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Canola Storage Considerations in November

21 November 2012
Alberta Agriculture, Food and Rural Development

CANADA - An Alberta Agriculture specialist says that November is a good time to ensure canola is stable going into winter.

“The open fall experienced in most areas of Alberta gave us better initial grain storage conditions compared with most years,” says Neil Whatley, crop specialist, Alberta Agriculture and Rural Development, Stettler.

“However, continued diligence about potential grain storage problems is necessary as winter approaches, especially with canola due to the rapidity with which damage can occur. Due to its high oil content, canola seed is more susceptible to deterioration in storage than cereal grains.

"As such, canola is stored at a lower seed moisture level to prevent spoilage. Safe, long-term canola storage is at or below eight per cent moisture content and cooler than 150 Celsius. However, cooling outside air temperatures need to be properly dealt with to ensure safe storage.”

Canola respires or goes through a ‘sweat’ period for up to six weeks after being binned. Because of this ‘sweat period,’ canola should continue to be monitored, even if it is initially binned dry. Respiring canola generates additional heat and moisture, creating an unstable condition. This instability can potentially result in hot spots or mould growth and, when mould begins to form, creates more heat that accelerates the spread of mould growth. As such, aerating stored canola during respiration is important. Spoilage can be eliminated if the canola is sufficiently conditioned to the point where the aeration cooling front moves entirely through to the top of the grain mass.

Changing outside air temperatures in the spring and fall cause repeated moisture cycles in a bin, permitting moisture to concentrate in certain bin areas. This can potentially lead to spoilage and heating.

“As outside air temperatures decline during October and November, the grain nearest to the outside bin edges cools first,” says Neil.

“This cooling system migrates downward along the bin edge, then upward through the central core. As this cooling system migrates, it gathers moisture and warmth that create a pocket of humid and warmer air at the top of the central grain core where spoilage and heating can begin. So, as outside air temperatures decline, aeration fans should be operated again until canola at the top of the bin is cooled to the average daily temperature.

"Due to continuously declining outside air temperatures, it is wise to aerate repeatedly until the whole canola bin is between 0 and 50 C. Therefore, November is an important month to check canola bins again to realise if they are stable going into winter as temperatures drop below 00 C and stay there. Attention should be given to any area of the bulk that is not cooling at this time of the year because spoilage could begin there.”

Producers may also consider turning one third of the canola bulk out of a full bin by truck in November. “This would be the method used if aeration is not possible, but may be an important task to complete in November even if aeration is used,” notes Whatley. “Moving the grain disrupts the moisture cycle created by declining outside temperatures, cooling the grain mass and reducing the risk of spoilage. Even if bin temperature is being monitored with sensors, this may not provide a complete reading of the whole bin as problems may emerge in pockets away from the sensors. So, turning the grain ensures cooling as well as allowing producers to be able smell the grain as they are moving it to realize if any grain is in the first stages of spoilage.”

Extra caution is required in unique circumstances. “Canola that was stored with a higher green seed count this fall has a higher moisture content than your average mature canola seed, potentially increasing spoilage risk,” explains Neil. “Such canola should be delivered as soon as possible to prevent spoilage, which could result in further price reduction. Extra diligence is also required when canola is stored in large bins, especially tall and narrow bin types that can reduce aeration air flow due to increased compaction.”

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