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Soil Science Society of America Journal Abstract -

Effect of Phenylphosphorodiamidate on Immobilization and Ammonia Volatilization1


This article in SSSAJ

  1. Vol. 51 No. 4, p. 1067-1071
    Received: Apr 18, 1986

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  1. L. L. Hendrickson,
  2. T. E. Omholt and
  3. M-J. O'Connor2



Laboratory incubation experiments were conducted to evaluate the ability of the urease inhibitor phenylphosphorodiamidate (PPD) to reduce NH3 volatilization and immobilization of urea (100 mg N kg−1 of soil). Application of 20 mg PPD kg−1 of soil effectively inhibited urea hydrolysis for approximately 4 d in both soil and oat straw-amended soil systems. This delayed urea hydrolysis reduced NH3 losses after 7 d from 82 to 19% in the straw-amended soil, and from 26 to 14% in the soil system. When urea was applied to soil incubated in closed vessels, only 80% of the applied urea could be recovered as inorganic N after 3 d of incubation. This apparent immobilization of N was prevented for 7 d by application of PPD. Immobilization of N in the straw-amended soil exceeded 40% within 7 d, but the onset of these losses was delayed for at least 3 d by PPD. These results demonstrate that losses of surface-applied urea via both NH3 volatilization and immobilization can be prevented by application of an effective urease inhibitor.

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