In the heat of a Wisconsin summer, a hard day’s work can really work up a sweat – just ask a cornstalk.
A process known as evapotranspiration, commonly called “corn sweat,” happens when corn and some other plants release moisture into the atmosphere. In the Midwest, where corn grows in massive quantities, it can make humid conditions feel even muggier.
Taranis, a crop intelligence firm, says corn sweat is a sign of healthy growth. But what exactly is it and how much do cornstalks actually sweat?
How does ‘corn sweat’ really work?
Corn absorbs water through its roots, and that water eventually works it way up the stalk, nourishing the plant and serving vital functions, including photosynthesis.
Once it reaches the leaves and top of the stalk, the moisture is released into the atmosphere. The moisture is released through stomata, which are microscopic pores on plant leaves and stems.
In farm fields where corn grows in row after row, those tiny pores can release an “astonishing amount of moisture,” according to Taranis.
How much does corn actually sweat?
Just one acre of corn can release between 3,000 and 4,000 gallons of water into the air every day during peak growing season, according to the U.S. Geological Survey. A single leaf will release quantities of water many times more than its own weight.
In 2025, 4.15 million acres of corn were planted across Wisconsin, according to the state agriculture overview. That equates to up to 16.6 billion gallons of water per day, or enough to fill over 870,000 swimming pools.
In other states, such as Illinois and Iowa, corn sweat totals can top more than 40 billion gallons of water each day.
Do other plants sweat too?
Evapotranspiration happens with all vegetation, Iowa state climatologist Justin Glisan told USA TODAY in 2025.
That includes other varieties of crops planted in Wisconsin, such as soybeans. The state agriculture overview estimated just over 2 million all-purpose acres of planted soybeans in 2025.
Similarly, the U.S. Geological Survey says a large oak tree can “sweat” 40,000 gallons of water per year.
How does corn sweat affect the weather?
Research from Illinois state climatologist Trent Ford suggests that while it can be a factor, corn sweat is not the most significant cause for low-level humidity in the Midwest, with other factors including large-scale atmospheric conditions.
Lance Schulteis can be reached at LSchulteis@usatodayco.com.
This article originally appeared on Milwaukee Journal Sentinel: How does corn ‘sweat’ and why does it affect Wisconsin weather
Reporting by Lance Schulteis, Milwaukee Journal Sentinel / Milwaukee Journal Sentinel
USA TODAY Network via Reuters Connect
By Lance Schulteis, Milwaukee Journal Sentinel | USA TODAY Network
