Effect of common ions on phosphorus sorption and lability in Greek alfisols with different pH

Sabry M. Shaheen, Christos D. Tsadilas, Kent M. Eskridge

Research output: Contribution to journalArticlepeer-review

24 Scopus citations


Phosphorus (P) mobility in soils is controlled by its interaction with the soil matrix, nutrients, and amendments. The aim of this study was to test the hypothesis that soils with different pH differ in their ability to bind P as influenced by the presence of the common cations and anions that are added to soil with fertilizers. Therefore, this study was conducted to investigate the effect of common fertilizer ions on phosphorus sorption and lability characteristics in three soils differing in their pH. Phosphorus sorption isotherms were assessed on an acid, neutral, and alkaline alfisol in background solutions containing one of the ions K, NH4, Ca2, NO3, HCO3, or SO4. The Freundlich equation was adjusted to describe the sorption. In addition, distribution coefficients values were obtained for soil and background electrolyte. Lability of the sorbed P was evaluated by NaHCO3 extraction after its sorption.The Freundlich equation fitted closely to the sorption data. Alkaline soil exhibited greater P sorption than the acid and neutral soils. Both K and NH4 equally decreased P sorption as opposed to Ca, with more P in the labile form in all the soils studied. Phosphorus sorption was enhanced by HCO3 compared with SO4 and NO3 at all pH levels. Both NO and SO4 increased the labile P compared with HCO3. Sulfate addition, however, resulted in more P in the labile pool compared with NO3 in acid and neutral soils, whereas NO3 addition resulted in the highest amount of the labile P form in the alkaline soil. These results have important implications on P management in relation to other nutrients.

Original languageEnglish (US)
Pages (from-to)21-26
Number of pages6
JournalSoil Science
Issue number1
StatePublished - Jan 2009


  • Alfisol
  • Background electrolyte
  • Lability
  • Phosphorus adsorption
  • Soil pH

ASJC Scopus subject areas

  • Soil Science


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