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When should corn harvest start?

When should I harvest my corn? Some might think that is a silly question with a simple answer.

When should corn harvest start?

When should I harvest my corn? Some might think that is a silly question with a simple answer.

But there is much more to consider than just harvesting the crop when it’s ready.

We all remember cold, wet years with delayed harvests and even winter/spring combining. Try to suppress those ugly In 2012, we had a very dry crop. But typically, we have corn moistures in the low 20s.

What is the ideal range for corn moisture? My target is 17%-23%. This range may be expanded when considering acreage constraints, harvest timing or storage needs.

Key Points

When to start harvesting corn depends on several important things.

Moisture content, drying system and time of year all factor into the decision.

Peterson Farms Seed agronomist says 17%-23% moisture is a good target.

The top end of the 17%-23% moisture range is significant. At 23% moisture, corn can still be safely stored in a natural-air bin over winter without the possibility of kernels freezing together.

Many new corn producers in the region rely on natural-air bin drying, as it allows grain to be harvested quickly and usually leads to good grain quality, once dry.

When corn is more than 21% moisture, it should be dried with heat late in the season to reduce spring spoilage risk.

When moisture percentages approach the upper 20s, there is a greater chance for mechanical damage, leading to reduced storage time and possible lower test weights.

In 2008 and 2009, many growers experienced issues with grain bridging and fans icing up. These situations are dangerous and should be avoided if possible.

High-temperature drying is common for most parts of the corn-growing region, and it allows for easier storage. Growers may also see both marketing and hauling advantages in the winter with dry grain.

Most dryers are sized to reduce grain moisture by 5%. Some producers will use high temperatures to dry the grain down to the upper teens, followed by drying the rest of the way with natural air.

During this process, grain quality should be inspected repeatedly. Heat damage can easily occur, especially when attempting to reduce moisture by more than 10%.

On the other hand, grain that is too dry at harvest is at the greatest risk for yield loss. Fortunately, we do not experience this very frequently.

Header loss is the biggest risk and ranges from 0.5%-3%. It is most affected by low grain moisture, harvest speed, gathering chains, stalk rolls and deck plates.

A majority of harvest losses are at the gathering unit. These losses can be assessed by measuring behind the header and the combine.

Two kernels per square foot equates to 1 bushel per acre of loss. Keep these losses under 1%.

With the lower commodity price outlook for the upcoming year, you’ll want to sell every kernel you’ve got.

That means harvesting all kernels produced, as well as maintaining the quality of those kernels.

Take your time this fall to harvest at the proper moisture. Wishing you a safe and productive harvest!

Spelhaug is an agronomist with Peterson Farms Seed, Harwood, N.D. Follow him on Twitter at @PFSAdam, and read his contributions to The Peterson Blog at

For more information, contact him at 866-481-7333 or




This article published in the October, 2014 edition of DAKOTA FARMER.

All rights reserved. Copyright Farm Progress Cos. 2014.

Crop Management

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