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This article in SSSAJ

  1. Vol. 35 No. 4, p. 643-647
    Received: Nov 17, 1970
    Accepted: Mar 4, 1971

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Triammonium Pyrophosphate as a Source of Phosphorus for Plants1

  1. J. D. Hughes2 and
  2. Isao Hashimoto3



When ammonium ortho- and pyrophosphates were applied to mixtures of sand and a soil mineral (kaolinite, montmorillonite, or gibbsite), both the uptake of P by plants and the immobilization of the P were affected more by the soil mineral than by any other factor. Pyrophosphate was hydrolyzed to orthophosphate during incubation more rapidly in the presence than in the absence of a soil inoculum. The results tend to support the hypothesis that plants utilize orthophosphate more readily than pyrophosphate. Although the reactions of pyrophosphate with soil minerals differ markedly from those of orthophosphate, the two forms of phosphate were immobilized by the soil minerals to about the same extent, and differences between the two forms disappeared as hydrolysis and immobilization proceeded. The P uptake was in the order control (no mineral) > kaolinite > montmorillonite > gibbsite, in agreement with the extent of reaction of the applied phosphate with these minerals.

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