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Soil Science Society of America Journal Abstract -

Partitioning Dissolved Inorganic and Organic Phosphorus Using Acidified Molybdate and Isobutanol


This article in SSSAJ

  1. Vol. 56 No. 3, p. 762-765
    Received: Apr 24, 1991

    * Corresponding author(s):
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  1. K. Jayachandran,
  2. B. A. D. Hetrick and
  3. A. P. Schwab 
  1. Dep. of Plant Pathology
    Dep. of Agronomy, Throckmorton Hall, Kansas State Univ., Manhattan, KS 66506-5502



Quantification of P-mineralization rate in soil using isotopic dilution requires that soluble inorganic 32P (32Pi) be determined without interference from soluble organic 32P (32Po). Therefore, a method is needed to partition 32Pi and 32Po into physically separate solutions before radiation counting. A previously suggested method of extracting Pi into isobutanol with acidified molybdate was tested for efficiency of separation from Po. Inorganic P as KH2PO4 was completely recovered in the isobutanol phase with acid molybdate. Organic P (glycerophosphate) remained in the aqueous phase during the extraction. No Po hydrolysis was observed when sodium phytate, glycerophosphate, ribonucleic acid, adenosine 2′- and 3′-monophosphate, and cytidine 2′- and 3′-monophosphate were extracted, but detectable amounts of adenosine 5′-triphosphate hydrolyzed. This technique was tested on four Kansas soils, and the levels of inorganic and organic P obtained by this method were the same as those detected by conventional analyses.

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