Condition all canola immediately after combining to cool it down, even out the temperature throughout the bin and remove any moisture. Even “dry” canola can release moisture through natural seed respiration that occurs in the first hours to weeks after harvest.
Risk factors
Moisture
The ideal canola seed moisture for safe long-term storage is eight per cent. Consider moisture and temperature together. For example, eight per cent moisture is still too high if the grain temperature is 25°C or more. Ten per cent moisture is probably low enough for safe storage as long as grain temperature is 5°C degrees or less.
Moisture creates a more hospitable environment for moulds that trigger heating. Clumping is a sign of mould growth. This can occur fairly quickly. Lab-based research found that canola seeds at 25°C and 10.6 per cent moisture clumped together after 11 days and visible mould colonies appeared after 21 days. With variable conditions in most bins, clumping may occur more quickly in an on-farm situation. Read Questions about handling high-moisture canola.
Hot canola
Canola binned hot, even if it has low moisture, low dockage and low green, should be put on aeration to cool it down. This will even out the temperature throughout the bin, and help remove moisture from respiring seed. Even at low moisture, air movement inside the bin could concentrate this moisture. Try to get canola down to below 15°C at harvest time, then turn fans on again in the early winter to reduce temperature to at or below 0°C.
Green canola
Green canola seeds can increase the storage risk, even if canola is dry and cool. Monitor closely. Small shriveled canola seed, which often comes with high green seed, can mean smaller air pockets between seeds in the bin. Smaller particles will increase the resistance to air flow. This makes it even more important to leave the fan on as it will need to work longer to cool the entire bulk.
Dockage
–WEED SEEDS
Weed seeds tend to contain more moisture than canola seeds, especially if they are green or immature. If they congregate in pockets in the bin, weed seeds can create a localized hot spot for spoilage to begin. Bits of green plant material in the sample similarly increase the risk.
–CHAFF
Without a spreader in the bin, larger chaff tends to concentrate closer to the walls of the bin and fines closer to the centre. This distribution exaggerates airflow problems, with more air taking the path of least resistance up along the walls of the bin and with less air pushing through the central core. Chaff can also have higher moisture than seed, adding to the risk.
The Canadian Grain Commission compared canola seed moisture and dockage moisture for 49 samples collected through its Harvest Sample Program in 2023 and another 50 in 2024. Average seed moisture for 2023 samples was 7.46 per cent, which is perfect for safe long-term storage of canola. Average dockage moisture was 10.8 per cent. The 2024 results, shared in the table below, are similar. If that dockage clumps together, as it often does, this could present a storage risk. Straight-combined canola could have an elevated chaff risk if the sample contains higher-moisture stalk and pod material.
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