Broadcast seeding cereal and oilseed crops with fertilizer spreaders is becoming increasingly popular, especially where excess moisture is a concern.
Broadcast seeding generally produces lower yields than drill-seeded crops. Thinner stands are usually the result of poor seed-to-soil contact, seeds that are covered too deeply, birds feeding on seeds that are not properly incorporated and more competitive weeds. Higher seeding rates can increase yields but also increase costs.
Unless adequate moisture is available for
rapid germination and emergence, broadcasted seed is often slower to emerge because of poor seed-to-soil contact. Delayed germination and emergence can reduce tillering and delay maturity so that grain filling occurs later in the growing season under less productive conditions. It is the combination of poorer stands and delayed emergence that puts broadcast seeding at risk of lowering yields.
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Despite the challenges, broadcast-seeded crops can be worthwhile in some years. For cereal crops such as wheat, the ability to produce additional tillers, more seeds per head and larger seed under less crowded conditions can compensate for lower germination levels.
Ensure the soil is firm to allow the seed to be placed relatively shallow during the subsequent incorporation. Broadcasting into a loose, fluffy seedbed causes a wide range of final seed depths, resulting in uneven germination.
For those attempting to broadcast canola, consider the following steps:
- Increase seeding rates slightly to compensate for non-uniform seed depth.
- Consider lightly cultivating at a depth of two to four centimetres or harrowing to incorporate the seed into the soil if soil conditions allow.
- Avoid creating lumps during cultivation or straw piles with harrows or cultivators.
- If broadcasting fertilizer as well as seed, be aware that broadcast phosphorus is only about half as efficient as banded phosphorous.
Broadcasting comes with a greater risk of denitrification on saturated soils, reducing nitrogen fertilizer efficiency. Adjust rates accordingly, keeping in mind a realistic target yield based on the time of year and field conditions.
Packing after seeding and incorporation may improve the chances of success. If mixing canola with a fertilizer formulation, such as 11-51-0, try to do so immediately before planting. However, experience has shown that seed viability is not extensively damaged if seeding is delayed for a few days because of adverse weather, as long as the mixture is stored under dry conditions.
