Urea Decreases Nitrous Oxide Emissions Compared with Anhydrous Ammonia in a Minnesota Corn Cropping System

Fertilizer nitrogen use is estimated to be a significant source of nitrous oxide (N2O) emissions in western Canada. These estimates are based primarily on modeled data, as there are relatively few studies that provide direct measures of the magnitude of N2O emissions and the influence of N source on N2O emissions. This study examined the influence of nitrogen source (urea, coated urea, urea with urease inhibitor, and anhydrous ammonia), time of application (spring, fall) and method of application (broadcast, banded) on nitrous oxide emissions on two Black Chernozemic soils located near Winnipeg and Brandon Manitoba. The results of this 3-yr study demonstrated consistently that the rate of fertilizer-induced N2O emissions under Manitoba conditions was lower than the emissions estimated using Intergovernmental Panel on Climate Change (IPCC) coefficients. The Winnipeg site tended to have higher overall N2O emissions (1.7 kg N ha-1) and fertilizer-induced emissions (~0.8% of applied N) than did the Brandon site (0.5 kg N ha-1), representing ~0.2% of applied N. N2O emissions in the first year of the study were much higher than in subsequent years. Both the site and year effects likely reflected differences in annual precipitation. The N2O emissions associated with the use of anhydrous ammonia as a fertilizer source were no greater than emissions with urea. Fall application of nitrogen fertilizer tended to result in marginally greater N2O emissions than did spring application, but these differences were neither large nor consistent. Key words: Nitrogen fertilizer, nitrous oxide emissions, nitrate intensity, anhydrous ammonia, urea

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Does 3,4-dimethylpyrazole phosphate or N-(n-butyl) thiophosphoric triamide reduce nitrous oxide emissions from a rain-fed cropping system?

Soil Research ◽

10.1071/sr17219 ◽

2018 ◽

Vol 56 (3) ◽

pp. 296 ◽

Cited By ~ 4

Author(s):

Guangdi D. Li ◽

Graeme D. Schwenke ◽

Richard C. Hayes ◽

Hongtao Xing ◽

Adam J. Lowrie ◽

...

Keyword(s):

Nitrous Oxide ◽

Grain Yield ◽

Crop Yields ◽

Cropping System ◽

N2o Emission ◽

Nitrous Oxide Emissions ◽

Wheat Crop ◽

N2o Emissions ◽

Urease Inhibitors ◽

Eastern Australia

Nitrification and urease inhibitors have been used to reduce nitrous oxide (N2O) emissions and increase nitrogen use efficiency in many agricultural systems. However, their agronomic benefits, such as the improvement of grain yield, is uncertain. A two-year field experiment was conducted to (1) investigate whether the use of 3,4-dimethylpyrazole phosphate (DMPP) or N-(n-butyl) thiophosphoric triamide (NBPT) can reduce N2O emissions and increase grain yield and (2) explore the financial benefit of using DMPP or NBPT in a rain-fed cropping system in south-eastern Australia. The experiment was conducted at Wagga Wagga, New South Wales, Australia with wheat (Triticum aestivum L.) in 2012 and canola (Brassica napus L.) in 2013. Results showed that urea coated with DMPP reduced the cumulative N2O emission by 34% for a wheat crop in 2012 (P < 0.05) and by 62% for a canola crop in 2013 (P < 0.05) compared with normal urea, but urea coated NBPT had no effect on N2O emission for the wheat crop in 2012. Neither nitrification nor urease inhibitors increased crop yields because the low rainfall experienced led to little potential for gross N loss through denitrification, leaching or volatilisation pathways. In such dry years, only government or other financial incentives for N2O mitigation would make the use of DMPP with applied N economically viable.

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