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Research article - Peer-reviewed, 2015

Phosphorus speciation of clay fractions from long-term fertility experiments in Sweden

Eriksson, Ann Kristin; Gustafsson, Jon-Petter; Hesterberg, Dean


Phosphorus (P) losses from agricultural soils constitute a main driver for eutrophication of the Baltic Sea. There is limited knowledge about sorption and release processes of P in these soils, especially concerning the effects of fertilization. In this study, P speciation of the clay fractions from six different soils in long-term fertility experiments in Sweden was investigated by P K-edge XANES spectroscopy. As expected, unfertilized soils had lower concentrations of acid-digestible P compared with fertilized soils. Based on best-fit standards that emerged from linear combination fitting (LCF) of XANES spectra, phosphate sorbed on iron (Fe) (hydr)oxides was a dominant P species in clay fractions from unfertilized soils containing more than 35 mmol kg(-1) of oxalate-extractable Fe. In contrast, P sorbed on aluminum (Al) (hydr)oxides predominated in soils with lower concentrations of oxalate-extractable Fe. A greater proportion of organically bound P was fit for soil samples containing >2% organic carbon. The soils included one calcareous soil for which a greater proportion of P was fit as apatite. After long-term fertilization, P had accumulated mainly as P adsorbed to Al (hydr) oxides according to the XANES analysis. Our research shows that P speciation in fertilized agricultural soils depended on the level of P buildup and on the soil properties. (C) 2014 Elsevier B.V. All rights reserved.


Soils; X-ray absorption spectroscopy; Sweden; Phosphorus; Phosphate; Clays

Published in

2015, volume: 241, pages: 68-74

Authors' information

Eriksson, Ann Kristin
Swedish University of Agricultural Sciences, Department of Soil and Environment
Swedish University of Agricultural Sciences, Department of Soil and Environment
Hesterberg, Dean
North Carolina State University (NC State)

UKÄ Subject classification

Soil Science

Publication Identifiers


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