Discovering the optimal rate of a dual-inhibitor N-fertilizer for maximum N2O emissions reduction

Term: 3 years, ending March 2025
Status: Completed
Researcher(s): Reynald Lemke, Agriculture and Agri-Food Canada
SaskCanola Investment: $27,605
Total Project Cost: $276,050
Funding Partners: Agriculture Development Fund, Western Grains Research Foundation, Sask Wheat

Project Description

Consumers are increasingly concerned about the safety and sustainability of agricultural production practices. In response, many corporations now require suppliers to demonstrate the sustainability of their products and practices. In view of the urgent need to limit greenhouse gas emissions to the atmosphere in an effort to avoid dangerous climate change, greenhouse gas (GHG) emissions have become a key sustainability metric for agricultural products and an important consideration in the marketplace. This is of particular importance for the agricultural industry in Saskatchewan which contributes more than 80% of the province’s total N2O emissions. The great majority (~88% ) of these emissions are directly related to the use of N fertilizers (Environment Canada, 2018). Thus, there is an ever increasing need to identify practical tools that Saskatchewan producers can employ to help them to maintain or improve yields while simultaneously reducing N2O emissions; and to be able to quantify those benefits in a credible, verifiable manner.

Objectives

1. Determine the maximum N2O emissions-reduction that can be achieved with a dual-inhibitor N-fertilizer as compared to urea.

2. Determine maximum N-rate reduction possible with dual-inhibitor N-fertilizer that maintains optimal yields of canola and wheat.

3. Determine the agri-environmental optimum N rate for urea and a dual-inhibitor N-fertilizer as an N source for canola.

Grower Benefits

• GHG emissions have become a key sustainability metric for agricultural products and an important consideration in the marketplace. Thus, there is an ever increasing need to identify sustainable fertilization practices that Saskatchewan producers can employ to help them to maintain or improve yields while simultaneously reducing nitrous oxide (N2O) emissions; and to be able to quantify those benefits in a credible, verifiable manner.

• The results of this study confirmed that nitrous oxide emissions from fertilizer use can be substantially reduced by employing a product that combines urea with a dual-inhibitor (DI) (urease and nitrification inhibitors) compared to untreated urea at equivalent rates of N application.

• Further, N2O emissions reductions can be achieved by reducing the application rate of a DI product. The deepest reductions, up to 80% lower than emissions from urea at the recommended rate, were achieved when the DI application rate was reduced by 30% compared to the recommended rate of untreated urea. However, although infrequent, statistically significant seed yield reductions were observed at the 70% N application rate.

• Based on results from this study, we would conclude that a 20% reduction in application rate with a DI product could achieve maximum emissions reductions, ranging from at least 30% to as high as 79%, without incurring a statistically significant seed yield penalty.