Agricultural Heat Islands

US summer afternoon temperatures have not increased over the last 60 years, but nighttime temperatures have.

The increase correlates with the increase in corn yields in the US.

Corn yields in the United States, 1866 to 2014

Cornfields increase humidity which produces higher nighttime temperatures and lower afternoon temperatures.

How does corn affect Midwest weather?: University of Illinois Extension

How cornfields make Midwest unbearably humid | The Gazette

‘Sweaty’ Cornfields Cause U.S. Heat Wave | GearJunkie

Corn Belt States – Vivid Maps

The average daily temperature range during summer has declined sharply in the US since the 1930s drought.

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13 Responses to Agricultural Heat Islands

  1. Bob Gutjahr says:

    The son of an Illinois farmer once told me that corn yields the most food per acre of any crop. Note the push to reduce the food supply.

  2. GreyGeek says:

    Temperatures in North America range between -15F and 110F, ignoring outliers.
    If that average nighttime temperature graph was plotted between the ranges the up slope would not be as steep.

    Our former governor and senator, Ben Nelson, campaigned using the slogan “let’s replace oil fields with corn fields”. The federal and state governments began subsidizing Ethanol plants in order to replace gasoline with Ethanol, a really stupid idea because it takes 7 gallons of Ethanol to replace 1 gallon of gas and America doesn’t have enough friable land to grow the corn needed to replace all the gasonline. The price of corn had been hoovering around $2.40/bu for years but the demand for corn by the 18 Ethanol plants in Nebraska caused the priced of corn to explode to $6/bu. Farmers went wild. Farmers used to plant fence-to-fence but they pulled down the fences and planted road-to-road. In some cases they plowed up the roads to create larger planting areas. Then the subsidies were canceled and Ethanol plants began closing because producing Ethanol for fuel is not economically self-sustaining. It still isn’t. Federal and state tax credits and incentive programs cut in and Ethanol plants resumed, amounting to around 50 cents/gal. Today, there are 24 Ethanol plants in Nebraska and 40% of our corn is used to manufacture Ethanol. And, they claim that they are not subsidized, despite the Federal blending mandates.
    https://afdc.energy.gov/fuels/laws/ETH?state=US
    Farmers in Western Nebraska can’t grow corn so they grow sugar beets, which has a MUCH HIGHER concentration of sugar than corn and is a more efficient producer of Ethanol because the enzyme can act directly on the sugar, unlike corn starch, which has to be broken down first. Ten years ago Nebraska produced 2.1 billion gallons of Ethanol. This year they will produce 2.2 billion gallons.
    Corn farmers are suing the Ethanol plants that are accepting sugar beets.

  3. Conrad Ziefle says:

    This seems to be a thermodynamic phenomena having to do with the formation of vapor during the day and the condensation of vapor at night. I’m supposing that during the day the humidity is raised, i.e. heat makes water vaporize rather than raising the temperature. And at night, condensation releases heat keeping the night temperature higher than normal- or something along that line. And over the day it balances out. The cornfields are a thermal storage device that cycles daily. When you say that the average daily temperature has decreased since the 1930s, I’m assuming you mean average 24-hour day temperature.
    I have thought that if there were anthropogenic climate change it would be caused by terraforming, not fossil fuel burning. I’m assuming that, as above, the cornfields are a daily phenomenon, will no net heat gain. But if there is a net heat gain from increased plant growth, then we have to decide whether a flourishing biosphere is worth a slight temperature increase. And there are a lot of issues rolled into that. Certainly, you have to wonder about the ethics of curtailing food production, i.e. is starving and depriving people ethical, just to maintain a pristine “temperature”, when we have no idea what that really is.

  4. Steve Cooksey says:

    Maybe those area need to add more black solar panels to the landscape. Really heat it up.

  5. Russell Cook says:

    Plow all of the corn crops under. Problem solved.*

    *(oh, wait …. that kills the super green renewable fuel ethanol, and all the government subsidies keeping that industry afloat)

  6. spren says:

    Adding ethanol to gasoline was meant to replace MTBE as a re-oxygenator of the fuel to make it burn more cleanly. MTBE was a previously forced additive by government until it was found to be one of the most toxic chemicals ever created and destroyed many water supplies. Adding ethanol to gasoline is a really stupid idea and only survives because of politicians fear of the Iowan farmers who have become addicted to their corn subsidies.

  7. spren says:

    I am also very skeptical of the claim that an acre of corn releases 4000 gallons of water every day. I would say that claim is releasing 4000 bushels of BS.

    • tonyheller says:

      The majority of all water use in Colorado is growing corn.

    • D. Boss says:

      spren: an acre is 43,600 square feet. 4,000 (US) gallons divided by 43,600 is 0.09174 gallons per square foot. Which is 11.7 fluid ounces or 347 milliliters – a soda can is 12 fluid ounces. So a square foot of ground in a cornfield releasing just under a Coke can’s worth of water per day is not unreasonable.

      Furthermore, a typical mature cultivated corn plant has 16 leaves, each having approximately 44 square inches area. (range is from 20 to 68 in²) So a typical corn plant has 704 square inches of leaf area, which is 4.89 square feet. So that 11.7 fluid ounces of water, assuming 1 corn plant per square foot of ground is reduced to 2.39 fluid ounces of water per square foot of leaf area, OR is reduced to 0.73 fluid ounces per leaf. ( which is 21.6 milliliters water lost per day per corn leaf) (or 1.46 tablespoons per leaf per day)

      I was always taught to be skeptical, but not just to be an ass, test what you are told, or cross check it via alternate methods. (it took me about 10 minutes to look up the relevant data here and do the simple calculations)

      My conclusion: 4,000 gallons per day per acre is a sensible number.

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