'Corn Sweat' Doesn't Cause High Humidity in the Hoosier State
Published: Friday, August 1, 2025
The following is from Jeff Burbrink, LaGrange County Extension educator.
After my third conversation in two days about corn sweat, a popular media topic for the past three summers, I want to put things into perspective.
1. Corn is not responsible for our Midwest humidity.
2. Corn is a warm season grass, and it thrives in warm, humid conditions. That's why it is so well suited to our climate.
3. Indiana is a humid state. It was humid before corn dominated the landscape.
4. If corn was responsible for humidity, then Nebraska would be humid, too. Nebraska is an arid state where a lot of corn is grown. You don't see the "humidity haze" hanging over Nebraska like you see in this part of the Corn Belt. They just have a different climate than us.
And about good watering practices in general, with a focus on backyards ... :
5. All plants use water. The use of the water combined with evaporation for the soil is called evapotranspiration. Most plants need the equivalent of 1 to 1.5 inches of rainwater per week in our region.
6. A water use example: A maple tree uses 10 gallons of water per inch of diameter during the summer. So a 3-inch diameter tree (3 inches at breast height) needs about 30 gallons a day during the summer. A 10-inch tree uses 100 gallons of water in a day during the summer. Think about that. A 10-inch diameter tree will use 700 gallons of water in a week!
7. When watering plants, its best to apply water infrequently and deeply. Try to wet the soil to a depth of 12 inches. That is the equivalent of about 1 inch of rain.
8. How long does that take to apply an inch of water? Depends on many things: water pressure, irrigation method, soil type, etc. It might be anywhere from 30 minutes to five hours depending on the setup. The best way to figure it out for your individual situation is to place a straight sided container in the lawn at various distances from the sprinkler head, and measure how long it takes to collect 1 inch. I use a straight sided coffee cup. Each zone in an irrigation system should be evaluated separately.
9. When watering trees, apply the water to an area about 1.5 times as far from the trunk as the branches extend. So a tree with a branch reach of 30 feet should be watered out to a distance of 45-50 feet for best results.
10. Applying water at a trickle right next to the trunk of a mature tree does not do a lot for tree health. Those roots at the base of a big tree are there for support more than for water uptake.
11. In extremely hot weather, water might need to be applied to gardens and lawns two to three times a week to keep up with plant needs.
12. In cooler parts of the season, water may need only be applied if Mother Nature does not provide an inch of rain or so a week. A rain gauge can help you understand how much rain you've had in your backyard. Simple rain gauges are relatively inexpensive.
13. Many people and businesses have automatic irrigation systems set up for daily, brief watering. This encourages shallow rooting, more weeds, and more disease issues. Again, the best way to water is infrequent, a deep soak ( 1 foot or so) watering.
14. Watering in the morning tends to be more efficient. Less evaporation loss. And less disease pressure. The longer a plant is wet, the better the chance of disease issues.
15. Example: Watering after you get home from work in the evening keeps the plants wet for hours overnight = higher chance of foliar disease. Watering from 5-7 a.m. will minimize the time the plants are wet.
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