Premium
Nitrification of Anhydrous Ammonia Related to Nitrapyrin and Time‐Temperature Interactions 1
Author(s) -
Gomes S. L.,
Loynachan T. E.
Publication year - 1984
Publication title -
agronomy journal
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.752
H-Index - 131
eISSN - 1435-0645
pISSN - 0002-1962
DOI - 10.2134/agronj1984.00021962007600010003x
Subject(s) - anhydrous , nitrification , loam , ammonium , chemistry , ammonia , nitrogen , zoology , leaching (pedology) , soil water , soil science , environmental science , biochemistry , organic chemistry , biology
The effects of time and temperature, with and without nitrification inhibitor, were evaluated on the rate of nitrification for field‐applied anhydrous ammonia on a Webster clay loam soil (fine loamy, mixed, mesic Typic Haplaquoll) in central Iowa. The purpose of the study was to document factors influencing the production of oxidized N, forms of N more easily lost from the soil by leaching or denitrification. Anhydrous ammonia at 180 kg N/ha was applied at three application dates in the fall of 1979 (9 October, 27 October, and 14 November) and three application dates in the spring of 1980 (15 April, 2 May, and 25 June). Plots with and without 0.56 kg/ha nitrapyrin were established on each date. Ammonium was found to be concentrated within a 5‐cm radius of the injection zone. The accumulation of heat units (HU), calculated by the summation of temperature (°C) multiplied by time (days), was shown to have a negative correlation with recoverable NH 4 ‐N and followed the equation: %NH 4 ‐N = −0.07 HU + 76.4, R 2 = 0.84*, significant at the 0.05 level. Thus, much of the variability of recovered NH 4 ‐N could be explained by a time by temperature interaction. This suggests that a grower's decision to apply anhydrous ammonia in the fall when soil temperatures reach a given level, commonly 10˚C, should be tempered by the date. In early fall, more time is available for nitrification to occur before freezing of the soil, and a greater conversion of NH 4 ‐N to N0 3 ‐N would be expected. In the presence of a nitrification inhibitor, higher percentages of NH 4 ‐N were recovered for a similar heat‐unit accumulation. Regression equations predicted an 84% recovery with 233 accumulated heat units in the presence of nitrapyrin, compared with a 60% recovery without nitrapyrin. For an equal percentage of NH 4 ‐N recovery the following spring, a grower could apply anhydrous ammonia earlier in the fall if nitrapyrin was used. According to the equations developed in this study for the 1979‐1980 season, a 9 October application of anhydrous ammonia with nitrapyrin would have resulted in approximately a 70% NH 4 ‐N recovery in the spring of 1980, compared with the same recovery for a 23 November application without nitrapyrin.