New research results could forever change how we approach natural air grain drying. It’s amazing that we’ve been doing it so wrong for so long.
What conditions give the best drying when an aeration fan is running on a grain bin? The assumption has always been that a hot, sunny day with low relative humidity is best. Turns out it’s not that simple.
A fan typically removes a lot of moisture during the first day of storage, no matter the outside air temperature. After that, it’s much better to have the fan running during cool nights than warm days.
This counterintuitive approach stems from work done by former University of Regina professor Ron Palmer using data compiled by the Indian Head Agricultural Research Foundation.
Since it’s difficult to know exactly what’s happening inside the grain bin, Palmer concentrated on measuring the moisture in the air entering the bin as compared to the moisture in the air exiting the bin. That way, he could tell when there was drying and when moisture was being added back into the grain.
Temperature is a huge determining factor in how much moisture that air can hold. The relative humidity is simply how much moisture is in the air, relative to how much it could hold at a particular temperature. Overall, cold air is dry air.
Palmer found that fans were actually putting water back into the grain during the hottest days. The warm air carried lots of moisture and released it when it hit the cooler grain. At night, when the incoming air was cooler, there was both cooling and drying of the grain.
Relative humidity matters, but it’s not nearly as important as the temperature. Palmer’s work shows that temperature is a great guide for knowing when the fan should be on and when it should be off.
If the temperature of the air going into the bin is higher than the temperature of the air coming out, turn the fan off. You’re heating up the grain and you’re actually adding moisture.
If the temperature of the air going in is lower than the temperature of the air exiting, you’re cooling and drying the grain. Keep the fan running.
The temperature of the air coming out of the bin will be roughly the same as the temperature of the grain near the top.
The recommendation has always been to start the fan and let it run continuously. Palmer’s work indicates that we can run the fan half the time and the grain will end up cooler and safer. Meanwhile, we’ll only use half the electricity.
He points out that there’s no rush to dry grain. The rush is to cool it before spoilage can occur and the colder the better.
Palmer said farmers who aren’t entirely convinced and still insist on running their fans continuously should at least shut them off for the last time in the morning when the grain is as cool as it can be.
I put a propane heater on one of my aeration fans a couple years ago. Now, I’m wondering if I’ll ever use it. Palmer believes supplemental heat is not required and can actually increase the risk of spoilage.
It’s radical new thinking, but it’s extremely logical.
The research foundation is planning more research to validate and fine tune the findings. It’ll be interesting to see the reaction from other research institutions.