The architecture of the oat panicle* is such that oat kernel are in a more fragile situation at maturity compared with wheat and barley etc. Wind will rattle the top of the oat crop and while some oats may hold on longer than others, branches will break and seeds will fall.
In order to avoid losses from this shattering of the panicle, oats are often swathed, and then threshed by a combine with a pickup attachment. This method of harvest will also result in the ending of further growth and then bringing the crop to an even maturity in fields where ripening is variable.
Swathing of oats should start when the kernel moisture content is about 35%. At moisture levels above 35% yield, groat yield and test weight can be negatively affected. Oats are usually ready to swath when the panicle has turned yellow or brown, even as some stems still may show some green color and the least mature kernels have changed from green to cream.
* ”Panicle: a loose, branching cluster of flowers, as in oats”
RESEARCH PAPER (2005): Canadian Journal of Plant Science (2005) 85: 839-846
“Oat quality and yield as affected by kernel moisture at swathing”
William E. May1, Ramona M. Mohr2, Guy P. Lafond1, and F. Craig Stevenson3.
- Agriculture and Agri-Food Canada, Indian Head Research Farm
- Agriculture and Agri-Food Canada, Brandon Research Centre
- Private Consultant
“Oat grown in western Canada is typically swathed and then combined. If the oat crop is swathed too early, seed yield and quality decline; however, if swathing is delayed, harvest losses increase.”
In this study, conducted during 1997 to 2000, 2 locations were used: one in Manitoba and one in Saskatchewan. The locations were: Brandon and Indian Head.
Calibre and AC Assiniboia were the varieties of examination, and the oat crop was swathed at 5 levels of seed moisture content: 50, 41, 32, 23 and 14%.
RESULTS AND DISCUSSION:
“There was an increase in yield as swathing was delayed with most of the yield increase occurring between a kernel moisture of 50 and 41%. Therefore, a kernel moisture content of 41% or less resulted in highest yields.“
“Kernel weight, plump seed and groat yield were optimized when kernel moisture was between 36 and 30% moisture content.
“After 30% kernel moisture was reached, no improvement in oat yield and quality occurred when swathing was delayed any further.”
Caution should be applied when considering the application of glyphosate shortly before the harvest of your oat crop.
While being a popular management tool for oat production, weed control and the harvest operation, some concerns have been raised regarding effects on the integrity of the oat groat.
Further research is being conducted in western Canada to look into this topic. It is clear however, even noting the guidelines on the timing of a glyphosate application, that the use of the product requires information and care.
The acceptance of oat grain may be declined if the crop was sprayed with glyphosate.
Seed from fields that have been treated with a pre-harvest application of glyphosate should not be saved for seed.
The swathed oats should be threshed as soon as they reach an appropriate moisture. Straight cutting should not commence until all the oats have ripened as discounts will be made to seeds with green hulls. An alternative is to cut around the less ripe areas in a field and harvest these areas at a later date. Oats that are left too long in the field can weather and result in lower quality. If oats have been left to straight cut, weather may cause the stems to break down resulting in yield loss. As well, ripe oats are highly susceptible to shattering in heavy rain storms or wind.
Combine cylinder or rotor speed and concave clearances should be adjusted to produce a sample that does not contain de-hulled oats as these may result in the sample being down-graded. Hull-less oats are highly vulnerable to cracking and damage. Care must be taken to properly set the combine to avoid damage. This may require a further reduction in cylinder or rotor speed.
Oat buyers discount grain with high amounts of de-hulled kernels at delivery. Aim for much less than 5% dehulled oats through the harvest, storage/handling and delivery.