Corn: Let it Dry in the Field or Pay for Drying in the Bin?

Every October, farmers face a common question, especially when corn prices are lower than expected: Should I let my corn dry in the field, or should I invest in drying it in the bin? In one recent conversation with a grower, he began harvesting his corn at 26% moisture and achieved a yield of 203 bushels per acre, adjusted to dry bushels. However, when he returned later to harvest the second half of the field, the moisture had dropped to 16%, but the yield was only 189 bushels per acre. So, what happened?

With lower corn prices, it’s tempting to let the corn stay in the field to reduce drying costs. However, there are three key reasons why you might want to consider harvesting corn between 20-25% moisture: phantom yield loss, harvest loss, and fall operation efficiency. Let’s take a deeper dive into each of these factors.

1. Phantom Yield Loss

Phantom yield loss refers to the dry matter loss that occurs in the corn kernels as they respire. Corn seeds are living organisms that continue to use energy reserves as they dry in the field. When humidity and temperature rise, this process accelerates. As the corn dries down, the environment inside the husk can become very humid, which doesn’t allow the kernels to dry effectively. In some cases, the corn may be exposed to rain or humid weather, which causes the kernels to reabsorb moisture and begin to sprout. This reduces grain quality, test weight, and overall yield.

Research from Purdue University shows that leaving corn to dry in the field can cause yield losses of 0.6% to 1.6% per point of moisture. Although it’s difficult to measure phantom yield loss precisely, farmer experiences and plot trials suggest that it can significantly impact overall yields.

2. Harvest Loss

As the corn continues to dry and die in the field, the integrity of the stalks weakens, which leads to more stalk and root lodging. This results in more ears dropping to the ground during harvest. Once an ear falls, it’s lost, leading to a decrease in harvested bushels. Additionally, the stripper bar on the combine can experience more butt shelling and ear loss while harvesting drier corn compared to corn harvesting at a higher moisture content.

In fact, combine header loss can increase by as much as 6% when harvesting dry corn. A timely harvest not only helps to reduce ear loss but also minimizes the risk of ear rot. Ear molds tend to enter the plant during pollination, and its growth accelerates during dry down, especially under humid conditions.

3. Fall Operation Management

A timely harvest doesn’t just mean fewer losses, it can also streamline your entire fall operation. Harvesting early can help reduce wait times at the elevator, speed up your overall harvest, and free up time for post-harvest tasks: tillage, field cleanup, and apply fall herbicides or spreading manure. It may also give you extra time to plant cover crops before the weather turns cold.

Additionally, drying corn in the field could cost you more in the long run, especially when you factor in rising energy costs. It's generally cheaper to dry corn in October because it requires less energy to warm the incoming air. To warm air by just 20 degrees, you need 1% more energy. For a 200-bushel corn crop, this means an extra 1.5 bushels in drying costs due to the cooler temperatures.

Cost Analysis Example

Let’s break down the costs using a common scenario:

• Elevator drying fees: $.03 per point of moisture per bushel + shrink
• Cost to dry corn from 22% to 15% moisture: $.21 per bushel
• Drying cost on 200-bushel corn: $42 per acre
• With corn priced at $3.25 per bushel, it takes roughly 13 bushels to cover the drying costs

However, if you let the corn dry in the field, you could lose more than 10 bushels per acre due to phantom yield loss and harvest loss. In this example, the drying cost is much lower than the potential loss in yield.

So, although the numbers might not always align perfectly, taking everything into account—weather conditions, field health, and operational efficiency—makes it clear that harvesting corn at 20-25% moisture can save you money in the long run, both in terms of drying costs and overall yield.

Conclusion: The Ideal Harvest Moisture

While the temptation to let your corn dry in the field is understandable in years with lower prices, my experience suggests that the optimal moisture range for harvesting is between 20-25%. This window minimizes yield loss, reduces harvest losses, and supports a more efficient fall operation.