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) greater than or equal to 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) greater than or equal to 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

Published in

Journal of Environmental Quality
2004, Volume: 33, number: 1, pages: 99-106
Publisher: AMER SOC AGRONOMY

SLU Authors

• Börling, Katarina

  • Department of Soil Sciences, Swedish University of Agricultural Sciences
    

• Otabbong, Erasmus

  • Department of Soil Sciences, Swedish University of Agricultural Sciences
    

UKÄ Subject classification

Agricultural Science


Permanent link to this page (URI)

https://res.slu.se/id/publ/5153