Closing the yield gap in Canadian spring wheat production
Many factors impact a wheat crop’s ability to reach its full yield potential. Common culprits include nutrient deficiencies, water stress, suboptimal seeding management, poor genetic selection, soil quality and pests. Like many invisible weights dragging down on the productivity of each plant, these factors chip away at the crop’s yield, resulting in a lower actual yield. The difference between the actual yield and the yield potential is known as the yield gap.
Some factors that reduce yield are out of a farmer’s control. The most obvious of these factors is rainfall. Some factors reducing yield are also socioeconomic. Socioeconomic factors include a lack of access to agronomic information, risk aversion, time resources and available credit. If a disease impacts crop health but a farmer chooses not to spray fungicide based on incorrect agronomic information, the yield gap expands. Some of these factors are purely management decisions that are not ideal for the variety and the environment.
So why is this important to you as a farmer? Closing the yield gap can help increase farm profitability and land use efficiency. The differences between actual yield and yield potential in rainfed areas in Western Canada are 34 per cent1. Completely closing the yield gap can have economic implications. Some of the best wheat production areas in the world produce 70 to 80 per cent of yield potential2. Achieving yields higher than this range is challenging as the costs associated with increasing yields incrementally above this level are often uneconomical.
It is possible to narrow the yield gap by aligning best management practices with the appropriate genetics for the environmental conditions in a specific growing region. From a farm perspective, the value of understanding yield gaps becomes clear when we observe the concept from a genetic by environment by management (GxExM) perspective.
GxExM is the idea that when making changes in either genetics, environment, or management, the impacts will depend on which genetics, management, or environment is already in place. All three of these factors are tied together. A simple example could be that Variety B performs better than Variety A in higher rainfall regions. That is a GxE interaction. We can further complicate this and add a management factor. Variety A performs better than Variety B in high rainfall regions only when a fungicide is applied. When a fungicide is not applied, Variety B performs better than Variety A.
The production system in which we produce crops is extremely complex. We are a long way from being able to list the exact management practices that should be implemented on a specific variety in a specific growing region.
Research indicates increasing yield potential is an important factor in increasing actual yields3. Selecting newer varieties and implementing best management practices (early seeding, high seeding rates, reduced weed pressure, appropriate fertility, etc.) may put a farm in a position to increase its actual yield, narrowing the yield gap.
When implementing a new practice or questioning a long-standing practice, consider it from a GxExM perspective. Ask yourself, “How might this practice interact with the variety that I grow and the environmental conditions I typically see?”.
Management practices such as fungicide application, plant growth regulators, specialty fertility products or techniques and even variety selection may be impacted by regionally specific environmental conditions. Where possible, farmers should investigate research related to specific practices on specific varieties in their growing region. Or run randomized and replicated on-farm trials to see farm-specific results. Work with an experienced agronomist to make sure the data you are collecting is sound and should affect your management decisions.
Finally, stay updated with relevant research information. The Alberta Wheat and Barley Commissions, Alberta Innovates BioSolutions, SaskWheat and Manitoba Crop Alliance are co-funding research led by Dr. Brian Beres from Agriculture and Agri-Food Canada and his colleagues at Kansas State University. This research team uses the Global Yield Gap Atlas methodology to establish yield gaps in Canadian Western Red Spring wheat fields across the Prairies. Information from this research will help farmers understand what practices may be causing a yield gap and what can economically narrow the gaps.
1 Brian Beres, Patricio Grassini, Aiden Sanden, & Romulo Lollato. (2022, February 23). Wheat yield gaps in the Canadian Prairies: Magnitude, implications, and opportunities [Presentation]. Top Crop Summit.
2 Lobell, D. B., Cassman, K. G., & Field, C. B. (2009). Crop Yield Gaps: Their Importance, Magnitudes, and Causes. Annual Review of Environment and Resources, 34(1), 179–204.
3 Fischer, T., Byerlee, D., & Edmeades, G. (2012). Crop yields and food security: Will yield increases continue to feed the world?