How to condition canola with natural air drying and supplemental heat

Due to its high oil content, canola has a higher risk of spoilage compared with numerous other crops. If it’s too wet or too warm inside the bin, moulds, mites and insects will thrive, leading to spoilage and lost revenue for farmers.

Charley Sprenger, a research project lead at Prairie Agricultural Machinery Institute (PAMI) in Portage la Prairie, Man., offered some tips on how to prevent canola spoilage during Canola Week 2021 last December.

The best conditions for long-term storage of canola are eight per cent moisture and temperatures less than 15 C, Sprenger said. Dry and cool canola can be stored safely longer, so “it’s really key that both temperature and moisture be monitored and controlled to prevent spoilage, and the larger the volume of stored grain, the higher the risk.”

One of the ways to control moisture levels inside the bin is through natural air drying with aeration fans, which Sprenger said works well as long as there is sufficient airflow and the ambient air has the capacity to dry. Warmer air is generally better at drying grain, and airflow is important because this is what moves moisture out of the grain mass.

“The temperature is really what removes the moisture from the canola and the airflow rate is what removes the moisture from the bin, so we want to make sure these are balanced,” said Sprenger.

Adding supplemental heat to a natural air drying system can be an efficient and effective way to dry stored grain, if done correctly. “Sometimes the ambient conditions just aren’t favourable for natural air drying, but we can add heat to an in-bin system to improve this capacity to dry.”

Farmers can find helpful information from PAMI on grain drying and storage at pami.ca/publications, including the following seven tips for using supplemental heat with natural air drying.

1. Use a proper heater

Only use a heater that is certified by the Canadian Safety Association designed for use with grain storage fans. Make sure to follow the manufacturer’s instructions for installation and operation.

2. Ensure adequate air flow

When using supplemental heat with natural air drying to dry grain, the airflow rate must be at least 0.75 cubic feet per minute per bushel or there is a risk of overheating the grain. Low airflow rates also won’t be as effective at removing moisture from the bin. PAMI has some guidelines for measuring airflow rates.

3. Don’t overheat grain

Do not exceed an inlet (after heater) temperature of 30 C during drying as this increases the risk of grain overheating. Airflow rates of 0.75 to one cubic feet per minute per bushel can keep up with moderate drying rates, but not with high drying rates associated with high temperatures above 30 C.

4. Limit air temperature increases to 15C or less

Higher temperatures inside the bins will reduce heat transfer efficiency within the pile and can cause the grain to overheat. They also increase the chances of the canola freezing and sticking to the inside walls of the bin.

5. Maintain consistent air temperature

When possible, try to maintain a consistent air temperature inside the bin during drying. Thermostatic controllers will help with this and can also minimize day-to-night variations in temperature inside the bin.

6. Be cautious when it’s cold

If you’re using higher temperature settings of supplemental heat when it’s very cold outside, this can lead to condensation and grain to freeze along the inside walls of the bin. This can be avoided by limiting temperatures and reducing the drying rate of natural air drying and supplemental heat when it’s frigid outdoors.

7. Monitor grain condition

Monitor grain condition during drying by using in-bin cables and/or taking samples. This reduces the risk of overheating and will indicate when the canola is dry.

– Mark Halsall is an associate editor with Grainews.