Measuring Nitrous Oxide Emission

This research aims to determine which sources and placement of N show consistent reductions in N₂O emissions. This will help farmers guide management practices that reduce N₂O emissions per unit of crop produced without reducing yield. Practices that reduce N₂O emissions have an added benefit since they also tend to increase nitrogen use efficiency.

Urea and eNtrench NXTGEN™ (urea treated with Nitraphyrin) were either broadcast, shallow banded, or deep banded during seeding (Figure 1). Gas collection chambers were inserted 5 cm into the soil between seed rows a day before the first sampling and left in place from seeding through soil freeze-up to capture representative emissions of the fertilized and unfertilized bands. Gas samples were collected one to three times per week, sampling more frequently after N application. Concentrations of N₂O were determined using a gas chromatograph equipped with an electron capture detector.

Figure 1: Plot map detailing the types of fertilizer and placement methods in the canola field.

We found a consistent reduction in N₂O emissions from canola production through use of the eNtrench NXTGEN nitrification inhibitor compared to urea alone, but a variable response to placement. Banding of urea decreased emissions in drier years, but increased them in wetter years. Shallow sub-surface banding of urea tended to produce higher emissions than deep. Nitrogen placement did not alter the ability of eNtrench to reduce emissions.

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