Relatively high prices and increasing demand for canola (Brassica napus L.) have prompted growers to produce more canola on more cropland.
Here we determine if canola seed yield and oil concentration can be increased over current levels with high levels of crop inputs.
From 2008 to 2010, direct-seeded experiments involving two seeding rates (75 vs. 150 seeds m2), two nitrogen rates (100 vs. 150% of soil test recommendation), and the presence or absence of polymer-coated nitrogen or fungicides, were conducted at eight western Canada locations in canola-wheat-canola or continuous canola rotations.
Herbicides, insecticides and fertilizers other than nitrogen were applied as required for optimal canola production. Increasing recommended nitrogen rates by 50% increased canola yields by up to 0.25 Mg ha1.
High (150 seeds m2) versus lower (75 seeds m2) seeding rates increased canola yields by 0.07 to 0.16 Mg ha1.
Fungicide treatment or polymer-coated nitrogen blended with uncoated urea increased canola yields by 0.10 Mg ha1 in 2010, but not in 2008.
The highest canola input combination treatment following wheat (3.50 Mg ha1) yielded substantially more than the same high input treatment following canola (3.22 Mg ha1).
Average site yields were influenced by site conditions such as soil organic matter, days to maturity, and temperature, but these site and environmental predictors did not alter treatment rankings.
Using higher than the soil test recommended rate of nitrogen or planting 150 versus 75 seeds m2 increased canola yields consistently across western Canada.
Canola oil concentration varied among canola cultivars, but was consistently low when N rates were high (150% of recommended).
Higher than normal seeding rates led to high canola seed oil concentration in some cases, but the effect was inconsistent.
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