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Wet Corn: Storage and Late Harvest Options

BROOKINGS, S.D. - Due to uncooperative weather conditions in areas of the state, harvest 2018 saw many South Dakota farmers facing a difficult decision - harvest wet grain or let it stand in the field.

Whatever their final decision, SDSU Extension Agronomy Field Specialist Sara Bauder provides advice and options to farmers.

“Farmers still have grain storage options that can help maintain quality over the winter as long as bins are checked regularly, and precautions are taken to avoid spoilage as spring temperatures draw closer,” Bauder said.

Corn still in fields

This time of year, there typically is not any significant field drying that will occur in corn (Table 1), Bauder said. “Most farmers are well aware of the risks that come with leaving corn standing over the winter, hoping corn stalks and cob shanks withstand winter winds and snows, so that a dryer harvest can occur in the spring.”

Losses from leaving corn standing over the winter vary greatly. Bauder explained that it depends upon many factors; like variety selection, field management and weather.

“When making late harvest decisions, it is important to take the economic comparison of storing and drying high moisture corn versus field losses and damage to wet soils into consideration,” she said.

She said farmers should also consider the following:

  1. PET: Potential Evapotranspiration (based on factors similar to those that affect drying)
  2. EMC: Equilibrium Moisture Content (indication of expected corn moisture content to which corn will dry in the field)

“If snow melts and soils allow, some farmers may opt to harvest yet this winter,” Bauder said.

When harvesting during winter, Bauder said farmers need to consider estimating the cost of propane if high heat drying is in the plans. She quotes Kenneth Hellevang with North Dakota State University, “To estimate the propane cost of drying per bushel per point of moisture removed, multiply the propane price per gallon by 0.02. For example, the cost to remove 10 points of moisture using $1.50 propane is $0.30 per bushel. Dividing the propane cost by the corn price provides the percentage of corn losses that will equal the drying cost ($0.30 divided by $3.50 equals 9%). Also, verify the impact on insurance of leaving the corn in the field.”

There are a few exceptions to this rule however, including:

  • Newer dryers with saturators and vacuum cooling might improve efficiencies.
  • Wet points’ do tend to come off easier than the dry points. For example, 14 percent moisture is harder to reach from 19 percent and will take more energy on average than drying corn from 25 to 20 percent. 

Monitor bin temperature weekly & other considerations for wet corn in storage
Although there are still fields in the southern part of the state with corn still standing, Bauder said there is also a good chance that there are several bins storing relatively wet corn.

With high moisture corn, Bauder said bin temperature is extremely important and should be monitored in various parts of the bin on a weekly basis at minimum.

To monitor, probe in several areas of the bin using a grain thermometer. “Allow the thermometer several minutes to equalize before moving to the next site,” Bauder said.

If heating in grain is detected, or there is more than a 5 to 8-degree difference in temperature between any two areas in the bin, it is recommended to run the aeration fan immediately.

Bauder reminds readers that the goal of binning high moisture corn is to freeze the corn over the winter, keeping the temperature between 20 to 30 degrees Fahrenheit.

Below she outlines some best management practices:

  1. Holding very high moisture corn (22-24 percent) is possible in the bin, but extreme care should be taken to avoid spoilage. Monitoring temperature and keeping it near 20 degrees Fahrenheit throughout the bin is key.
    Grain at this high moisture level will likely need to be ran through a high temperature dryer by early March when temperatures begin to rise.
    On average, the south bin wall receives more than twice as much daily total solar energy heating in February than it does in June, making temperature monitoring imperative.
  2. Corn from 19-21 percent moisture allows the operator to choose between high heat drying or natural air drying if the proper equipment is available. As spring approaches, grain should be monitored, and a drying decision should be made. When using natural air drying, it is extremely important that access to the proper fan size is available, or suitable drying will not occur. For assistance determining required airflow rate and fan size necessary for a bin see the University of Minnesota fan selection program at this link: https://bbefans.cfans.umn.edu/.

Other Tips

When using fans to cool grain or maintain temperatures in the winter, care should be taken to avoid bringing moisture back into the bin.

Turning fans off and keeping them covered during periods of precipitation or fog can help ensure quality of grain.

In addition, leaving extra air space in bins and leveling off grain can also help ensure that grain is frozen evenly throughout the bin.

To test corn moisture, allow grain to warm up to at least 40 degrees Fahrenheit for an accurate moisture meter reading.

For further information, contact Sara Bauder, SDSU Extension Agronomy Field Specialist.

Table 1. Estimated Corn Field Drying based upon NDSU data.

  EMC (%) PET (in) Est. Drying (%pt)
      Month Week
Sep 15 4.0-5.0 18 4.5
Oct 16 2.8-3.5 11-12 2.5
Nov 19 0.8-1.2 4-5 1
Dec 20 0.5-0.8 2 0.5
Jan 21 0.5-0.8 2 0.5
Feb 21 0.5-0.9 3 0.8
Mar 19 1.3-1.6 5 1
Apr 16 3.2-4.5 16 4
May 14 6.5-8.5 30 7

PET: Potential Evapotranspiration (based on factors similar to those that affect drying)
EMC: Equilibrium Moisture Content (indication of expected corn moisture content to which corn will dry in the field)
Source: K. Hellevang, NDSU.

 

A snow-dusted corn stand.
Some corn has been left in the fields due to the uncooperative weather conditions.
A grain storage bin.
Bin temperature should be monitored and maintained throughout the whole bin.