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This article in AJ

  1. Vol. 70 No. 5, p. 704-708
    Received: Feb 11, 1978

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Effectiveness of Nitrapyrin in Controlling Nitrification of Fall and Spring-Applied Anhydrous Ammonia1

  1. L. L. Hendrickson,
  2. L. M. Walsh and
  3. D. R. Keeney2



Fertilizer N applied in the fall for the next growing season is often less efficient than N applied closer to the time of plant use. Efficiency might be greatly improved by maintaining the N as NH4 through the use of the nitrification inhibitor, Nitrapyrin [2-chloro-6(trichloromethyl)pyridine] (NI). To evaluate this hypothesis, field trials were established during 1975 to 1977 in south central Wisconsin using 84 to 168 kg/ha N applied as anhydrous ammonia with and without 0.55 kg/ha NI. Nitrogen was applied in early or late fall, or just prior to planting corn (Zea mays L.). The soil sampling data showed that NI provided excellent control of nitrification on the site from which yields were obtained. By early Mac more than 50% of the fall-applied NH3 was still in the NH4 form when treated with NI, while more than 80% was nitrified in the untreated bands. Despite the rapid nitrification of untreated NH4 at this site, little inorganic N was apparently lost from the rooting zone. Therefore no yield or N uptake response by the crop to NI was obtained. Nitrapyrin was much less effective in controling nitrification on a poorly-drained site adjacent to the yield trials. Soil at this site also had higher pH and organic matter, and we found large inorganic N deficits in the sampled zone. These deficits, which can likely be attributed to denitrification, were significantly reduced by NI treatment.

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