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This article in JEQ

  1. Vol. 33 No. 1, p. 99-106
     
    Received: Feb 12, 2003
    Published: Jan, 2004


    * Corresponding author(s): Katarina.Borling@mv.slu.se
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doi:10.2134/jeq2004.9900

Soil Variables for Predicting Potential Phosphorus Release in Swedish Noncalcareous Soils

  1. Katarina Börling *a,
  2. Erasmus Otabbonga and
  3. Elisabetta Barberisb
  1. a Department of Soil Sciences, Swedish University of Agricultural Sciences, P.O. Box 7014, SE-750 07 Uppsala, Sweden
    b Dipartimento di Valorizzazione e Protezione delle Risorse Agroforestali, University of Turin, Via Leonardo da Vinci 44, I-10095 Grugliasco (TO), Italy

Abstract

The accumulation of P in agricultural soils due to fertilization has increased the risk of P losses from agricultural fields to surface waters. In risk assessment systems for P losses, both P release from soil to solution and transport mechanisms need to be considered. In this study, the overall objective was to identify soil variables for prediction of potential P release from soil to solution. Soils from nine sites of the Swedish long-term fertility experiment were used, each with four soil P levels. Phosphorus extractable with CaCl2 was used as an estimate of potential P release from soil to solution. Ammonium lactate–extractable phosphorus (P-AL) or NaHCO3–extractable phosphorus (Olsen P) could not be used alone for prediction of potential P release since soils with high phosphorus sorption capacity (PSC) released less P than soils with low PSC at the same soil test phosphorus (STP) level. Degree of phosphorus saturation (DPS) was calculated as Olsen P or P-AL as a percentage of PSC derived from P sorption isotherms or from Fe and Al extractable in ammonium oxalate. The CaCl2–extractable total phosphorus (CaCl2–TP) was exponentially related to these DPS values (r 2 ≥ 0.79). The CaCl2–TP was also linearly related to ratios between Olsen P or P-AL and a single-point phosphorus sorption index (PSI; r 2 ≥ 0.86). These ratios, which are easily determined and gave good correlations with CaCl2–TP, seemed to be the most useful estimates of potential P release for risk assessment systems.

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Copyright © 2004. American Society of Agronomy, Crop Science Society of America, Soil Science SocietyASA, CSSA, SSSA