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Tool figures corn drying, shrink

The near-ideal growing conditions in late summer and fall benefited Iowa’s corn and soybean yields, as well as crop quality. However, the crops are maturing later than normal. This leaves much of Iowa’s corn harvest to stretch from October well into November. Harvest is a week or two late getting started, and higher corn moisture levels are adding to shrink losses and drying costs.

Tool figures corn drying, shrink

The near-ideal growing conditions in late summer and fall benefited Iowa’s corn and soybean yields, as well as crop quality. However, the crops are maturing later than normal. This leaves much of Iowa’s corn harvest to stretch from October well into November. Harvest is a week or two late getting started, and higher corn moisture levels are adding to shrink losses and drying costs.

Rather than take discounts for delivery of corn above 15% moisture, many farmers will let their crop dry down naturally in the field before harvesting. Iowa State University studies indicate unharvested corn could dry at a rate of 0.3 point of moisture per day in wet, cool weather during the fall. Drydown improves to 1 point of moisture per day in hot, dry weather. This in-field drying cuts the cost of artificially drying the crop, but it may delay harvest and result in more stalk lodging and ear loss.

Cash flow constraints and lack of adequate on-farm storage are two reasons why some farmers may choose to deliver corn at harvest above 15% moisture content. Lack of adequate on-farm and commercial drying capacity are other possible reasons for making cash sales. Farmers may choose to deliver corn above 15% moisture, accepting a discounted price but avoiding additional shrink losses, as well as drying costs. Commercial storage requires the corn be adjusted to 14% moisture to be placed under warehouse receipt.

The farmer making cash corn sales could still choose to use a minimum-price contract to improve the final settlement price. This likely anticipates a futures price rally in the deferred contracts, likely May or July 2015 corn futures.

Sell at harvest, or dry and store?

ISU has a new online decision tool that compares selling corn at harvest versus the shrink loss, drying, and storage costs from drying and storing corn. Using this ISU Extension Ag Decision Maker decision tool “Corn Drying and Shrink Comparison,” File A2-32, you can plug in your own information. Here’s how it works:

Step 1. Variable-cost estimate for on-farm drying. Choose a drying system and input your variable costs. Those are propane, electricity, drying time labor, drying capacity, average points of moisture removed per bushel, total bushels per year and total investment in drying system.

Step 2. Yield and moisture projections for unharvested corn. Input your own decisions regarding acres harvested, wet gross bushels of yield, corn moisture in field, days before harvesting and expected cash grain price at harvest.

Step 3. Compare your grain sale alternatives at harvest. You can sell wet corn and incur a moisture discount; dry the grain commercially and then sell; or dry it on-farm and sell it.

Step 4. Input your moisture, drying and shrink information. This includes final moisture level for commercial sale, moisture discount for wet corn sale, commercial drying charge and shrink factor. You might want to consider additional on-farm costs for drying and hauling.

Step 5. Input your sales alternatives for after storage. This includes the number of months that grain will be stored, cash price paid after storage, moisture level for storage, minimum charge for commercial storage, base rate in months, monthly minimum charge for commercial storage after minimum, quality deterioration on-farm storage, fans, electricity and labor on-farm storage and short-term interest rates.

Available on ISU’s AgDM website, the decision tool uses assumptions and compares net revenue after storage costs and the breakeven selling price needed to pay storage costs. This one and two other new information files (pdfs) and decision tools (spreadsheets) were developed by retired ISU economics professor William Edwards and are posted at the ISU Extension Ag Decision Maker at They are:

“Estimating the Cost for Drying Corn,” File A2-31

“Corn Drying and Shrink Comparison,” File A2-32

“Cost of Storing Grain,” File A2-33

Considerations when using these tools are wet grain at harvest resulting in higher shrink losses and drying costs; concerns for adequate on-farm and commercial drying and storage capacity; and moisture discounts if selling corn at harvest.

Johnson is the ISU Extension farm management specialist in central Iowa.

Making room for new crop corn

Should you send some corn to the elevator or grain processor early? Some farmers are using that strategy this fall. Big crops and a tight storage will mean a heavy flow to grain elevators in the later-harvest season once the on-farm bins are full. Grain buyers in September were encouraging farmers to send some grain to elevators and processors early in the season and to continue with this plan through harvest.

Elevators will have to fill piles covered with tarps and other less-flexible storage options this year. Allowing elevators to start filing their bins early will even the flow of grain coming into elevators and reduce the risk of having to put wetter corn in outdoor storage locations.

Instead of selling 2014 corn, if you have 2013 crop corn in the bin, it’s best to move the old crop out, says Charles Hurburgh, director of the Iowa Grain Quality Initiative at ISU. “Don’t mix 2014 corn with 2013 corn. The 2013 crop has poor storage properties. Sell the corn carried over from last year’s harvest and replace with 2014 corn. Granted, rotating stocks creates logistical issues when done during harvest. But you’re better off moving old-crop corn, and drying and storing the new crop.”

Higher quality this fall

Corn harvested this fall is of higher quality. Moderate temperatures and adequate soil moisture during grain fill created well-filled kernels with generally high test weights (57 pounds per bushel or higher). High test weight means above-average storage properties. This is good because a considerable amount of 2014 corn is going to have to carry over into 2016, notes Hurburgh.

The lateness of the 2014 growing season ensured above-average grain moisture at harvest. Average grain moisture for Iowa corn is about 17% to 18% at harvest. Delaying maturity takes away several drydown days. Most corn this fall will likely have a moisture content of 20% or more as the grain comes out of the field, unless October is very warm.

If you have high test weights, Hurburgh advises using more bin cooling or dryeration this fall, stopping it at a percent or so higher moisture content than normal. This will increase grain dryer capacity, as long as storage bins have adequate aeration (aerating at 0.1 cubic foot per minute per bushel, or greater). Identify the highest test weight fields or corn hybrids, and place that corn in the long-term storage bins.

Exceptions are corn with leaf blight, storm damage or frost damage, which will need to be harvested quickly to avoid ear loss. This corn will be on the lower end for test weight and storability. If weather is wet and cool, scout for field mold as buyers will be looking primarily for vomitoxin in these cases.

Grain management tips

If corn can dry down in the field, there may be a little leeway in storage time or shelf life of the stored crop. But the steps to take for managing grain are the same as always, says Hurburgh:

Uniform drying and cooling of grain in bins is goal. Using adequate aeration (0.1 plus cfm/bu.) is a must.

A cooling cycle should be completed with every 10 to 15 degree change of outside air temperature vs. grain temperature.

Cool down stored grain to below 40 degrees F quickly after drying.

Remove the center core of fines immediately from the center of the bin.

Regular inspection of stored grain, and temperature monitoring, is a must.

Monitoring grain and watching for temperature changes is important (a 3 degree increase in two weeks without aeration being run, is significant).

Stay within “temperature-moisture” guidelines for storage.

ISU Extension has several 20-minute training modules covering aeration and dry grain storage, fan performance, and dryeration. Visit and select “Grain storage training.”


COMPARE COSTS: A new decision tool available on ISU’s Ag Decision Maker website compares selling corn at harvest versus shrink loss, drying and storage costs you would incur by storing the corn.

This article published in the October, 2014 edition of WALLACES FARMER.

All rights reserved. Copyright Farm Progress Cos. 2014.

Harvest Management

Crop Drying

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