Corn under 20% Moisture - Now What?

After a hot, dry summer here we are in mid-October with corn coming off the field at 20% or less moisture content. Everybody should be ecstatic but rather there are farmers wondering what to do with this unexpectedly dry corn. The bottom line is that it really depends on what the corn will be used for.

There are combines now harvesting corn for a number of reasons.

1. Need corn for feed.
2. It's October
3. Corn is starting to go down
4. Beans are done
5. High moisture silo needs filling

Field Dry Down Rate

Typically corn loses 1 - 2% moisture content per week when corn is less than 20% M. C. standing in the field. As temperatures drop and moist air persists this dry down rate slows. With mature corn and hot dry weather last week moisture levels dropped significantly which may cause people filling high moisture silos concern.

Corn Use Plan

Corn that is destined for use on the farm can be treated differently than corn that you plan to market off-farm. Corn is sold commercially on a dry basis of 15.5% moisture content. If you plan to market corn off the farm, the corn needs to be 15.5% moisture content with drying charges imposed for moisture levels above this level. You either have to dry your corn to 15.5% M. C. or accept the associated drying charges for wetter corn. With shrewd or creative marketing you may find a buyer that can use corn that is higher than 15.5% M. C.

Allowable Storage Time

As the cooler fall temperatures arrive, keeping corn becomes somewhat easier. In other words, the colder the grain is the longer it can be kept without losing appreciable dry matter. The following storage times are based on corn temperatures not outside air temperatures. Corn at 18% moisture will keep around 90 days at 10oC and longer than 90 days at 5oC. Corn at 22% moisture will keep just shy of 30 days at 10oC and about 60 days at 5oC. The weather will get colder as the weeks go by and if you keep corn in good condition you have some time to do something.

Leave it in the Field

With nice weather, corn in the field will continue to dry down. The reality is that more stalk breakage is apt to occur as the winds of November blow. The fields may get wetter which will result in damage from tire tracks in the field. An early snow would suspend harvest with more stalk damage likely as a result of the additional weight on the crop.

Field to Bin

Farmers' calls tell us that corn is coming off under 20% and as low as 17% moisture content. From the allowable storage time charts we know corn at these moisture levels will keep for 45 days or more, depending on grain temperature. You can keep corn 18% M. C. and less with timely aeration and sound storage management practices. You need clean corn free of fines and foreign material, which can cause spoilage problems. With normal aeration rates of 1/10th to ½ CFM per bushel all you can do in the bin is manage temperature. To change moisture of stored grain you need greater than ½ CFM per bushel and preferably 0.75 to 1.0 CFM / bu.

If the corn is being fed to livestock the 18% corn really just has to be kept. Drying it down to 15.5% is not necessary unless the storage bins lack good aeration capability.

Field to Drier

If your plan involves selling the corn "dry" at 15.5% moisture content it has to be dried. The limiting factor in drying this low moisture corn will be the throughput capacity of your column drier and associated conveying systems. You will be able to remove moisture quicker than you can move corn through the drier. Reducing your drying temperature should help get the job done efficiently. Once through the drier you can manage the corn as you would otherwise.

With roof top driers or other bin driers, reducing drying temperature may not be as necessary. By using the temperature sensors to determine corn moisture, one or two batches should get you to your desired moisture levels.

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