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This article in SSSAJ

  1. Vol. 54 No. 6, p. 1763-1767
    Received: Jan 2, 1990

    * Corresponding author(s):


Phosphorus and Aluminum Release from a Spodic Horizon Mediated by Organic Acids

  1. T. R. Fox ,
  2. N. B. Comerford and
  3. W. W. McFee
  1. ITT Rayonier, Inc., Forest Research Center, P.O. Box 819, Yulee, FL 32097
    Soil Science Dep., Univ. of Florida, Gainesville, FL 32611
    Agronomy Dep., Purdue Univ., West Lafayette, IN 47907



The ability of organic acids to affect surface and solution reactions of P and Al in soils containing Al-oxide surfaces is related to their ability to form stable complexes with Al. This study was conducted to determine if the amount of P and Al released following the addition of an organic acid to a Bh horizon soil could be estimated based on the Al stability constant (logKAl) of the organic acid. The release of Al and inorganic P from spodic horizon material increased in the presence of organic acids that form stable complexes with Al. Overall, the logKAl value was a good indicator of the effect of the organic acid on inorganic P and Al release. Among the 16 organic acids studied, release of Al and inorganic P increased exponentially with increasing stability constants. A threshold value of approximately 4.1, however, was required before substantial amounts of inorganic P were released. This value may reflect the stability of P bond to Al-oxide surfaces in this soil. Salicylic acid was a notable exception to the observed trend in release of both Al and P; despite a large stability constant, little inorganic P or Al was released. Although significant amounts of soluble organic P were released in all the organic-acid solutions, the amount of soluble organic P released was not related to the stability constant of the organic acids.

Contribution of the Florida Agric. Exp. Stn., Journal Series no. R-00381.

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