices were generally found ineffective as predictors, though “ultimate” P capacities as determined from cumulative P uptake were similar for all soils studied.
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