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Agronomy Journal Abstract -

Potassium Azide as a Nitrification Inhibitor1


This article in AJ

  1. Vol. 62 No. 5, p. 595-599
    Received: Oct 24, 1960

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  1. T. D. Hughes and
  2. L. F. Welch2



The effect of 0, 2, 4, 8, 16, and 32 ppm KN3 on nitrification in soil was studied at 30 and 10 C. At both temperatures, KN3 was an effective nitrification inhibitor. At 30 C, 75 ppm of added NH4 + disappeared in 2 weeks where no KN3 had been added as compared to 4 weeks at the 32 ppm KN3 rate. At 10 C, 4 weeks were required for the NH4 to disappear at 0 ppm KN3) whereas more NH4+ was present after 18 weeks than initially where 32 ppm KN3 was applied. Concentrations of (NO2- + NO3-)- N were found to be similar at all KN3 rates once the NH4+ had disappeared. This indicates that KN3 had no effect on mineralization-immobilization relationships. The soil pH for both incubation temperatures was 6.8.

The effect of 4 ppm KN3 in soil incubated at 30 C was studied at soil pH levels of 4.5, 6.0, and 7.5. The NH4-N and (NO2- + NO3-)-N concentrations during 4 weeks incubation indicated that KN3 did not inhibit nitrification at soil pH levels of 4.5 and 6.0 but that nitrification was inhibited at pH 7.5. At 30 C, KN3 does not appear to be an effective nitrification inhibitor for soils of pH less than 6.0.

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