As the calendar is moving into November and oilseed crops are still in the field awaiting harvest, the question becomes what to harvest first, at what moisture content and how to store for long-term quality.

 

When faced with a number of different oilseed crops in the field, the sequence of harvest is important in ensuring that the best quality is achieved and sustained for all crops. For example, sunflowers that are in good shape and disease free can maintain quality better during adverse weather conditions than canola which is lying in the swath. Additionally, some crops that are still standing may need to be swathed in order to protect the quality and reduce grain losses in the future.

 

In general, grain being harvested now is testing tough or high in moisture. It may be necessary to dry the grain down to a moisture content that is safe for long-storage, meaning access to bins with aeration, drying equipment and systems may influence the order of harvest and at what moisture content harvest can begin in individual fields.

If all crops remaining in the field are ready at the same time, consider harvesting the canola first. Even in a protective swath, deterioration of the crop by weather will occur over time. For example, freeze-thaw cycles can cause pod integrity to weaken, allowing the pod to separate and seeds to shell out onto the ground.

 

The Canola Council of Canada recommends that producers make every effort to harvest canola before winter sets in. Molds and a buildup of free fatty acids in the oil can reduce #1 or #2 grade canola to sample grade by spring, resulting in lost dollars for the grower.

 

Canola is considered dry and sellable at 10% moisture. Almost all elevator points will not accept canola if higher than 10%. Canola combined at moisture levels higher than 10% needs to be brought down to a safe storage moisture content. The initial moisture content of the canola crop coming off the field will determine the need for a drying system. Most producers have experience combining damp or tough canola under normal harvest conditions, but we are now in conditions that are not normal and ambient air temperature for drying may not be enough. Keep in mind, canola goes through a “sweating stage” for a period of about six weeks after harvest, where during that time both moisture and temperature can change in the stored grain. Careful monitoring of stored grain is necessary even after the grain is dried to “safe” moisture content.

 

Aeration fans should be turned on as tough grain is being binned, as this will help to remove moisture as the seed is unloaded. The larger the perforated floor area, the more effective the air will move through the small sized and densely packed canola. Try not to over-fill bins, as it may mean the air will not move throughout the entire bulk of grain, which can create pockets of wet canola that could start to mould and heat quickly.

 

Temperature and moisture of the binned canola should be monitored closely and potentially daily to ensure moisture contents are decreasing. With use of aeration, canola at the bottom of the bin (close to the perforations) will be dry faster and can be cooler than canola higher up in the bin. When sampling for moisture and temperature, be sure to separately sample the bottom, middle and top of bin. Be prepared to move the drier canola from the bottom to the top of the bin to aid in more uniform drying of the grain.

 

As daytime temperatures peak at less than 10 C and with high humidity (60% plus), natural air may not be enough to bring the moisture content down to a safe storage level. If moisture is not coming down, consider using batch or continuous air grain dryers. A system of augers, hoppers is necessary when heated-air drying systems are used. This will ensure a continuous flow of grain from the field to the bin.

 

Canola harvested at high moisture contents in late fall where daytime temperature are less than 10C and higher humidity needs to be dried using a heated air drying system to pull moisture out of the grain. Once the moisture levels are brought down to a safe level (8 - 9%) the canola can be put into aeration, for continued conditioning and storage.

 

When using heated air to dry grain, read the user manuals! Over-heating canola while drying, can cause quality issues such as heating or even start fires. As with all farm equipment, caution should be exercised when working around grain dryers.

 

Producers may have to wait for prolonged freezing temperatures in areas where the seed moisture is high and the ground is too wet to support harvesting equipment. This has worked in the past as long as the seed can make it through the sieves to the hopper. The challenge is keeping the sieves clear of ice which can occur as the heat of running the combine thaws the frozen plant material thus releasing moisture onto the sieves which will then freeze and block grain movement.

Flax can withstand weathering conditions better than canola, as the flax bolls are less susceptible to shelling out than are canola pods. Producer comments this fall suggest the flax seed may be mostly dry (less than 10%), but standing stalks are green causing wrapping on the reel. Swathing the crop will allow it to dry down, reducing wrapping problems during combining. As well, swathed flax may be easier to pick-up later this fall or next spring if the need arises. If left un-swathed, the weight of snow on the crop may result in significant stalk breakage and/or lodging. The longer the crop is exposed to freeze-thaw conditions, the more the seed quality and appearance will be reduced. Also, flaxseed overwintered in the field is less suitable for the human consumption market.

 

The moisture content in flax can be reduced with aeration under the right conditions, as with canola, but in late fall, a grain dryer may be more effective in bringing the moisture content down to a storable level. Flax is considered tough from 10.1 to 13.5% moisture and damp if over 13.5% moisture.

 

 

If using aeration and natural air to condition flax, sampling of resulting product is critical. Monitor the changes in moisture and temperature in the bin by sampling the bottom, middle and top of bin separately. Grain at the bin bottom closer to the aeration will probably be dryer than grain at the top of the bin. Move grain from the bin bottom to the to top to provide mixing and evenly reduce moisture throughout the entire bin.

The sellable product is 10% moisture, but for successful long-term storage, targeting 8-9% moisture will reduce chances of heating and spoilage. Even dry, flax is prone to heating because of its high oil content. Stored flax should be routinely monitored to ensure there are no hot spots developing. A hot spot in stored flax can spread quickly - possibly throughout the entire bin.

Long-term sunflower storage is typically targeted around 9-10%, but harvesting sunflowers with higher moisture can result in higher yields, less bird damage and less seed dropping and degrading from diseases. As the fall season progresses, drying is probably mandatory so harvesting can be completed. When sunflower seed is harvested at high moisture (>16%), damage can occur to the seed coat termed as “scuffing”. Friction that removes the seeds from the head also can cause high moisture seed coats to peel off a fine layer of the black shell. This results in the seed coat to look white and resemble damage caused by sclerotinia head rot. The nut meat inside is sound, but the visual appearance of the seed is down-graded when selling to the processor.

 

Sunflower drying with bin, batch and continuous-flow dryers has been used successfully in the past. The large seed size (as compared to canola and flaxseed) allows air to pass easily. As well, sunflowers have lower test weights versus small grains, relatively small quantities of moisture are needed to be removed. Guidelines for drying sunflowers available in the user manual for the specific dryer being operated should be followed closely. There is the possibility with confection sunflowers the high drying temperatures may cause the nutmeats to be steamed, wrinkled or even scorched, which will all down-grade the seed and price.

 

Fire hazards exist in drying sunflowers because very fine hairs or fibers from the seed are rubbed loose during handling and can ignite when drawn through the drying fan and open burner. Keep equipment clean and do not leave unattended while running.

 

The above information is a guideline for managing harvesting of oilseed crops in late fall. Producers need to assess the individual conditions of their crops, moisture contents and availability of aeration and drying equipment to determine their best route for success.