Source: Government of Alberta
“Stored crops are important to monitor,” says Neil Blue, provincial crops market analyst with the Alberta government. “Several cases of spoiling crops have showed up lately, leading to marketing difficulty and large price discounts. Perhaps the mostly warm temperatures this winter and the January period of record cold temperatures have been a factor.”
After being placed into storage, grain and oilseeds will respire for a month or more, and this respiration can release moisture, which in turn can lead to spoilage. Dense crops like canola are particularly subject to storage problems, although all crops with moisture can spoil.
Alberta had a very dry harvest with most of the crop combined at officially dry moisture levels. However, some of the harvest days were quite warm, and those warm crops placed into storage have a large temperature differential compared to winter temperatures.
As the outside air becomes cold, the temperature of the outside of the crop mass in the bin cools first. This causes a temperature and moisture migration down the bin walls and then into the bottom centre of the grain mass. The air then moves up through the centre of the bin, picking up moisture along the way. As the warmer moisture laden air encounters cooler grain near the top of the crop mass, heating can begin. That is why spoilage tends to occur near the top of the bin during the winter.
Canola harvested with green canola or cereal seeds, or green plant material increases the risk of spoilage. Although canola for marketing purposes is considered dry at 10% moisture, safe longer-term storage moisture levels are below 8%. If it is binned at high temperatures, canola can even spoil at 6% moisture.
Aerating crops during the respiration period will reduce or eliminate the chance of spoilage. Another recommendation is to ‘turn’ the stored crop by removing some from each bin, let it sit on a truck for a day or more, then return it to the bin. A suggested time to do this is when the outside temperatures are cold.
“Aerating and turning will help to even out the temperature of the stored crop and break up the natural temperature and moisture flow within the bin,” explains Blue. “Many producers also use in-bin monitoring systems to detect potential storage trouble. While lower than last crop year’s prices, crop prices are still historically high, and worth protecting in storage.”
