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Soil Science Society of America Journal Abstract -

Residual Available Phosphorus in Near-Neutral and Alkaline Soils: II. Persistence and Quantitative Estimation1


This article in SSSAJ

  1. Vol. 46 No. 2, p. 335-338
    Received: June 25, 1981
    Accepted: Sept 14, 1981

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  1. P. E. Fixen and
  2. A. E. Ludwick2



A continuous cropping greenhouse study of 28 Colorado soils with phosphorus (P) rates of 0 and 30 ppm was conducted. The objectives were to (i) evaluate the persistence of residual available P in near-neutral and calcareous soils and (ii) to predict its quantity. Residual available P was defined as the amount of P removed fron soil by plant uptake until the NaHCO3-P level dropped to 10 ppm.

A residual effect of the fertilizer treatment persisted beyond six greenhouse crops for nearly one-half of the 28 soils. Recovery of applied fertilizer ranged from 47 to 119% and averaged 74%. The following equation was developed to predict the quantity of residual available P in soils: Residual P, mg/2 kg soil = −17.02 + 2.062 (NaHCO3-P, ppm) + 0.058 (NaHCO3-P × clay, %) − 0.187 (lime, % × clay). R2 = 0.90; 55 soil treatment combinations.

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