Sowing plump seed at the right depth is an important first step towards achieving vigorous, healthy seedlings. Planting should be deep enough to provide uniform coverage of the seed and to help maintain moist conditions for germination.
- The recommended depth for most oat varieties is 3-6cm.
Oat seedlings emerge by elongation of the mesocotyl and coleoptile (in wheat and barley it is only through elongation of the coleoptile) so oats can safely be sown deeper than wheat and barley.
Sowing too shallow may:
- Place the seed in dry soil and it may fail to emerge.
- Cause shallow crown depth that may cause the plants to lodge when soil is very wet and in high winds.
Consequences of deep sowing can include:
- Delayed seedling emergence.
- Emerging seedlings that are weaker, limp and easily damaged by wind and insects.
- Reduced root development making plants more susceptible to root diseases.
- Delayed plant development and tillering.
- Reduced competitiveness with emerging weeds.
Use press-wheels to compress the soil directly above the seed for even distribution during seeding. When using standard tyned seeders without press-wheels, the seed is often spread through a depth of 2-3cm with the occasional seed left on the soil surface.
Sowing into water repellent sands early in the season where the wet soil may be at 5cm or more necessitates the use of press-wheels to ensure even establishment.
Coleoptile and mesocotyl length are temperature dependant so early sowing into warmer soils will result in them being longer compared to later sowings in winter.
In cereal crops that receive adequate moisture, narrow row spacing generally results in higher grain yields than wider rows by promoting ground cover, optimising light interception and by suppressing weed growth.
For crops expected to yield greater than four tonnes per hectare (t/ha), rows should be sown no further apart than 25cm and preferably less than 20cm. For hay this will give good ground coverage by plants so that the windrow can be held off the ground to improve air circulation and reduce staining.