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This article in AJ

  1. Vol. 70 No. 5, p. 805-810
    Received: Feb 6, 1978

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Effect of Nitrapyrin on Nitrification of Fall and Spring-Applied Anhydrous Ammonia1

  1. J. T. Touchton,
  2. R. G. Hoeft and
  3. L. F. Welch2



Nitrification of ammonium fertilizers in late fall and early spring and subsequent nitrate losses through leaching and denitrification are a continuing economical and environmental concern. To evaluate the effects of nitrapyrin on nitrification, anhydrous ammonia with and without nitrapyrin was applied in the fall and spring to poorly drained soils in southern, central, and northern Illinois. Nitrogen and nitrapyrin rates ranged from O to 268 and O to 1.12 kg/ha, respectively. Detailed sampling from ammonia retention zones was conducted throughout the fall, spring, and summer. Effects of nitrapyrin on nitrification varied with time of application, nitrapyrin rate, and soil type. In central Illinois, nitrification of fall-applied N, with or without nitrapyrin, was relatively rapid in a silty clay loam soil until the soil temperature dropped below 10 C, but less nitrification occurred when nitrapyrin was applied. On similar soil in the northern part of the state, when the soil temperature was below 10 C at application, nitrapyrin was more effective in controlling nitrification. Time required for amonium-N in soil to drop to levels equal to that in the control (no N or no nitrapyrin) increased with N and nitrapyrin rates except with spring-applied N in central Illinois in 1975 where increasing nitrapyrin rates above 0.28 kg/ha had no additional effect on inhibition of nitrification rates. Nitrapyrin applied to a silt loam soil in southern Illinois in the spring or fall of 1975 had no significant effect on nitrification, but nitrapyrin used with spring-applied N in 1976 was effective in controlling nitrification through early June.

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