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Producers Need Estimate of Corn Drying Costs

An NDSU Extension Service agricultural engineer offers corn drying advice.

Producers should have an idea how much drying their corn will cost when they make drying and marketing decisions.

Ken Hellevang, North Dakota State University Extension Service agricultural engineer, provides the following drying cost estimates and advice to assist producers in making those decisions:

  • The cost to naturally air-dry corn from 21 percent to 16 percent is about 11 cents per bushel. That’s based on normal climatic conditions in North Dakota, an electric rate of 7 cents per kilowatt-hour (kwh), an airflow rate of 1.25 cubic feet per minute per bushel (cfm/bu), and drying that starts by the middle of October and finishes in early December.
  • To dry to about 13.5 percent moisture content requires supplemental heat to warm the air about 3 to 5 degrees. This increases the drying cost to about 15 cents per bushel using off-peak electricity at 4 cents per kwh and 19 cents per bushel using propane at $1.40 per gallon. Drying time is reduced slightly due to adding the supplemental heat, with completion expected about Nov. 23.
  • Since the rate of drying is related to the airflow rate, to naturally air-dry corn using an airflow rate of 1 cfm/bu instead of 1.25 cfm/bu extends the finishing date past the middle of December. It also increases the final moisture content to more than 17 percent. The drying cost still is about 11 cents per bushel, but the final corn moisture content is wetter.
  • Natural air-drying will dry 21 percent moisture corn to only about 18 percent to 19 percent moisture content if the start of drying is delayed to Nov. 1. The corn can be dried to about 14.5 percent if the drying air is heated about 5 degrees. The expected cost using off-peak electric heat at 4 cents per kwh is about 24 cents per bushel; it’s about 30 cents per bushel using propane. The expected drying time is at least 60 days, so drying will not be completed until the end of December if using an airflow rate of 1.25 cfm/bu, and later at lower airflow rates.
  • The cost to dry corn from 21 percent to about 14 percent using a natural air-drying system in the spring is about 8 cents per bushel. That is based on drying starting about April 1 when outdoor temperatures average above freezing. Corn at moisture contents up to 21 percent can be stored through the winter by cooling the corn to about 20 degrees and aerating periodically to keep the corn cool during February and March.
  • Estimate high-temperature drying energy costs per bushel per point of moisture removed by multiplying the propane price per gallon by 0.022. For example, the cost of using $1.40-per-gallon propane is 2.9 cents per bushel per point of moisture ($1.40 per gallon x 0.022).
  • Determine the estimated energy cost to dry corn per bushel by multiplying the cost per point of moisture removed by the points removed. The energy cost per bushel to dry corn from 21 percent to 15 percent (6 points) is 17.4 cents per bushel (6 points x 2.9 cents per bushel per point of moisture). Total drying costs are higher since they include both energy costs and the fixed or capital costs.
  • High-temperature drying is most energy efficient using the maximum air temperature permissible without damaging the corn. For example, for a high-temperature dryer airflow rate of about 75 cfm/bu, the energy required to remove a pound of water from corn is about 2,500 British thermal units (Btu) at 210 degrees and about 3,800 Btu at 150 degrees.
  • Energy-efficiency features on high-temperature dryers, such as heat reclaimers and vacuum cooling, reduce the drying cost.

“Drying costs are affected by many variables, so these numbers should be considered as estimates,” Hellevang says. “Accurate records of fuel and other energy costs, as well as the amount of corn dried, including initial and final moisture contents, enable drying management.”

The NDSU Extension Service has more information on corn drying and storage at http://www.ag.ndsu.nodak.edu/abeng/postharvest.htm.


NDSU Agriculture Communication

Source:Ken Hellevang, (701) 231-7243, kenneth.hellevang@ndsu.edu
Editor:Ellen Crawford, (701) 231-5391, ellen.crawford@ndsu.edu
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