Optimal source, placement and application timing for yield and reduction of greenhouse gas footprint for canola production on light texture soils

Project Summary

Nitrogen fertilizer is one of the greatest operational costs to producing canola. It can result in production increases, but it can also produce greenhouse gases nitrous oxide (N₂O) and ammonia (NH₃). For more efficient use of nitrogen fertilizer, reduction in nitrogen losses is required.

Growers are faced with practical challenges of applying nitrogen fertilizer in the fall and uncertainty of whether enhanced efficiency fertilizer products that carry a price premium are worth purchasing. Many growers are also faced with tight schedules for planting are opting to shallow band or even surface place nitrogen fertilizer, though these are not current recommended practices. Some growers are experimenting with in-season nitrogen fertilizer applications but don’t know if it worth the extra management consideration or what rates, application method and fertilizer source to use.

The current project attempts to help address these grower challenges. It builds upon previous work using 4R Nutrient Management to optimize the rate, source, placement and timing of nitrogen fertilizer addition to canola for improved profitability and reduced greenhouse gas emissions. Using six field trials, this project will seek to answer these questions:

• How does surface application of double inhibitor granular urea (SuperU) compare to shallow banding of granular urea and the recommended placement of deep banding of urea?
• Is there an advantage in using SuperU or controlled release granular urea (ESN blend) compare to granular urea when shallow banding?
• Is there an advantage to inhibiting nitrification (eNtrench, and new product, DMPSA) when deep banding granular urea?
• Can enhanced efficiency granular urea products and band placement of fall applied nitrogen match the benefit of spring application of nitrogen?
• Is there an advantage to splitting nitrogen application to at planting and in-season compared to just at planting?
• Does it matter if in-season nitrogen dressing of UAN is top-dressed by surface streaming or side-dressed by injection?
• Is there a benefit of using the new ammonia volatilization inhibitor, Anvol, to top-dress UAN?

This project aims to provide a solution to mitigate emissions from canola and thus yield losses on light texture soil (the soil most prone to emissions). The project uses combinations of integrated best management practices considering all 4R Nutrient Management components. Reduction of N₂O and NH₃ emissions from canola production will contribute to achieve the greenhouse gas (GHG) reduction goal for the Canadian agriculture sector and lower the environmental footprint for canola production in Canada.

There are seven main objectives to this project aimed to improve nitrogen use efficiency of fertilizer for canola production. This project aims to inform which of the following practices perform better for yield and reduction of nitrogen losses on light texture soils:

• Placement: how does surface application of double inhibitor granular urea (SuperU) compare to shallow banding of granular urea and the recommended placement of deep banding of urea?
• Nitrogen source for shallow banding: is there an advantage in using SuperU or controlled release granular urea (ESN blend) compare to granular urea when shallow banding?
• Nitrification Inhibition for deep banding: is there an advantage to inhibiting nitrification (eNtrench, and new product, DMPSA) when deep banding granular urea?
• Fall and spring application: can enhanced efficiency granular urea products and band placement of fall applied nitrogen match the benefit of spring application of nitrogen?
• Split application: is there an advantage to adding nitrogen at planting and in-season compared to just at planting?
• Placement of in-season nitrogen: does it matter if in-season nitrogen dressing of UAN is top-dressed by surface streaming or side-dressed by injection?
• Inhibiting ammonia loss with top-dressing: is there a benefit of using the new ammonia volatilization inhibitor, Anvol, to top-dress UAN?

So far (between October 2018 and March 2020), fall, spring and in-season treatments at two farmer fields near St. Claude, MB have been implemented. Each site had 224 plots (28 treatments for 1X and 0.7X recommended nitrogen rates, with four replicate plots per treatment). Soil was sampled at various times during the study for extractable inorganic nitrogen and above ground biomass and grain yield were determined. For GHG monitoring:

• N₂O gas losses were collected during the growing season for 1X recommended nitrogen application rates and the 0% nitrogen check.
• NH₃ gas losses during the growing season were monitored for 1X recommended nitrogen application rates and the 0% nitrogen check.

The researchers also determined canola canopy spectral reflectance using Crop Circle, Green Seeker and multispectral UAV drone, processed the canola canopy spectral reflectance data and analyzed N₂O gas samples and processed data for flux estimates.