Only about 60% of canola seeds survive to become plants, on average. With the following tips, canola farmers can increase seed survival and get more from their seed investment.
Seed shallow. Half an inch to 1 inch below the packer furrow is the recommended seed depth for canola. This will reduce days to emergence and reduce the seed energy required for emergence.
Seed at a consistent depth. For some drills, the overall average may be one inch, but the range could be zero to two inches. Too shallow or too deep can both contribute to increased seed and seedling mortality, and those seeds that do emerge will have highly variable emergence dates, creating an uneven field. One advantage to planters is consistent seeding depth, which can improve seed survival.
Seed slower. The ideal speed will vary by drill and soil conditions and will balance the need to do a good job with the need to “get things done.” In general, at higher speeds, rear openers tend to throw more soil over the front rows. With seed in these front rows buried deeper, seedlings will be slower to emerge — or the emergence rate will be reduced. Re-check depth when moving from one field to the next.
The Canola Council of Canada’s Ultimate Canola Challenge for 2018 has a seeding speed objective. Find protocols to run your own seeding speed trials at ultimatecanolachallenge.ca. (Direct link to protocols.)If you want to set up a formal trial through UCC, please contact Nicole Philp at firstname.lastname@example.org.
Limit seed-placed fertilizer. Nitrogen fertilizer placed in the seed row can increase seedling loss due to fertilizer toxicity and salt effect. The safest practice is to place only phosphate fertilizer with the seed at rates up to 20 pounds of phosphate per acre. Put the rest with the N and other nutrients away from the seed row. The amount of thinning due to higher rates of seed-placed fertilizer will depend on soil conditions. More moisture, for example, will protect seedlings somewhat from higher rates.
Penetrate residue. Ideally, the combine would have spread residue evenly in the fall to reduce or eliminate the need for tillage. Farmers also want a drill that can penetrate residue so all seeds go into the soil.
Leave a firm seedbed. Openers that fracture the seedbed to place fertilizer lower than the seed may not provide the firm moist seedbed that canola needs. Worn openers that do not provide a defined seed ledge and high fan speeds that cause seed bounce can also reduce an opener’s ability to place seed precisely.
Pack appropriately. In wet conditions, reduce packing pressure to limit hard crusting. In dry conditions, pack more to conserve moisture in the seed row. Packing pressure can be a delicate balance, and often changes by soil type as well as moisture conditions.
Seed into warmer soils. This can greatly increase survival but this needs to be balanced against the benefits of early seeding. Canola seeded early May yields higher, most years, than canola seeded late May, but this yield benefit depends on stand establishment. Canola can emerge in soils as cool as 2°C. Soil temperatures of 5°C or higher with warmer weather in the forecast should facilitate reasonably good rates of emergence. The best plan is to aim to seed early and use the other tips listed above to increase seed survival.
Rotate crops. A tight canola rotation could increase the risk from seed and seedling diseases that can prevent emergence.
A note on seed size. A recent AAFC study “Seed size and seeding rate effects on canola emergence, development, yield and seed weight” (published 2014) led by Neil Harker concluded that: “Seed size effects on canola emergence, yield or seed quality were not significant. Increasing seed size had a positive linear association with early canola biomass and 1,000-seed weights, whereas, both days to flowering and days to the end of flowering had a negative linear association with seed size.
Greater biomass from large seeds increases crop competition with weeds and also hastens flowering, shortens the flowering period and reduces the risk that canola will be exposed to high temperatures that can negatively impact flowering and pod development.”