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Soil Science Society of America Journal Abstract - Soil Fertility & Plant Nutrition

Phosphate Release Kinetics in Calcareous Grassland and Forest Soils in Response to H+ Addition

 

This article in SSSAJ

  1. Vol. 77 No. 6, p. 2060-2070
     
    Received: Feb 22, 2013
    Published: November 1, 2013


    * Corresponding author(s): Yvonne.oelmann@uni-tuebingen.de
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doi:10.2136/sssaj2013.02.0072
  1. Fabian Alta,
  2. Yvonne Oelmann *a,
  3. Ingo Schöningb and
  4. Wolfgang Wilckec
  1. a University of Tübingen Geoecology Rümelinstrasse 19-23 72070 Tübingen Germany
    b Max-Planck Institute for Biogeochemistry Department Biogeochemical Processes Hans-Knoell-Str. 10 07745 Jena Germany
    c University of Berne Geographic Institute Hallerstrasse 12 3012 Berne Switzerland

Abstract

Phosphate release kinetics in soils are of global interest because sustainable plant nutrition with phosphate will be a major concern in the future. Dissolution of phosphate-containing minerals induced by a changing rhizosphere equilibrium through proton input is one important mechanism that releases phosphate into bioavailable forms. Our objectives were (i) to determine phosphate release kinetics during H+ addition in calcareous soils of the Schwäbische Alb, Germany, and to assess the influence of (ii) land-use type (grassland vs. forest) and (iii) management intensity on reactive phosphate pools and phosphate release rate constants during H+ addition. Phosphate release kinetics were characterized by a large fast-reacting phosphatepool, which could be attributed to poorly-crystalline calcium phosphates, and a small slow-reacting phosphate pool probably originating from carbonate-bearing hydroxylapatite. Both reactive phosphate pools—as well as total phosphate concentrations (TP) in soil—were greater in grassland than in forest soils. In organically fertilized grassland soils, concentrations of released phosphate were higher than in unfertilized soils, likely because organic fertilizers contain poorly-crystalline phosphate compounds which are further converted into sparingly soluble phosphate forms. Because of an enriched slow-reacting phosphate pool, mown pastures were characterized by a more continuous slow phosphate release reaction in contrast to clear biphasic phosphate release patterns in meadows. Consequently, managing phosphate release kinetics via management measures is a valuable tool to evaluate longer-term P availability in soil in the context of finite rock phosphate reserves on earth.

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Copyright © 2013. Copyright © by the Soil Science Society of America, Inc.