Corn sweat: How crops are amplifying our hot, humid weather

CTV Kitchener: Heightening the humidity Weather patterns aren’t the only thing contributing to hot, humid weather. Marc Venema explains the phenomenon of crop sweat.

It’s so hot out, even the corn is sweating.

OK, so that’s not technically true – but agronomist Peter Johnson says it’s a good analogy for a natural phenomenon that becomes more and more pronounced as temperatures approach and top the 30 C mark.

A more precise term is ‘transpiration’ – the process by which corn crops expel water into the atmosphere, increasing humidity levels.

“It’s a really important part of making that plant able to grow,” says Johnson.

“Corn, right now, can actually transpire … about eight millimetres of water per acre per day. That’s a lot of water.”

It’s not a circumstance unique to corn – all plants transpire, including trees and grass – but the rapid growth of corn crops at this time of year makes the effect more pronounced.

Johnson says the easiest way for anyone to understand the effects of transpiration is for them to walk into a cornfield and feel the difference in the air.

“Once you go in there, it’s a bit like a jungle. You will start to sweat almost immediately,” he says.

Corn crops will stop their surge in the next few weeks, but that doesn’t mean an end to transpiration increasing humidity levels.

August is when soybean crops start to take off – meaning ‘soybean sweat’ is the next phenomenon we’ll see.

With reporting by Marc Venema