title: Retention of phytosiderophores by the soil solid phase - adsorption and desorption.
abstract: OBJECTIVE
  Graminaceous plants exude phytosiderophores (PS) for acquiring Fe. Adsorption of PS and its metal complexes to the soil solid phase reduces the FePS solution concentration and hence Fe uptake. In this study we aimed to quantify adsorption, and to determine to what extent adsorption depends on the complexed metal and on soil properties. Furthermore, we examined if adsorption is a reversible process.
  
  
  METHODS
  Adsorption and desorption of PS and metal-PS complexes were examined in batch experiments in which the PS 2'-deoxymugineic acid (DMA) and its metal-complexes (FeDMA, CuDMA, NiDMA and ZnDMA) interacted with several calcareous soils.
  
  
  RESULTS
  Adsorption of DMA ligand (0-1000 μM) and metal-DMA complexes (0-100 μM) was linear in the concentration range examined. Adsorption varied by a factor ≈2 depending on the complexed metal and by up to a factor 3.5 depending on the soil. Under field-like conditions (50 % water holding capacity), 50-84 % of the DMA was predicted to be retained to the soil solid phase. Alike adsorption, desorption of metal-DMA complexes is fast (approximate equilibrium within 1 hour). However, only a small fraction of the adsorbed FeDMA (28-35 %) could be desorbed.
  
  
  CONCLUSIONS
  Despite this small fraction, the desorbed FeDMA still exceeded the amount in solution, indicating that desorption of FeDMA from soil reactive compounds can be an important process buffering the solution concentration.
authors.affiliation: Department of Environmental Geosciences and Research Network Environmental Science, University of Vienna, Althanstraße 14 (UZA II), 1090 Vienna, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Walter
authors.affiliation: Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences, Konrad Lorenz Strasse 24, 3430 Tulln, Austria.
authors.forename: E
authors.initials: E
authors.lastname: Oburger
authors.affiliation: Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria.
authors.forename: Y
authors.initials: Y
authors.lastname: Schindlegger
authors.affiliation: Department of Chemistry, University of Natural Resources and Life Sciences, Muthgasse 18, 1190 Vienna, Austria.
authors.forename: S
authors.initials: S
authors.lastname: Hann
authors.affiliation: Department of Forest and Soil Sciences, University of Natural Resources and Life Sciences, Konrad Lorenz Strasse 24, 3430 Tulln, Austria.
authors.forename: M
authors.initials: M
authors.lastname: Puschenreiter
authors.affiliation: Department of Environmental Geosciences and Research Network Environmental Science, University of Vienna, Althanstraße 14 (UZA II), 1090 Vienna, Austria.
authors.forename: S M
authors.initials: SM
authors.lastname: Kraemer
authors.affiliation: Department of Environmental Geosciences and Research Network Environmental Science, University of Vienna, Althanstraße 14 (UZA II), 1090 Vienna, Austria.
authors.forename: W D C
authors.initials: WD
authors.lastname: Schenkeveld
keywords: Adsorption; Deoxymugineic acid; Desorption; Fe acquisition; Phytosiderophore; Rhizosphere