By Canadian Grain Act standards, canola is considered dry for marketing once the moisture is at 10 per cent or below. However, for long term storage, canola should be at or below 8.5 per cent moisture and 10 C. Just because the grain is considered dry, it doesn t mean that it s safe. The relationship between safe storage moisture and temperature is outlined in Figure 1.
Canola will respire in storage for the first six to eight weeks in storage, and moist pockets can form in the bin. The respiring canola will cause an increase in temperature which, in conjunction with the differences in temperature between the grain in the outside of the bin and the grain in the middle of the bin, can cause moisture migration in the stored grain. The moisture migration patterns differ in the fall from the spring and the details of each are outlined in Figure 2.
The larger the bin size is, the slower the grain temperature inside will adjust to the outside temperature and therefore the more likely than moisture migration will occur within the bin. Therefore, it is important that grain that is recently harvested be cooled to below 15 C as soon as possible and should be below eight per cent moisture for long-term storage.
Because canola is an oilseed, the oil portion is hydrophobic. That means that the oil portion of the seed (approximately 42 to 44 per cent on average) contains very little or no water and so that any moisture in the seed is contained in the remaining meal fraction. This is why canola must be stored at a lower seed moisture content than cereals which are composed primarily of starch and protein. This is why as the oil content of the seed increases, the actual safe storage moisture content of that seed is lower because the resulting meal fraction is lower. Work out of Oklahoma demonstrates this trend (See Figure 3). Although the absolute numbers may change in western Canada from those in other countries, the overall relationship remains; higher oil contents result in lower safe moisture levels for storage.
Also, in recent years, there has been more interest in bagged storage for all crops. Recent work conducted by various cooperators in Saskatchewan and funded by SaskCanola indicated that bag storage, even of higher moisture canola is possible, but that longer term storage still requires regular monitoring. ( http://www.saskcanola.com/research/report-b o y l e-highmoisture. html ) . Higher moisture, especially when combined with higher ambient temperatures during combining still make for a highly unstable product. Birds such as ravens and other wildlife such as deer, moose and elk can make holes in the bags and cause spoilage and other storage losses. Just because you can put the product in an air-tight bag, that doesn t mean that it s immune to spoilage!
TIPS FOR SAFE CANOLA STORAGE
All these characteristics can make canola more tricky to store than most cereals, so in summary, the following storage tips are recommended:
1. Use suitable aeration and monitoring equipment. Size aeration fan and screens appropriately to the size, diameter and height of grain in the bin. Install temperature monitoring cables in all bins destined for canola storage so that regular monitoring is more accurate, convenient and practical. Alternately, if aeration equipment is not available, be prepared to turn the grain in the bins by removing over half of the bin contents and augering it back in. This helps to break up any convection currents that may have occurred in the bin.
2. Use smaller bins whenever possible and practical. Smaller bins will generally suffer less moisture migration from convection than larger bins and therefore be less prone to resultant heating. Also, if remedial action is required, it is much easier to rotate the grain in a smaller bin than a larger one.
3. Monitor stored canola regularly no matter what type of storage is used (bin, bag, quonset or pile) and be prepared to take action if necessary.
4. Lower grades and more foreign material make the stored canola more unstable. Plan on moving these compromised products sooner if possible.
5. Higher oil contents require lower temperatures and/or moisture contents for safe storage.
Keep in mind that your economic returns and profits don t materialize until the resulting crop is delivered and sold. Don t sit back and assume that just because the crop is in the bin that it s safe and that the race is over. Far too often, profits are lost because grain has deteriorated or spoiled in storage. Therefore, plan on using the necessary equipment to monitor your stored crop regularly and be prepared to cool or dry it as necessary to store it successfully until the grain can be delivered and marketed.
JohnMaykoisasenioragri-coachwith Agri-TrendAgrologyandoffersagri-coaching servicesintheMundare,Alta.,areawherehe alsofarmswithhisfamily