09/18/2026
🌱 Field Crop IPM — What’s in the Field?
What’s in the field? … MOISTURE! 💧
As we approach harvest, we need conditions to begin drying out. Unfortunately, this season has given Pennsylvania growers plenty of moisture challenges.
We started the season with an extended drought, resulting in virtually no second-cutting hay in some areas and even barren cornfields in the driest locations. Then the rains came. You can see the variability this season in the graphic.
That change in weather and return in rains have created a new set of challenges. Chopped corn has been wetter than normal, particularly in areas that experienced drought stress. Early soybeans that were just beginning to be harvested at around 12% moisture have now wicked up moisture and are testing in the mid-teens or higher following rainfall. Even high-moisture corn is currently too wet to harvest in some locations.
In other words, moisture is becoming a major management issue this fall.
🌱 Soybeans and Moisture
Soybeans are particularly sensitive to humidity. Depending on sunshine and relative humidity, soybean moisture can change dramatically during a single day. It is possible to see beans test around 20% moisture in the morning and near 10% later in the afternoon under the right conditions.
Once those mature brown pods are set—even if leaves remain on the plant—harvest is approaching quickly, often within about 14 days. Growers need to be watching maturity closely rather than waiting for the entire plant to look completely dry. One of the keys to achieving maximum soybean yields is to take steps to ensure timely harvest. A important first step is a timely harvest of the crop. It has been my experience that once 95% of the pods turn brown, about a week later it’s time to combine. Some recent work at Iowa State showed a 3.2% loss of moisture per day – more than 5 times that of corn. So dry down is quick. The data also suggested about 12 days after pod maturation 13% moisture was noted over the study period. After that period, the dry down rate significantly slows down or stops completely, stabilizing at about 13 percent moisture.
Soybean seeds may absorb moisture from the atmosphere under cold and humid conditions, which can delay dry down. Additionally, in conditions where the atmosphere has a high v***r pressure deficit (warm temperatures with low humidity) soybean grain dry down can reach 9-10 percent grain moisture.
Paying attention to when the soybean crop reaches maturity can help farmers schedule harvest activities. Under average weather conditions, soybean will reach 13 percent moisture in about 12 days following maturity. However, if weather conditions are conducive, grain dry down can be achieved in as early as nine days after maturity.
The article “How Fast do Soybeans Dry Down in the Field? provides more information
It is also important to avoid letting soybeans become excessively dry. Harvesting beans in the 14–16% moisture range can help reduce harvest losses and avoid unnecessary moisture discounts, depending on the elevator or cooperative's pricing schedule.
I remember this being a major difference between Iowa and Pennsylvania when I first came to Penn State. In Iowa, growers would often harvest soybeans as soon as they were ready and then move to corn. In Pennsylvania, I encountered more situations where growers harvested corn first while mature soybeans remained standing.
From an agronomic perspective, that always caught my attention. Once soybeans are fit to harvest, every additional day in the field can increase the risk of shattering, harvest loss and weather-related damage. And while snow can make soybean harvest particularly difficult, standing corn—with ears several feet above the soil surface—can sometimes remain much easier to harvest under snowy conditions.
🌽 Corn and Moisture
Corn is generally more stable than soybeans when it comes to moisture changes, but wet conditions can still create significant harvest problems.
Wet stalks moving through a combine can contribute to shelling and harvesting difficulties. I have seen situations where relatively dry corn was harvested through wet stalk material, resulting in severe butt shelling and additional grain loss.
Growers should also be identifying cornfields for early harvest by checking stalk integrity—using a simple hand-squeeze test for stalk rot and, where needed, cutting plants to evaluate stalk strength. Fields showing significant stalk deterioration or an increased risk of lodging should be targeted for harvest before they go down and create much greater harvest losses and difficulties.
As rains continue to come and go this fall, growers will face increasingly difficult decisions about when to enter the field.
And there is another important consideration: SAFETY.
When rain is forecast—or even when the forecast changes unexpectedly—growers can get into a rush to harvest. That is often when accidents happen. Take the time necessary to make safe decisions, even when the weather is putting pressure on the harvest schedule.
🌾 Moisture Challenges Beyond Harvest
Moisture isn't just affecting corn and soybeans.
Wet conditions are also creating challenges for:
• Hay harvest and storage
• Planting fall small grains
• Manure application
• Field traffic and soil compaction
• Timely harvest operations
So, as we head into fall, it is shaping up to be a challenging harvest season.
🌧️ Make the Most of the Rain Delays
While the rain is keeping us out of the field, there are still productive things growers can do to prepare for the season ahead.
Consider gathering soil tests, collecting late-season stalk nitrate samples, and submitting manure samples for analysis. These are valuable tools for evaluating nutrient management and making informed decisions for next year's crops.
And remember, your friendly Penn State Extension office is available to help with these resources and questions. Sometimes a rain delay is a good opportunity to get some of that important planning and testing done before the combines roll again.
We'll continue to keep you informed from the field as conditions change.
What's in your field? … Keep scouting, keep watching the weather, and keep safety first!
