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

Sequestration of Phosphorus-Binding Cations by Complexing Compounds is not a Viable Mechanism to Increase Phosphorus Efficiency


This article in SSSAJ

  1. Vol. 77 No. 6, p. 2050-2059
    Received: May 04, 2013
    Published: October 18, 2013

    * Corresponding author(s): fien.degryse@adelaide.edu.au
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  1. Fien Degryse *a,
  2. Babasola Ajiboyeb,
  3. Roger D. Armstrongc and
  4. Mike J. McLaughlind
  1. a School of Agriculture, Food and Wine The Univ. of Adelaide PMBI Waite Campus Glen Osmond, SA 5064, Australia
    b School of Agriculture, Food and Wine The Univ. of Adelaide PMBI Waite Campus Glen Osmond, SA 5064, Australia current address: BHP Billiton Marketing Asia Pte Ltd. 10 Marina Blvd. no. 05-01 Marina Bay Financial Centre Tower 2 Singapore 018983
    c Dep. of Primary Industries PB 260 Horsham Vic 3400, Australia and Dep. of Agricultural Sciences La Trobe Univ. Melbourne, Vic 3086, Australia
    d School of Agriculture, Food and Wine The Univ. of Adelaide PMBI Waite Campus Glen Osmond, SA 5064, Australia and CSIRO Land and Water CSIRO Sustainable Agriculture Flagship PMB 2 Glen Osmond, SA5064, Australia


There is increasing interest in enhancing the efficiency of P fertilizers or mobilizing fixed P from soil. Cation-complexing ligands are claimed to increase availability of fertilizer-applied or soil P through sequestration of cations (Fe, Al, Ca) that bind P strongly. We assessed the effect of ligand addition on mobility and availability of P in four soils, using a large range of cation-complexing compounds, in batch experiments without or with added P, and found only small effects of these compounds on P solubility. Selected compounds, including two commercial polymer coatings, coated on granular monoammonium phosphate (MAP) and an organic-complexed form of single superphosphate (SSP) fertilizer were tested in diffusion experiments and in a pot trial and compared with conventional MAP or SSP. The ligand treatments, at a 1% coating rate on granular fertilizers, did not significantly affect P diffusion. The only significant difference was between the MAP and SSP treatments, with a lower rate of diffusion from SSP, presumably because of enhanced Ca–P precipitation. Only at very high, commercially unrealistic coating rates (up to 100%) of a dicarboxylic copolymer did P solution concentrations close to the granule increase in an Oxisol, but not in a calcareous soil. The pot trial also showed no effect of the ligand treatments at a 1% coating rate in any of the three soils tested. These results, as well as theoretical considerations, indicate that complexation of P-binding cations is unlikely to be an economically viable process to either release P from stored forms in soil or to increase efficiency of added fertilizer P.

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