Weed control is essential to canola profitability. Without weed control, all other major inputs will not pay off. Higher seeding rates of canola, higher fertilizer rates or better genetics cannot overcome the weed competition.
This study was a two-part economic analysis of data from recently completed field studies, the Canola Grower Survey of canola growers (study 7.9), and secondary sources for prices, input costs and other financial data. This project did not have any field experiments.
The first part, the input study, evaluated different rates of input use – specifically, seed type, seeding rate, fertilizer, and herbicide – used in canola production. Differing rates for inputs were examined in isolation (i.e. changes in single inputs) as well as in combination (i.e. examining multiple inputs simultaneously). Key findings were:
- In a barley-canola rotation, the primary input that influenced yield was weed control. Without weed control, the addition of genetics, a higher seeding rate and nitrogen fertilizer had no impact on net return.
- The most expensive input to eliminate was herbicides, but in this study, using a 50 percent herbicide rate had a similar net return to using the full herbicide rate. The herbicide savings when reducing rates were about equal to the loss in yield from any additional weed competition.
- Reducing the seeding rate and 50 percent of the nitrogen application did not reduce the net return. Lowering the genetics, especially going away from hybrid canola, reduced the net return.
- Nitrogen fertilizer increased net return in a weed-free environment, but a high rate of nitrogen was not necessarily profitable.
- A higher than recommended seeding rate to increase plant density reduced net return.
The second part, the rotation study, examined the economic costs and benefits of shortening the interval between canola in crop rotations. This was only relevant for areas free of clubroot.
When seeding canola cultivars that are susceptible to blackleg, a longer duration between canola (four-year rotation) was more profitable. When growing hybrid canola with blackleg resistance, there was an economic incentive to shorten the rotation and include field pea in a three-year rotation of pea-canola-wheat. When growing canola hybrids with blackleg resistance, two-year canola rotations were as profitable as four-year rotations, especially when canola price was high compared to wheat.
Continuous canola had the lowest return of the five rotations.
There are concerns about disease pressure, even with the blackleg resistance hybrids, when shortened canola rotations are used for many years, so there is a need to have flexible rotations and have some time periods when canola is not planted too frequently.
Principal investigator: Elwin Smith, Agriculture and Agri-Food Canada, Lethbridge, AB
Collaborators: Robert Blackshaw, Stu Brandt, Neil Harker, Eric Johnson,
Published: “Smith EG, Brandt S, Kutcher HR, Malhi SS, Johnston AM. 2013. Economic evaluation of canola and pea interval in rotations. Canadian Journal of Plant Science 93(5): 933-940.”