topsoil

The majority of food we eat is grown in topsoil, that carbon-rich, black soil that nurtures everything from carrots to watermelons. The fertility of this soil has developed over eons.

But over the past 160 years, the Midwestern United States has lost 63.4 billion tons of topsoil due to farming practices. In fact, Midwestern topsoil is eroding between 10 and 1,000 times faster than it did in the pre-agricultural era. The rate of erosion is 25 times greater than the rate at which topsoil forms.

According to new research from the University of Massachusetts-Amherst, this rapid and unsustainable rate of topsoil erosion can be drastically reduced by utilizing an agricultural method already in practice: No-till farming. This method, which is currently practiced on 40% of cropland acres in the Midwest, can extend our current level of soil fertility for the next several centuries.

In the study, which was recently published in the journal Earth’s Future, the research team looked at the current business-as-usual method, under which approximately 40% of the midwestern U.S.’s acres are no-till farmed, all the way up to 100% adoption of no-till methods.

If the U.S.’s current agricultural practices remain largely unchanged, approximately 9.6 billion tons of topsoil will be lost over the next century alone. However, approximately 95% of the erosion in the business-as-usual scenario could be prevented by adopting 100% no-till farming practices.

Saving our soil by improving our farming methods has implications for everything from food security to climate change mitigation.

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Saving Our Soil: How to Extend U.S. Breadbasket Fertility for Centuries

Photo, posted January 19, 2022, courtesy of Terri Dux via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio

According to a new study published in the Proceedings of the National Academy of Sciences, more than a third of the farmland in the U.S. Corn Belt has completely lost its carbon-rich topsoil due to erosion. The affected area is nearly 100 million acres and the amount of carbon loss is nearly 2 million tons.

The study, led by scientists at the University of Massachusetts, Amherst, found that the greatest loss of carbon-rich topsoil was on hilltops and ridgelines. This indicates that tillage – the repeated plowing of fields – was the primary cause of the erosion because loosened soils move downslope.

The loss of topsoil has reduced corn and soybean yields in the Midwest by 6%, resulting in a loss of nearly $3 billion a year for farmers. In addition, the loosening of the topsoil increases runoff of sediment and nutrients into nearly waterways, worsening water quality.

Previous studies have shown that no-till farming practices can have a significant impact on reducing erosion. A study published last November found that if farmers shifted entirely to no-till practices, it would reduce soil erosion from U.S. agricultural fields by more than 70%, as well as significantly reducing nutrient and sediment runoff.

No-till farming is the practice of planting crops without tilling the soil. Instead, seeds are planted through the remains of previous crops by planters or drills that cut seed furrows, place the seeds, and close the furrow. Currently less than 15% of farmland in the upper Mississippi River watershed is farmed with no-till practices.

Even partial changes in tilling practices could produce positive results for topsoil retention and for waterways.

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One-Third of Farmland in the U.S. Corn Belt Has Lost Its Topsoil

Photo, posted September 15, 2010, courtesy of the United Soybean Board / Soybean Checkoff via Flickr.

Earth Wise is a production of WAMC Northeast Public Radio.

Saving Our Soil | Earth Wise

The majority of food we eat is grown in topsoil, that carbon-rich, black soil that nurtures everything from carrots to watermelons. The fertility of this soil has developed over eons.

Web Links

The Corn Belt Is Losing Topsoil | Earth Wise

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