Performance of Two Nitrification Inhibitors Over a Winter with Exceptionally Heavy Snowfall
- R. Jay Goos *a and
- Brian E. Johnsona
Fall application of NH3 for spring wheat (Triticum aestivum L.) is common in the northern Great Plains. Two field sites were established in eastern North Dakota, with the objective of measuring the relative rate of fall and overwinter nitrification as influenced by two nitrification inhibitors, nitrapyrin and ammonium thiosulfate (ATS). Aqua ammonia was injected into the soil in early October 1996, alone, with nitrapyrin (0.56 and 1.68 kg ha−1), or with ATS (17 kg S ha−1). The N rate was 84 kg ha−1 The winter of 1996–1997 was very unusual, with about 3 m of snowfall—three times the average snowfall in southeastern North Dakota. Nitrapyrin and ATS were effective in slowing nitrification in the fall and both inhibitors increased the amount of mineral N found in the fertilizer bands in the spring at both sites. One site was planted to `Pioneer 2375' spring wheat. Overwinter N loss, presumably by denitrification, was severe. Amending the ammonia with nitrapyrin or ATS greatly increased wheat growth, N uptake, and grain yield. The apparent N uptake efficiency into the grain + straw was 24% for the unamended aqua ammonia, but was 50 to 56% when nitrapyrin or ATS was used. These results probably define a worst-case scenario regarding the performance of fall-applied ammonia in this area, and suggest that both nitrapyrin and ATS have value as nitrification inhibitors with fall-banded N.Please view the pdf by using the Full Text (PDF) link under 'View' to the left.
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