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posted by janrinok on Saturday January 21 2023, @07:27PM   Printer-friendly
from the dishing-the-dirt dept.

First precise calculation of the pre-agricultural rate of erosion across the Midwestern U.S., thanks to exploding stars:

In a discovery that has repercussions for everything from domestic agricultural policy to global food security and the plans to mitigate climate change, researchers at the University of Massachusetts recently announced that the rate of soil erosion in the Midwestern US is 10 to 1,000 times greater than pre-agricultural erosion rates. These newly discovered pre-agricultural rates, which reflect the rate at which soils form, are orders of magnitude lower than the upper allowable limit of erosion set by the U.S. Department of Agriculture (USDA).

The study, which appears in the journal Geology, makes use of a rare element, beryllium-10, or 10Be, that occurs when stars in the Milky Way explode and send high-energy particles, called cosmic rays, rocketing toward Earth. When this galactic shrapnel slams into the Earth's crust, it splits oxygen in the soil apart, leaving tiny trace amounts of 10Be, which can be used to precisely determine average erosion rates over the span of thousands to millions of years.

[...] The numbers are not encouraging. "Our median pre-agricultural erosion rate across all the sites we sampled is 0.04 mm per year," says Larsen. Any modern-day erosion rate higher than that number means that soil is disappearing faster than it is accumulating.

Unfortunately, the USDA's current limit for erosion is 1 mm per year—twenty-five times greater than the average rate Larsen's team found. And some sites are experiencing far greater erosion, disappearing at 1,000 times the natural rate. This means that the USDA's current guidelines will inevitably lead to rapid loss of topsoil.

[...] Yet, there's no reason to despair. "There are agricultural practices, such as no-till farming, that we know how to do and we know greatly reduce erosion," says Quarrier. "The key is to reduce our current erosion rates to natural levels," adds Larsen.

Journal Reference:
Caroline L. Quarrier, Jeffrey S. Kwang, Brendon J. Quirk, et al.; Pre-agricultural soil erosion rates in the midwestern United States. Geology 2022;; 51 (1): 44–48. doi: https://doi.org/10.1130/G50667.1


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  • (Score: 2) by krishnoid on Sunday January 22 2023, @02:34AM (3 children)

    by krishnoid (1156) on Sunday January 22 2023, @02:34AM (#1288000)

    If you don't do that, don't you need a thatch rake or something so they don't mat down on the dirt and build up?

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  • (Score: 4, Informative) by optotronic on Sunday January 22 2023, @03:02AM (1 child)

    by optotronic (4285) on Sunday January 22 2023, @03:02AM (#1288007)

    Not if you use a mulching mower and mow often enough for the clippings to disappear into the lawn. Typically that means cutting no more than 1/3 off the grass blades. In the spring you may have to mow more often than once a week; in the heat of the summer, maybe once every two weeks. At least that's how it works with cool season grasses in the midwest.

    It should be obvious that mulch mowing is less work than bagging and disposing of clippings, then adding compost to make up for the loss of material.

    If mowing more often than once a week when the grass grows fast is too much for you, note that cutting off more than 1/3 of the grass blades is bad for the lawn.

    Mowing lawns is a lot of work and the best solution is to eliminate the lawn in an environmentally friendly manner. Sadly, I don't think that's allowed in most communities where the rules, presumably unintentionally, hasten the destruction of the environment.

    • (Score: 3, Insightful) by quietus on Tuesday January 24 2023, @01:10PM

      by quietus (6328) on Tuesday January 24 2023, @01:10PM (#1288340) Journal

      There are rules for mowing the lawn where you live? I slowly start to understand the eternal discussions about governmental overreach in the US.

      (Over here (Belgium) there's a movement afoot *not* to mow the lawn anymore apart from a few times a year -- figured that the sum of lawns, wilded, would dwarf the size of the currently existing nature reserves.)

  • (Score: 3, Informative) by JoeMerchant on Sunday January 22 2023, @02:09PM

    by JoeMerchant (3937) on Sunday January 22 2023, @02:09PM (#1288053)

    Similar to optotronics response: mulching mower, and in Florida if you mow before the grass is 6" tall, you're good: St. Augustine, Bahia, whatever, it will decompose and fertilize the lawn.

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