Biology and Fertility of Soils

, Volume 31, Issue 6, pp 525–532

Effect of maize root mucilage on phosphate adsorption and exchangeability on a synthetic ferrihydrite

  • Alain Gaume
  • P.G. Weidler
  • E. Frossard
ORIGINAL PAPER

DOI: 10.1007/s003740000206

Cite this article as:
Gaume, A., Weidler, P. & Frossard, E. Biol Fertil Soils (2000) 31: 525. doi:10.1007/s003740000206

Abstract

 This study was conducted to determine the influence of root mucilage (RM) from Zea mays, polygalacturonic acid (PGA), and galacturonic acid (GA), on the adsorption, desorption, and exchangeability of orthophosphate (P) on a synthetic ferrihydrite in deionized water. The adsorption rate and affinity on the oxide decreased in the order P>GA>PGA≥RM. The results suggest that P and GA were adsorbed by ligand exchange on Fe-OH surface sites, while RM and PGA might in addition also be adsorbed by hydrogen and van der Waals bonds to the oxide surface. Whereas P and GA could be adsorbed at sites located inside the micropores of ferrihydrite aggregates, PGA and RM probably remained on the external surfaces because of their large molecular weight. The preliminary adsorption of organic compounds decreased the subsequent P adsorption. The larger decrease of P adsorption occurred when dry ferrihydrite powder was directly added to the RM/water suspension. This effect was due to the flocculation of ferrihydrite aggregates, which limited the transport of P to the adsorption sites. Preliminary adsorption of GA also decreased P adsorption, because both compounds competed for the same Fe-OH sites. The ability of the organic compounds to desorb P from the ferrihydrite was not very pronounced and decreased in the order GA>PGA≥RM. The preliminary adsorption of organic compounds on the oxide resulted in an increase in isotopically exchangeable P in 300 min compared to the treatment without organic compounds. However, because of its higher affinity for the oxide surface, P exchangeability was not modified when P was added before the organic compounds.

Key words FerrihydritePhosphatePolygalacturonic acidRoot mucilageZea mays

Copyright information

© Springer-Verlag Berlin Heidelberg 2000

Authors and Affiliations

  • Alain Gaume
    • 1
  • P.G. Weidler
    • 2
  • E. Frossard
    • 1
  1. 1.Institute of Plant Sciences, Swiss Federal Institute of Technology (ETH Zurich), Eschikon 33, Postfach 185, 8315 Lindau, Switzerland e-mail: emmanuel.frossard@ipw.agrl.ethz.ch Tel.: +41-52-3549140 Fax: +41-52-3549119CH
  2. 2.Institute of Terrestrial Ecology, Swiss Federal Institute of Technology (ETH Zurich), Grabenstrasse 3, 8952 Schlieren, SwitzerlandCH