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 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 crop year 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 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. Preliminary analyses of N₂O emissions have been completed for the first crop year of the study in Manitoba. Nitrous oxide concentrations of samples, and statistical analyses for the 2016 crop year will be completed during the spring of 2017. Preliminary statistical analyses have been completed for both cropping years for grain yield of AAC Brandon hard red spring wheat. Grain yield increased as a result of N addition and none of the N sources negatively affected yield. Fall application of N sources did reduce grain yield compared to spring application. This is not unexpected as current recommendations are to increase N rates by 20% for fall additions. Nevertheless, we are surprised to see a fall application yield disadvantage considering the late date of fall application close to soil freeze up.