Enhanced Efficiency Fertilizer Technologies to Reduce Nitrous Oxide Emissions from Cropped Soils in Prairie Canada

This Prairie Province-wide project seeks to assess the environmental and agronomic benefits achieved through grower adoption of enhanced efficiency nitrogen (N) fertilizer technologies, applied in the fall or spring. The application of N fertilizers to agricultural land, and resulting emissions of nitrous oxide (N₂O), have been identified as a major driver impeding greenhouse gas reductions for the agriculture sector. It is important to develop methods to reduce N₂O emissions from cropped land after N fertilizer applications. This project is evaluating the benefit of timing N fertilizer application (fall vs. spring), and the use of enhanced-efficiency products (EEF) for urea and anhydrous ammonia N fertilizers for reduced N₂O emissions. In 2015, two sites were successfully conducted comparing fall and spring N treatments for spring wheat. Nitrous oxide emissions were monitored through the growing season and into fall. Soil sampling, as well as moisture and temperature monitoring were also completed regularly and grain yield was determined.

Grain yields were greater with spring compared to fall applications using urea and anhydrous ammonia fertilizers. However, some EEF treatments did result in yields from fall applications being equal to that of spring applications. This research was expanded for the 2016 and 2017 crop years after receiving funding from the Climate Change and Emissions Management Corporation (CCEMC), and the Western Grains Research Foundation (WGRF). This includes one site in Alberta and two sites in Saskatchewan, as well as the two original sites in Manitoba. The research sites have been used each year for outreach (tours) to growers, consultants, ag-retailers, funders and stakeholder events. Several presentations have occurred at multiple conferences and grower meetings. Analyses of N₂O emissions have been completed for the first two crop years of the study in Manitoba, Saskatchewan and Alberta. Statistical analyses for crop yields and N₂O emissions are on-going for the 2017 crop year. The amount and timing of precipitation events greatly interacted with the N fertilizer forms, rates, timing, and placement. The crop years of 2015 and 2016 had similar patterns where two EEF products containing nitrification inhibitors (eNtrench®-treated urea and Super U) had lower cumulative N₂O emissions compared to regular urea, anhydrous ammonia, urea treated with urease inhibitor (Limus®), and nitrapyrin-treated anhydrous ammonia. At the Manitoba sites, the 2017 crop year experienced a wet fall followed by a dry spring. There were much greater cumulative N₂O emissions from the fall applications compared to spring applications. Research samples from all the sites in 2017 are still being analyzed and will be included in a final report later in 2018.