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Senior Contributor

Air drying corn

I recorded some temps and relative humidity readings. I burn wood in a old discarded home wood burning stove to heat the air. Just wandering if anyone can tell without much calculation if it's worth my time.
Temperatures: 68 outside
75 at the fan
62 at the bin vents
Humidity: 74% outside
58% at the fan
85% at the bin vents
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10 Replies
Senior Contributor

Re: Air drying corn

I see you have not received any replies so I will wade in.

 

I think your theory of raising the air temp is the way to speed up drying whether it is worth the time or not I go not know.

Is the wood available or do you have to gather and cut and split it? if so I expect buying fuel would be a cheaper form of energy but what else do you do with your time? do you have other more productive and income producing things to do?

These all seem like factors to consider.

 

As for air drying corn I have done that for years with nothing but air and a big fan, lots of air.

I usually wait for later in fall to bin it and so it is dryer and cold temperatures are a help since the options are to dry or cool the corn in a short time.

Cool corn will keep longer and then can be dryed as the conditions allow in later days with less humidity.

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Senior Contributor

Re: Air drying corn

I cut my own timber. I give away several cords a year just to clean up the tops. But it does take some time. The time I spend keeping the fires going durring harvest seems the most inconvenient. I started out just air drying, but got caught with wetter than I thought corn in the bin a few years ago. Then it rained every other day and stayed warm for about three weeks. That was when I initially set up my "system".
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Senior Contributor

Re: Air drying corn

Sorry it took so long to reply, but I have been air drying for as long as I've been farming, FWIW.

 

I do have heaters for the fans, but I only run them if I have to get the corn dry in a hurry, like when I am running out of drying space, and need to get it dry enough to move to a storage bin.   I have dried corn down from 20%+, using nothing but air.

While I haven't done any truly scientific study of it, I have two rules of thumb, that I follow, that seem to dry the corn down the fastest, or at least with the least amount of fan use.

First would be the obvious warm, sunny, dry days.  
Not so obvious, would be the days when we get a frost or freeze overnight.   It seems that when the air temperature drops below freezing, a lot of moisture drops out of it.   Pushing the dry air through corn that is well above freezing, really seems to pull the moisture out.   With no heat, I have had times when water was dripping off the roof in the morning.   As the day warms, it seems to re-warm the corn, ready to do it again the next night.

The single biggest thing that helps me, when I try to dry corn when the moisture is above 18 or so, is a stirring mechanism in the bin.   It breaks up any lumps or crust, ensuring even airflow through the bin.   Some think the only time you need to stir corn, is when using heat, to pull the dry corn off the bottom, to get the wet corn to the heat, so that you don't wind up with the bottom corn down to 12%, before the top gets dry.   I think that it is equally important, to break up any lumps of fines or trash, so air flows through those areas of the bin, rather than around them.   A Stirway will also break up any crust that may form, as well.

 

Oh, and to your conditions, IMO, if you have 55% moisture going in the bin, and 85% coming out, you have to be pulling water out of the corn.   How fast it dries, has a lot to do with how much ariflow you have through it.   I have a small 3K bushel drying bin, with a 10HP fan, and a liquid-to-vapor propane burner, and I can easily dry a binful of corn down from 20% to 15% overnight, if I want to use heat, and 3-4 days using only air.   I have the same fan and burner on a 10K drying bin, and it takes maybe 4 days to dry the corn from the same moisture with heat, and maybe 2 weeks using only air.   The difference is airflow, the small bin, is shorter, so the fan has a shallower pile to push the air through, so the air exchanges at a faster rate.  Also, the air tends to pull most of the moisture from the bottom part of the pile before it gets saturated with moisture, so only the bottom portion of a deeper grain column dries fast.   After that, the dry line of the corn tends to slowly move upwards.   Stirring doesn't really get it to dry faster when only using air, but it leads to a more uniform moisture throughout the bin.

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Senior Contributor

Re: Air drying corn

I regret not getting stir augers. Probably will on next bin.
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Senior Contributor

Re: Air drying corn

I would not even consider putting up a drying bin, without them.   I would rather go without a heater, than a stirway.

They break up any areas of limited airflow, level the corn in the bin, break up any crust, and when coupled with air-ways, will prevent corn from sticking to the bin sidewall, as well.  The ONLY reason I can think of not to have one, is cost.  You not only need to pay for the stirway, you need to get a bigger bin for the capacity, as you lose probably 2 feet of grain depth in the bin.

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Senior Contributor

Re: Air drying corn

I rent a small bin that has stir augers. The bin has no electric so I dry and cool the corn at home. Then just run generator to get some fresh air through it every now and then. This year I needed the extra space so I filled it all the way to the peek. Do you think I could damage anything doing this.
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Senior Contributor

Re: Air drying corn

Is the corn wet, or dry?

If it is wet, it can pull the stirway off where it anchors to the roof, or buckle the roof in a worst case scanario.

Usually if the corn is dry, it flows well enough, it won't to a lot of damage, other than maybe pull a wire loose.  The longer it sits under the corn, the wetter the corn, and the deeper the corn over the top of it, the more I'd worry.

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Senior Contributor

Re: Air drying corn

It's dry. I thought it should be ok but wasn't sure. just thought I'd try it and see what happens.
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Senior Contributor

Re: Air drying corn

I'd unload a little, then stop, climb the roof, and look to see if anything looks like it is flexing, stretching, or pulling loose.  If it is starting to bow the roof, you can grain vac the corn off the top of it through a manhole.

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