October 6, 2005

Producers Can Reduce Corn Drying Fuel Costs

With current fuel prices, allowing corn to dry in the field during October normally is profitable, according to Ken Hellevang, a North Dakota State University Extension Service agricultural engineer.

However, artificial drying generally is the better option by the end of October and during November, he says.

Studies have found leaving corn in the field results in losses that vary from 2 percent to 6 percent between mid-October and mid-November and increase to more than 11 percent from mid-November to mid-December. Other studies have found an average increase in field loss to be about 0.3 percent per day, which is about 2 percent per week.

Hellevang recommends producers inspect their cornfields to determine stalk quality. When stalk quality is poor, a significant wind or rainstorm may increase harvest losses dramatically. The value of the field loss during a 10-day delay of harvest in October would be about $4.80 per acre, assuming a loss of 0.2 percent per day on a yield of 120 bushels per acre (bu/ac) and a corn price of $2 per bushel.

The rate of field drying will vary depending on weather conditions, but may be about 0.5 percentage point per day during early October. Therefore, producers can expect about a 5 percent reduction in moisture content during a 10-day period. The cost to remove this moisture (5 percent) using a high-temperature dryer would be about $15.60 per acre using $1.30-per-gallon propane.

To estimate the energy cost for corn drying using a high-temperature column dryer, multiply the cost of propane per gallon by 0.02. For example, 0.02 x $1.30 = 2.6 cents per point of moisture removed per bushel. Natural air drying during October would cost about $7.20 per acre, assuming electricity at 6 cents per kilowatt-hour and a yield of 120 bu./ac.

Hellevang says producers can expect harvest losses to increase during November to about 0.33 percent per day, so the loss is about $8 per acre during a 10-day harvest delay, assuming the same yield and corn price. The rate of field drying will decrease to 0.2 percent or less per day in November. Therefore, field drying during the 10-day period in early November would be only about 2 percent. The cost to remove the moisture using a high-temperature dryer would be about $6.20 per acre.

“The cost of field losses exceed the cost of drying, so drying the corn artificially would be better than waiting for field drying during November,” he says.

The following are some energy-saving tips for drying corn:

• Recycle the cooling air and some of the drying air. A dryer that captures the heat from cooling dry corn and a portion of the air from the final drying portion of the dryer can reduce the energy used to dry the corn by about 20 percent.
• Use dryeration. It can reduce the energy used by about 25 percent. Dryeration is the process of drying corn partially in a high-temperature dryer, allowing it to sit hot in a dryeration bin for at least six hours, cooling it in the dryeration bin and then transferring it to another bin for storage. The dryeration process will reduce corn moisture content about 2 percent to 2.5 percent, so corn needs to be dried to only about 18 percent in the high-temperature dryer. Using dryeration increases the dryer capacity by at least 60 percent.
• Use the maximum drying temperature that will not damage the corn. The amount of energy required to remove a pound of water is about 20 percent less using a drying air temperature of 200 F instead of 150 F.
• Use a newer, more efficient dryer. Newer dryers typically have features to make them more energy efficient than older dryers.

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Source: Ken Hellevang, (701) 231-7243, kjh-eng@ndsuext.nodak.edu
Editor: Ellen Crawford, (701) 231-5391, ecrawfor@ndsuext.nodak.edu

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