Seem more humid these days? That’s because it probably is.

Note: The first version of this post was wrong, and thanks to commenter R. Anderson for pointing it out. Below is the new and (I’m fervently hoping) improved post. Math and I have never gotten along, and it doesn’t seem to be getting better the older I get…

Each summer, the Matiles up-stakes and head for Wisconsin’s Northwoods for periodic respites from the plague of corn pollen around these parts. The trips are unfortunately brief, but the respites are always welcomed.

I’ve been plagued with an allergy to grass pollen my entire life, something that makes living out here on the Illinois prairie during the summer months a trial. If it isn’t one kind of grass pollinating, it’s another. And a corn stalk, after all, is just a giant blade of grass.

Getting out of town this time of year, in fact, is a fine old Oswego tradition. On Aug. 19, 1880, the Kendall County Record reported from Oswego that: “Dr. Lester has gone to spend some time on the Atlantic coast in Canada and Maine for the purpose of escaping the hay fever.” So I’m in good historical company, at least.

And corn just doesn’t affect us allergy sufferers, either. I saw a piece on the Weather Channel the other day about the effect all those fields of corn have on the weather here in northern Illinois. It turns out it’s a fairly large impact, especially on the fields’ impact on the region’s humidity.

In fact, it’s probably a lot more humid during mid-summer days now than it was 60 years ago, thanks to all that corn.

Why?

Graeme Stewart used Case equipment to pick and husk the corn on his farm in Oswego and Wheatland townships back in 1938. Note how far apart the rows of corn are, as well as the space between each individual corn stalk. In pre-herbicide days, corn was planted at greater intervals to allow for more efficient mechanical cultivating.

In 1950, the U.S. Farm Census reported that Kendall County farmers grew about 80,000 acres of corn. During that era, individual corn plants were not spaced very close together. In fact, some farmers preferred to check or horse-step corn when they planted it, leaving an equidistant space between each individual stalk of corn and its neighbors. That allowed farmers to use their tractor-mounted cultivators to first run one direction, and then to do the field again perpendicular to the first go-round in order to get the weeds on all four sides of each stalk. That made a lot of sense in those pre-herbicide days when weeds had to be removed by hand.

By 2007, Kendall County farmers were planting more than 102,000 acres of corn. The increase in acreage was due to a number of factors, but was primarily caused by the shift from diversified farming, where each farm grew grain, forage, and livestock to today’s modern farming operations that specialize in either grain or livestock. All those fields in the 1950s that were dedicated to pastureland or planted in alfalfa and other forage crops, or oats and wheat are now planted in corn.

And not only are more acres of corn being cultivated in rural Illinois these days, but the corn plants themselves are much different than the ones farmers planted 60 years ago. Today’s corn is taller than its ancestors, grows much faster, and the plants are planted much more closely together.

In this photo of a modern corn field, note how much closer together the rows of corn are, and how much closer together each individual corn plant is than they were in the photo taken of Graeme Stewart’s 1938 harvest.

These days, according to Delta Farm Press, farmers grow an average of 36,000 closely spaced corn plants on an acre of land. In 1900, according to Bulletin 111, “Corn Culture,” published by the Alabama Agricultural Station at Auburn, farmers were planting less than 3,200 plants per acre. Through the years, that number increased thanks to more efficient mechanical planters, better strains of corn, hybridization, and introducing better fertilizers. By the 1950s, Midwestern farmers were planting at least 10,000 plants per acre, and now they’re growing more than three times as many plants per acre.

Through the growing season, each one of those corn stalks draws a tremendous amount of water out of the soil for growth, and then transpirates 53 gallons of excess water into the atmosphere, most of it expelled during the prime growing season of July and August.

So do the math: Every modern acre planted in corn transpirates a total of nearly 2 million gallons of water during the growing season, with the bulk of it being expelled during the prime July and August growing season. And with Kendall’s 102,000 acres of corn, that means the plants are pumping 189 billion (that’s billion with a “b” son) gallons of water into the air during an average year. Back in 1950, each acre of corn was pumping out 530,000 gallons of water a season, which means, the county’s corn crop was transpirating 42.4 billion gallons of water into the atmosphere from early June through late September. That means about four and a half times the amount of humidity is being released today compared to 60 years ago.

An acre of prairie grass or other crops such as oats or wheat also transpirates water into the atmosphere, but at less than half the rates compared to corn.

So, it’s no wonder it seems a mite muggier around these parts nowadays. Crop scientists and meteorologists claim that dense corn fields can raise the dew point—the amount of humidity at which us humans become uncomfortable—by more than 10 percentage points or sometimes even more. The difference in the way you feel outside between a dew point of 50° and 70° is considerable.

And, of course, that’s just Kendall County. Head west on U.S. Route 30 or U.S. Route 34 or a country road like Galena Road, or south on Ill. Route 71 or Route 47, and you’ll see that there are millions of acres of corn in pretty close proximity to us here in the mid-Fox River Valley in DeKalb, Grundy, LaSalle, Kane, and all the other counties west to the Mississippi and south all the way to Marion and north to the Wisconsin border.

So yes, it was hot when I was a kid growing up, first on a farm out in Wheatland Township, and then here at the Matile Manse in Oswego, but it seems fairly clear that it probably wasn’t nearly as humid in July and August as it is these days.

 

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