More growers may try broadcast seeding this year if excessive spring moisture keeps the drill off the field for too long. Over the long run, canola drilled at 1/2" to 1" deep into moist soil and packed lightly for rapid and uniform emergence will produce the most consistent crop establishment. But when conditions are wet, broadcast seeding may be the only way to get the job done. What’s more, broadcasting is faster than seeding with the drill — especially if the field is full of potholes to work around. And broadcasting could provide better seed placement if the alternative is "mudding in" seed with a drill that has mud caked on the openers, mud plugging the seed runs, and mud wrapped around the packers.
Important tips when broadcast seeding:
Be patient. Seeding anytime before mid May should give canola a good chance to meet its yield potential. By then, broadcast seeding may still be the best solution for some growers faced with continued wet fields, but broadcasting onto warm and moist soils in May should increase the success rate compared to broadcasting in late April.
Increase the seeding rate. Seed germination and seedling survival for broadcast canola could be a lot lower compared to seed drilled into a moist, packed seedbed. A higher seeding rate can compensate. It also provides more margin for error if the seed and fertilizer ratio doesn’t stay consistent as the floater tank empties. A floater with two tanks, one for seed and one for fertilizer, will reduce or eliminate this risk. Consider seed size in grams per 1,000 kernels and estimate seedling survival when setting the seeding rate. Click here for a factsheet with tables that provide seeding rates based on target plant stand, seed weight and estimated seedling survival.
Double the phosphorus rate. Canola plants need early access to phosphorus. When broadcast, phosphate prills and seed are not always close enough for timely access to the fertilizer. Higher phosphate rates will improve the average proximity and compensate for the increased reactions with soil constituents that limit availability.
Seed soon after blending. Fertilizer, especially any kind of nitrogen fertilizer, can start to reduce canola seed germination rates within the first day after blending.
Cultivate or harrow after seeding. Shallow cultivation or harrowing (if conditions are dry enough to avoid mud smearing or bunching of crop residue) will help improve seed to soil contact. Check seed placement as you would behind a drill, to ensure you are getting adequate incorporation while keeping the maximum depth shallow enough to allow uniform emergence.
High residue increases risk. Broadcasting onto fields with high residue may not provide the seed to soil contact for high establishment rates, but cultivating these fields ahead of broadcasting could create an equally inhospitable seedbed, with large clods and a crusted soil surface.
Broadcast N and S. Growers could broadcast their nitrogen and sulphur, and use the drill just for seed and starter phosphorus. That way, they wouldn’t have to fill the seeder tank right full, which could make it possible to get the drill through a field without getting stuck.
Know the rules for crop insurance. Broadcast canola does not automatically quality for crop insurance. The established stand must be inspected and meet crop stand standards before it can be insured. If the crop does not grow and the ground is too wet to seed, the grower could be eligible to receive an unseeded acreage benefit. Rules for unseeded acreage benefits vary by province. In Alberta, for example, growers qualify only if 10% or more of acres in the area remain unseeded.
Source: Canola Council