Conventional Tillage
Conventional tillage (i.e., mouldboard, chisel) is being replaced by lower disturbance, higher residue tillage systems on many farms. Fall primary tillage is preferred by some producers on clay or clay loam soils so that spring tillage establishes a suitable seedbed. However, keep spring secondary tillage to a minimum to preserve soil moisture, minimize the risk of crusting, and reduce the risk of heavy spring rains causing serious soil erosion. A granular, well-aggregated seedbed that provides good seed-to-soil contact is preferred to a fine seedbed.
Reduced Tillage and No-Till
Seeding canola with reduced tillage and no-till systems can be successful if the seeding equipment can place the seed below the residue and in firm contact with the soil. The foundation for successful no-till seeding begins with residue management at harvest in the year prior to seeding canola. If crop residue (straw and chaff) is not spread uniformly, seeding equipment may not achieve good seed placement and seedlings will have difficulty emerging through a mat of residue.
Some tillage tools will disturb residue, disrupt habitat for slugs, and distribute straw and chaff evenly to aid in seed placement. Seed-firming wheels on the no-till drill should press seed into the bottom of the shallow seed trench to ensure adequate seed-to-soil contact. No-till seeding into most residue types works, including corn stalks if the appropriate and properly adjusted equipment is used.
The greatest risk to canola in high residue environments is slug damage. Slugs are often underestimated and damage in canola is typically more severe than in other field crops. They chew off the growing point shortly after emergence, killing seedlings and causing significant stand loss.
It is not recommended to seed winter canola into residue because the plants will set their crowns (growing point) above the residue (Figure 1). Plants with crowns tucked close to the soil surface will have improved winter survival compared to plants that set their crowns above the soil surface or above residue in the field. High crowns are not a concern in spring-planted canola.
Figure 1. Canola growing through thick residue sets crowns above the residue increasing the risk of winterkill.
Seedbed Conditions
Stand establishment challenges are often related to poor seedbed preparation, cloddy seedbeds, dry soil conditions and/or crusting. Canola seed is small compared to most other field crops. The limited food reserves of small seeds means that the time from germination to emergence must occur rapidly to ensure adequate plant stands. Optimizing seedbed conditions and seed placement can reduce early season stresses.
The seedbed should be level, firm, and crumbly with soil moisture in the top 2.5 cm (1 in.). A firm seedbed will help hold moisture near the surface and aid in uniform planting depth and uniform emergence. A crumbly soil with a minimum of 30% residue cover will resist crusting after pounding rains, allowing the tiny seedlings to emerge. The crust can break the hypocotyl arch (the seedling stem) that lifts the cotyledons above the soil surface.
Packing
Soil conditions will determine whether to pack the seedbed before or after seeding. Packing before seeding can help level and firm the seedbed, improving seeding depth control and reducing soil moisture loss. Packing after planting can improve emergence and yield if the soil is prone to drying out before crop emergence. Packing after seeding may bury the seed deeper if the seed row was ridged by seeding equipment and can increase risk of crusting when followed with pounding rains.