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Biogeosciences An interactive open-access journal of the European Geosciences Union
Biogeosciences, 14, 1153-1164, 2017
https://doi.org/10.5194/bg-14-1153-2017
© Author(s) 2017. This work is distributed under
the Creative Commons Attribution 3.0 License.
Research article
09 Mar 2017
Colloid-bound and dissolved phosphorus species in topsoil water extracts along a grassland transect from Cambisol to Stagnosol
Xiaoqian Jiang1, Roland Bol1, Barbara J. Cade-Menun2, Volker Nischwitz3, Sabine Willbold3, Sara L. Bauke4, Harry Vereecken1, Wulf Amelung1,4, and Erwin Klumpp1 1Institute of Bio- and Geosciences, Agrosphere Institute (IBG-3), Forschungszentrum Jülich GmbH, Jülich, Germany
2Swift Current Research and Development Centre, Agriculture and Agri-Food Canada, Box 1030, 1 Airport Rd., Swift Current, SK, S9H 3X2 Canada
3Central Institute for Engineering, Electronics and Analytics, Analytics (ZEA-3), Forschungszentrum Jülich GmbH, Jülich, Germany
4Institute of Crop Science and Resource Conservation, Soil Science and Soil Ecology, Nussallee 13, University of Bonn, 53115 Bonn, Germany
Abstract. Phosphorus (P) species in colloidal and dissolved soil fractions may have different distributions. To understand which P species are potentially involved, we obtained water extracts from the surface soils of a gradient from Cambisol, Stagnic Cambisol to Stagnosol from temperate grassland in Germany. These were filtered to  <  450 nm, and divided into three procedurally defined fractions: small-sized colloids (20–450 nm), nano-sized colloids (1–20 nm), and dissolved P (<  1 nm), using asymmetric flow field-flow fractionation (AF4), as well as filtration for solution 31P-nuclear magnetic resonance (NMR) spectroscopy. The total P of soil water extracts increased in the order Cambisol  <  Stagnic Cambisol  <  Stagnosol due to increasing contributions from the dissolved P fraction. Associations of C–Fe/Al–PO43−/pyrophosphate were absent in nano-sized (1–20 nm) colloids from the Cambisol but not in the Stagnosol. The 31P-NMR results indicated that this was accompanied by elevated portions of organic P in the order Cambisol  >  Stagnic Cambisol  >  Stagnosol. Across all soil types, elevated proportions of inositol hexakisphosphate (IHP) species (e.g., myo-, scyllo- and D-chiro-IHP) were associated with soil mineral particles (i.e., bulk soil and small-sized soil colloids), whereas other orthophosphate monoesters and phosphonates were found in the dissolved P fraction. We conclude that P species composition varies among colloidal and dissolved soil fractions after characterization using advanced techniques, i.e., AF4 and NMR. Furthermore, stagnic properties affect P speciation and availability by potentially releasing dissolved inorganic and ester-bound P forms as well as nano-sized organic matter–Fe/Al–P colloids.

Citation: Jiang, X., Bol, R., Cade-Menun, B. J., Nischwitz, V., Willbold, S., Bauke, S. L., Vereecken, H., Amelung, W., and Klumpp, E.: Colloid-bound and dissolved phosphorus species in topsoil water extracts along a grassland transect from Cambisol to Stagnosol, Biogeosciences, 14, 1153-1164, https://doi.org/10.5194/bg-14-1153-2017, 2017.
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It is the first study to distinguish the species of nano-sized (d=1−20 nm), small-sized (d=20−450 nm) colloidal P, and dissolved P (d<1 nm) of hydromorphic surface grassland soils from Cambisol, Stagnic Cambisol to Stagnosol using FFF and 31P-NMR. Evidence of nano-sized associations of OC–Fe(Al)–PO43/pyrophosphate in Stagnosol. Stagnic properties affect P speciation and availability by releasing dissolved inorganic and ester-bound P forms as well as nano-sized organic matter–Fe/Al–P colloids.
It is the first study to distinguish the species of nano-sized (d=1−20 nm), small-sized...
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