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Deciding the appropriate moisture level to harvest corn is often an economic decision, weighing excess harvest losses against energy costs for drying corn. Growers should consider the risk of severe lodging and yield losses when making harvest timing decisions.
When corn is mature in the field, it is around the 30% moisture level. Many factors impact how quickly corn dries down in the field after reaching maturity. Warm and dry weather speeds up the crop drying rate, whereas wet and cool weather slows it down. Lateplanted corn or later-maturing corn products dry more slowly. Differences in ear and husk placement among corn products can also affect dry-down rates. Field losses generally increase with delayed harvest.
The optimum harvest moisture for corn is approximately 23-25%. At this moisture level, kernels shell easily and stalks generally stand better, which makes harvesting more efficient. With a timely and efficient harvest, losses should be minimized to 1-2%.
Delaying harvest until corn dries down to around 17- 19% moisture can save considerable artificial drying costs. However, as corn dries down in the field, there is greater potential for excess harvest losses from stalk lodging and ear drop. Most harvest losses are mechanical, caused by kernel shattering or corn never getting into the combine. Allowing corn to dry down in the field could lead to harvest losses as much as 2-8% above the normal levels during a timely and efficient harvest.
Table 1 provides an estimate of the energy cost to dry corn and the value of excess harvest losses based on corn price. Estimates are provided for low (2% above normal), medium (5%), and high (8%) excess harvest loss conditions. When considering both harvest losses and drying costs, the spreadsheet illustrates that harvesting at a higher moisture level can be more profitable than allowing more field drying time, especially when medium to high excess harvest losses are expected.
It can be beneficial to start harvesting early to minimize corn harvest losses. If you see stalk lodging or ear drop problems, harvest timing will be more critical to maximize yield potential. Take the time to watch crop conditions in the field and balance field dry down with harvest losses.
Sources: Nielsen, R.L., 2008. Field drydown of mature corn grain. Purdue University (Corny News Network. Revised July 2008). http://www.agry.purdue.edu (verified 9/2/2011). McNeill, S.G., 2000. When should you start harvesting corn in 2000? University of Kentucky. August 16, 2000. http://www.ca.uky.edu (verified 9/2/2011).
Individual results may vary, and performance may vary from location to location and from year to year. This result may not be an indicator of results you may obtain as local growing, soil and weather conditions may vary. Growers should evaluate data from multiple locations and years whenever possible. ALWAYS READ AND FOLLOW PESTICIDE LABEL DIRECTIONS. Technology Development by Monsanto and Design® is a registered trademark of Monsanto Technology LLC. ©2011 Monsanto Company. 09022011TED