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Nitrification Inhibition in Soil: II. Evaluation of Anhydrous Ammonia‐Potassium Azide Solutions in Eastern Washington
Author(s) -
Papendick R. I.,
Parr J. F.,
Smith S.,
Smiley R. W.
Publication year - 1971
Publication title -
soil science society of america journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.836
H-Index - 168
eISSN - 1435-0661
pISSN - 0361-5995
DOI - 10.2136/sssaj1971.03615995003500040029x
Subject(s) - nitrification , anhydrous , loam , chemistry , potassium , zoology , nitrogen , ammonia , soil water , nuclear chemistry , soil science , environmental science , biochemistry , biology , organic chemistry
The effectiveness of potassium azide (KN 3 ) as a nitrification inhibitor for field‐applied anhydrous NH 3 was evaluated on a Naff silt loam in the winter wheat ( Triticum aestivum L.) area of eastern Washington. Formulations of KN 3 in liquid NH 3 of 0, 2, and 6% (w/w) were applied to fallow soil in August 1969 at a rate of 112 kg N/ha (81‐cm spacing) with a special field applicator. The 2% formulation was also applied at a rate of 224 kg N/ha. The NH 3 retention zone was sampled periodically through February 1970 and analyzed for NH 4 + ‐N, NO 2 ‐ ‐N, and NO 3 ‐ ‐N. Both levels of KN 3 were effective in reducing the nitrification rate during the early post injection period, but the higher level was more effective at later dates. Two months after application, the amounts of NO 3 ‐ ‐N recovered from the retention zone as percent of total extractable N were 67, 48, and 36 for NH 3 alone, NH 3 + KN 3 (2%), and NH 3 + KN 3 (6%), respectively. Percentage amounts of NO 3 ‐ ‐N decreased with increase in N application rate. Nitrification inhibition due to KN 3 was still evident 6 months after application, particularly at the high N rate. The inhibitory effect of low soil temperature during the winter months was also apparent. These results indicate that KN 3 formulated with anhydrous NH 3 was an effective nitrification inhibitor for this N source.