Seeding deep to chase moisture is rarely a good idea early in the season. In the cool soils of late April and early May, mortality for deep seeded canola can be high and those plants that do reach the surface may not be very vigorous.
But that situation changes with the warm soils of mid to late May. Seeding deeper to hit moisture will hasten germination and crop establishment in fields where the top 1/2″ is too dry to allow germination and emergence.
Here are some tips:
Seed doesn’t have to be IN moisture. ON moisture is OK when seeding deeper, because the additional soil above the seed row slows that moisture loss. Make sure the seed row is well packed to seal in that moisture and prevent further drying out.
Recognize that deeper seeding will increase seed and seedling mortality. Add 10% to the seeding rate to compensate.
Put starter phosphate in the seed row. Keep rates to 20 pounds of actual phosphate per acre, or lower, for seed safety. The nitrogen component of ammonium phosphate can damage seed and seedlings at rates higher than that.
Consider the crusting risk. For heavier soils, a rain before canola emergence could create a crust above the seed row. Because deep seeded canola tends to take longer to emerge, the risk of rain before emergence is higher. Bare soils are more prone to crusting than soils with higher surface residue. With wet conditions, growers may have tilled or harrowed soils that they may not have tilled in the past. In this case, the risk of crusting may be increased relative to past experience.
Heavy rain could also fill in drill runs. Instead of 1.5” of soil cover, it could be 3” if the drill and packer combination creates a deep seed trench that fills with mud after a rain.
Slow down when seeding deep to more closely manage seed depth for all rows. At higher speeds, back rows tend to throw more dirt over the front rows.