Here are some features of a good canola storage bin…
Fan size. A bin of canola generates a high static pressure (or resistance to airflow) which results in a lower airflow rate from the fan. For conditioning (cooling), you need 0.1 to 0.2 cfm/bu of airflow. If adding supplemental heat to dry canola, airflow of at least 0.75 cubic feet per minute per bushel is recommended. If fan size is insufficient for the job, fill the bins part way to improve airflow.
More on this from Joy Agnew, stored grain researcher with Prairie Agricultural Machinery Institute: “One question I get all the time is if a fan is sized to allow natural-air drying (NAD) for canola, if that same fan and bin are used to store another crop, will the fan be oversized? The answer is yes. You will have a much higher airflow rate with other crops if the fan is sized for canola. The next question: Is that a bad thing? It might be. First off, anything above 2.5 cfm/bu airflow rate is likely not increasing your drying capacity or drying rate. So you are paying a higher power bill for no added benefit. Secondly, very high airflow rates (above 2 cfm/bu) may result in overdrying and cracking of certain crops (such as pulses) due to the high drying rate. So high airflow rates may be detrimental for some crops. Some producers prefer to size fans for NAD of wheat and if they need to use that bin/fan for canola, they only fill the bin partway to help achieve a sufficient airflow rate. This does work, but there is an increased chance of moisture accumulating in the headspace of the bin. If a bin is only half full, there is a lot of headspace to cause problems. If they want to go this route, they may want to consider an active ventilation system (a fan at the outlet(s)) to help pull moist air out of the headspace.”
Bin size. Cooling will take longer in bigger bins because there is less surface area relative to the volume. Natural cooling (without aeration) may not happen at all in the core.
Holes. Bins with holes at the bottom (from worn seals, gaps in concrete, cracks in welds, rust or whatever) will lose a lot of airflow through these holes – as air will take the path of least resistance. These bins will need to be patched or replaced or filled with something other than canola.
Bonus reminder: Check your moisture meter. If you’re relying on moisture meter readings to determine canola storage risk, make sure the meter is accurate. Moisture meters can lose accuracy. Calibrate it often and occasionally get a test at a delivery point to see how it compares to your on-farm reading.