Tips for 2023 Harvest: Handling grain when moisture is low and variability is high

September 25, 2023
ICM News

Across Iowa, grain harvest is ramping up. A challenge this harvest season will be dealing with variable grain moistures from field to field as well as within individual fields. Additionally, drought conditions that have persisted all year and rapid accumulation of growing degree days are leading to grain that quickly became overly dry. Follow the below set of tips to limit yield loss this fall.

Harvest fields with poor stalk quality first.

Combine dumping harvested corn.Standability of corn stalks is a widespread concern this fall, as noted in a recent ICM blog post. In fields with lodging, make appropriate harvest adjustments, especially to the combine header, to better pick up those stalks. Follow combine adjustment tips as mentioned in a past ICM blog article.

Adjust combine settings more frequently as conditions change within fields.

Inspect combine parts and repair or replace any worn or damaged parts. Also take the time to check that all sensors are working. During harvest, adjust the following three key areas to keep combine machine losses low:

Combine head adjustments:

For corn, set the deck plates so they are tapered from front to back, with 1/8-inch less gap between the plates at the leading edge than at the back. With adjustable deck plates, set them initially using the operating manual and then adjust based on stalk node size so that there is a small gap between stalks and plates. Ideally, the gap between the plates should be narrow enough to avoid shelling kernels, but not so narrow as to cause stalk wedging or pushing over stalks. Reducing header speed can also reduce butt shelling kernels.

For soybean, prevent gathering losses by ensuring the cutterbar condition is good and knife sections and ledger plates are sharp. Soybeans will likely be brittle this year as the likelihood of excessively dry beans is high. If shatter losses are high, try reducing the reel speed, but not so much that stalks begin to drop. Lower reel height when plant height is short, but the minimum should be set so there is always at least a two-inch gap between the reel finger tips and the flexible cutter bar with the bar at its highest position.  

Threshing and separation unit adjustments:

Overly dry grain is brittle and more susceptible to breaking; the threshing system is the primary risk for breakage. Adjust the clearance between the rotor and the concave to reduce damage by narrowing or widening it in increments until it is narrow enough to thresh out the grain while minimizing damage. Because threshing of drier corn is easier, you may be able to adjust settings to be less aggressive and still get efficient threshing. Decrease rotor speed as beans become drier.

Fan speed and sieve adjustments:

Obtaining good separation between the grain and chaff in the cleaning shoe is a function of the cleaning fan air speed and sieve adjustments. When making pre-harvest adjustments, ensure the cleaning fan is functioning well at different speeds. The intent is to be able to match air speed with the crop throughput coming into the cleaning shoe for separation during harvest. Also, ensure that airflow across the cleaning shoe is as uniform as possible for all fan speeds. Sieve adjustments will depend on the kernel sizes passing through the cleaning shoe during harvest. Smaller soybean or corn kernels require narrower sieve openings; however, this can increase the number of larger kernels going back to the threshing unit as part of the tailings.

Measure harvest losses to check whether your combine adjustments are working.

Once well within a field and away from the field edges, stop the combine, back up 15-20 feet, and get out to measure harvest losses. Systematically measure losses following the steps in PM 573 (Profitable Soybean Harvesting) and PM 574 (Profitable Corn Harvesting) to determine if losses are occurring at the header or are going out the back of the combine due to poor threshing and separating. If ear losses are high, also check for ears dropped from the stalk before harvesting to know what your pre-harvest yield loss is.

Core it, cool it, check it.

Overly dry grain can lead to more dust, fines, and mold, so if you aren’t cleaning grain before storing it or spreading grain into the bin, be sure to remove the central core of poorer quality grain before long term storage. It may be necessary to core multiple times as the bin is getting filled. Find information on coring bins in a past ICM blog post.

Grain temperature coming out of the field may be high, especially for corn, so aerate bins immediately to prevent moisture migration. Cool down warm grain this fall in increments as average outdoor air temperature (average of daily high and low) becomes 10-15 degrees less than the grain temperature, eventually getting grain cooled down to between 35-40 degrees for winter storage. Aerate regularly to maintain cool and even grain temperatures and check grain every few weeks throughout the time it is stored.

Record quality factors for the grain in each bin, including moisture content, presence of fines and broken grain, and the test weight, but be aware that test weight might be deceptive due to presence of small kernels. If this is the case, use test weight as an indicator of quality and storability cautiously. Don’t reduce good grain’s quality for storage by mixing with poorer grain. Market off the lowest quality grain first.

Toxins in grain can be a concern in dry and warm conditions, though the risk at this point is uncertain but not likely to be widespread. Eastern Iowa may be more at risk than areas to the west, as the drought moved east toward the end of the growing season. If grain is being fed to livestock, consider sending samples for analysis at a certified lab, such as the Iowa State University Veterinary Diagnostic Laboratory or Eastern Iowa Grain Inspection.

Take care of your greatest asset – yourself and your family.

Keep your health and safety in mind through the rush of harvest, especially with the added stress of challenging conditions. It is even more important this fall that you are wearing a properly fitting NIOSH-approved respirator suitable for grain dusts when you are handling grain.

Take regular breaks and stay hydrated, fueled, and rested to keep your head clear and prevent accidents or injury. Lean on family and friends to help you through this busy time and consider safety along every step of the way to be sure you and your family are around for many harvest seasons to come.

Additional Resources:

Crop standability an issue this fall | Integrated Crop Management (

Profitable Soybean Harvesting, PM573

Profitable Corn Harvesting, PM574

Combine Adjustments for Harvesting Lodged Corn | Integrated Crop Management (  

Fire Prevention and Safety Tips During Harvest | Integrated Crop Management (

Core Each Grain Bin This Fall | Integrated Crop Management (

Calmer Corn Heads - YouTube

VIDEO: Respiratory Protection During Harvest | Integrated Crop Management (

Links to this article are strongly encouraged, and this article may be republished without further permission if published as written and if credit is given to the author, Integrated Crop Management News, and Iowa State University Extension and Outreach. If this article is to be used in any other manner, permission from the author is required. This article was originally published on September 25, 2023. The information contained within may not be the most current and accurate depending on when it is accessed.