More Reasons to Save Soil with Solar

January 11, 2023

“Six years you shall sow your land and gather in its produce, but the seventh year you shall let it rest and lie fallow, that the poor of your people may eat; and what they leave, the beasts of the field may eat. In like manner you shall do with your vineyard and your olive grove.” Exodus 23:10-11

We have a bias in this country against leaving soil fallow, because we think it’s “not doing anything”.
I’ve often heard the claim that building solar energy on existing farmland is somehow not a good land use.
But the soil around solar fields is not being “wasted” – in fact, it’s being enriched, regrowing organic matter, improving water filtration, providing habitat for the myriad of critters at the bottom of the food chain who get crushed in the normal course of agricultural production.

New research about the environmental significance of fallow lands in the Conservation Reserve Program (CRP), which pays farmers to leave soils fallow, underlines the point. The beauty of a solar farm is that it generates actual revenue, not only for the farmer, but for the local communities, in addition to providing clean, no carbon energy and a solution to the existential threat to this – and the next 100 – generations.

Civil Eats:

The Conservation Reserve Program (CRP)—a federal program that pays farmers to stop farming on low-quality pieces of their land through 10–15 year contracts—may be one of the most cost-effective ways to improve air quality, according to a new study. While the program’s benefits to habitat, soil, and water quality have been documented throughout the program, this study, published in the journal GeoHealth, is the first to quantify its life-saving air quality benefits.

The study found that areas with more acres of land set aside through CRP had lower levels of fine particulate matter. Using data from 2,300 counties, the researchers cross-referenced national public health data from 2001–2016 with each county’s percentage of arable land enrolled in CRP.

Fine particulate matter, or PM2.5, refers to particles no more than 2.5 micrometers in diameter. The particles are small enough to cause inflammation that leads to asthma, heart and respiratory diseases, and several cancers. This hazy cocktail often consists of dust, fossil fuel emissions, and the volatile organic compounds applied to farmlands. Ammonia from fertilizers, for example, breaks down to form fine particulate compounds. And when tractors and other heavy machinery till the soil it reduces plant cover, increasing windblown dust. Droughts also exacerbate PM2.5 levels. But the researchers found that areas with more CRP acreage also saw fewer deaths—“and many billions of dollars saved via those prevented deaths,” the study reads.

In 2008, when CRP acreage was 35 million acres, the authors estimate there were 1,300 fewer deaths than would have occurred if all the land had been farmed. Placing the value of a statistical life at $7 million (a bit less than the Environmental Protection Agency’s (EPA) recommendation), CRP saved roughly $9.5 billion.

National Science Foundation:

In a discovery that has repercussions for everything from domestic agricultural policy to global food security and plans to mitigate climate change, researchers at the University of Massachusetts have found that the rate of soil erosion in the midwestern U.S. is 10 to 1,000 times greater than pre-agricultural erosion rates. 

The 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.

The U.S. National Science Foundation-supported 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.

“We went to 14 small patches of remnant native prairie that still exist in Iowa, Minnesota, South Dakota, Nebraska and Kansas, and used a hand auger to collect deep soil cores, in material that dates back to the last ice age,” says Isaac Larsen, a geoscientist at the University of Massachusetts Amherst and the paper’s senior author. “We brought this soil back to our lab, sifted it to isolate individual sand grains, removed everything that wasn’t quartz, and then ran these few spoonfuls through a chemical purification process to separate out the 10Be — which was just enough to fit on the head of a pin.”

Not only is topsoil crucial for U.S. agriculture — the annual cost of diminished agricultural productivity and environmental degradation due to erosion is estimated at tens of billion dollars each year — and worldwide food security, but climate mitigation plans that rely on storing carbon in the soil. “The key is to reduce our current erosion rates to natural levels,” says Larsen.

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4 Responses to “More Reasons to Save Soil with Solar”

  1. Anthony O'Brien Says:

    You can still have grazing animals where there are solar panels. So the area is not lost to farming even while the panels are up. Lost to mechanised farming practices perhaps.

    • greenman3610 Says:

      absolutely true but still very much experimental. We are looking at a big solar farm in a nearby county that might be the first to have a major portion in sheep grazing, but it’s getting heavy opposition, by people who don’t give a damn about sheep, or soil, or anything else other than their paranoid ideations, so we’ll have to see.

  2. rhymeswithgoalie Says:

    There’s a lot of flexibility when it comes to solar power. It can displace farmland for later use, it can share with agriculture, it can shade the poor damn livestock out in the treeless fields of SW Louisiana, it can cover your hot parking lots and garage roofs, and it can cover your canals to reduce evaporation and algal growth. It requires non-exotic construction machines to put up (no giant cranes), it requires low and simple maintenance in the field (hand tools!), it can be upgraded gradually over the years, arrays can be resized or shifted to other sites if there is a conflict with other land uses, etc.


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