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Drying Corn in the Field or with Heated Air – What Are the Trade-offs?
By Sam McNeill, Ph.D., P.E. Associate Extension Professor Food and Bioprocess Engineering
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Should you dry corn in the field or with heated air? What are the trade-offs? The answer depends on grain and energy prices, the number of days to complete harvest, weather and crop conditions as corn remains in the field, and the amount of machine losses that will occur during harvest. If dried in the field, stalks can weaken and/or become lodged, which can lead to increased pre-harvest losses (ear drop); a slower ground speed for the combine (to reduce header losses); and a longer harvest period (which can compound both losses). While harvest has begun in the western part of the state, it won’t be in full swing for the rest of the state until mid-September this year.
Measuring Harvest Losses
To answer the question for an individual farm, you need to know how to measure total harvest losses and strive to keep them below the average level reported for the
Midwest, which is five percent. With this year’s predicted new record average yield for Kentucky (181 bu/ac) and current average cash price ($3.60), average harvest losses amount to $33 per acre. If harvest losses were reduced to two percent or increased to eight percent by stalk deterioration or heavy storms, the costs would be $13 and $52 per acre, respectively.
Compare these to the costs of drying, which depends on the incoming corn moisture, energy efficiency of the dryer, and cost for fuel (LP or natural gas). An average drying efficiency for new and existing grain dryers is around 1750 Btu/lb of water. If LP costs $1.00 per gallon, the cost to dry corn to 15 percent moisture from harvest levels of 30, 25 and 20 percent moisture would be $40, $31, and $18 per acre, respectively. This range of values is anticipated this
season, but producers can use their own values to quickly estimate a meaningful comparison for their operation. A spreadsheet has been posted on the UK Biosystems and Agricultural Engineering Department website, www.uky. edu/bae/ext/grain-and-energy-calculators, to facilitate this comparison. The table below illustrates the costs per acre for a typical range of corn yields and anticipated harvest losses for the corn and fuel prices shown. The returns to drying are calculated both for fuel costs alone (assuming the dryer has been paid for) and for ownership costs (which includes drying energy, depreciation, repairs, labor, and hauling costs).
Excellent Weather Conditions
On the positive side, weather conditions should be excellent for field drying during the next couple of weeks, with sunny daytime temperatures in the upper 80s and nighttime temperatures in the mid-60s. Another positive is that most fields are dry, so the root system will act as an anchor to hold the plant in place during harvest and allow the stalk to feed into the combine with minimal shatter at the header.
The BAE Extension Newsletter is published quarterly by the University of Kentucky Biosystems and Agricultural Engineering Department. ©2019
Editorial Committee Director: Michael Montross, Ph.D., P.E. Editor, Designer: Karin Pekarchik Contributors: Carmen Agouridis, Ph.D., PE, M.P.P., Matt Dixon, Morgan Hayes, Ph.D., PE, Joshua Jackson, Ph.D., Doug Overhults, Ph.D., PE, Mark Purschwitz, Ph.D., Sam McNeill, Ph.D., PE, Tim Stombaugh, Ph.D., PE.
Contact the editor: karin.pekarchik@uky.edu
Educational programs of Kentucky Cooperative Extension serve all people regardless of economic or social status and will not discriminate on the basis of race, color, ethnic
In a typical year, the decision of when to harvest corn largely depends on the cost tradeoff between excess harvest losses and energy costs for drying. Excess losses are those incurred by leaving the crop to dry in the field. With timely harvest, field losses can average less than two percent of the yield, but if the crop remains in the field to dry to 15 percent moisture, yield losses in Kentucky have recently been shown to increase to 19 percent!
Examples shown in the tables illustrate the impact of harvest losses on potential profit for the corn enterprise with anticipated grain and fuel prices. Specific cost comparisons between field drying and heated air drying can be made with the spreadsheet tool available at the UK Biosystems and Agricultural Engineering Department website, www.uky. edu/bae/ext/grain-and-energy-calculators.
Sam McNeill, Ph.D., PE, is an Extension Professor in Food and Bioprocess Engineering.
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