The world's topsoil is vanishing. Can we save it?

In now-famous remarks commemorating the first-ever World Soil Day — created in 2014 to raise global awareness about the importance of healthy soil — Maria-Helena Semedo, Deputy- Director General for the Food and Agriculture Organization of the United Nations, said it takes 1,000 years to generate just three centimeters of topsoil, the nutrient-rich, uppermost layer of soil that contains the organic matter, minerals, air, water and microorganisms necessary to support crop growth. Given current rates of soil degradation, Semedo predicted, 100% of the world's topsoil could be gone within 60 years. That means farmers could have fewer than 50 harvests left in their fields.

"More topsoil in America has likely been lost in the last 100 years than in the entirety of history prior,” says Jordan Rubin, owner and operator of Heal the Planet Farm, which spans nearly 4,000 acres across two locations in Missouri and Tennessee. Specializing in mushrooms, botanicals and animal-based ingredients, it’s one of only six farms in the U.S. to receive the "Regenerative Organic Certified” designation from the Regenerative Organic Alliance, whose goal is promoting agriculture practices that rehabilitate depleted soils.

While soil health varies across regions — he’s seen areas in middle Tennessee where there’s “no discernible” topsoil and areas in rain-rich Costa Rica where there’s "more topsoil than you can measure.” Rubin says the topsoil in most places is "probably … inches instead of feet.”

The long-term degradation of farmable soil could have a disastrous impact on agricultural production, scientists warn.

"As a society, we depend on agriculture for our whole existence,” says ecosystem ecologist Steven D. Allison, Professor, Ecology & Evolutionary Biology at theCharlie Dunlop School of Biological Sciences at the University of California, Irvine. "And agriculture depends on soil.”

Spoiled soil

The biggest threat to soil is industrial farming, argues Rubin, who says the heart of large-scale food production is monocropping, the practice of growing a single crop — usually corn, soybeans or wheat — repeatedly on the same land.

"Large, conglomerate farms are typified by one or two crops a year, leaving the ground wide open to get baked in the sun, which can lead to soil erosion and microbial loss,” says Rubin, who also says a common feature of monocropping is fallowing, where farmers leave arable land unplanted for one or more growing cycles. That leaves land exposed, making it easy for wind and rain to wash topsoil away during extreme weather events, which are increasing in frequency and severity due to climate change.

While monocropping can increase short-term yields, it can create a vicious cycle because it hurts soil in the long term by depleting nutrients, reducing its ability to hold water, and increasing its vulnerability to pests and disease, which increases farmers’ dependence on fertilizers and pesticides that further destroy the soil microbiome.

Plus, monocropping often goes hand in hand with tillage. "Tilling breaks up any remaining microbiological colonies of bacteria and fungi, which are the workhorses of the soil that create nutrients for plants,” Rubin says.

Ancient ways to the rescue

The good news: Soil degradation "absolutely is a solvable problem,” according to Allison. "We have methods that … have been around for a long time that we know improve soil quality,” he says.

Those methods in modernity are known collectively as "regenerative agriculture,” says Eric S. Bendfeldt, an Extension Specialist and Associate Director of the Center for Food Systems and Community Transformations at Virginia Tech. As a partner of 4 the Soil, he supports using cover crops to prevent erosion; reducing physical and chemical soil disturbance, including tilling, pesticides and fertilizers; and building healthy soil ecosystems through crop diversity, crop rotation and livestock grazing.

"These practices don’t just protect topsoil; they can help regenerate and rebuild it,” Bendfeldt says.

An army of veritable soil whisperers is leading the charge to implement and scale regenerative farming practices. Among them is Rubin, who rotates his crops; sows seeds without tillage; uses cover crops like grasses and legumes to protect fields that might otherwise lie fallow; and incorporates livestock like water buffalo, exotic cattle, ducks, goats and sheep, whose grazing and manure naturally enrich soil without synthetic fertilizers.

Another way to naturally enrich soil is spreading compost. Currently, as much as half of all commercially processed compost in the U.S. is used on farms, says Linda Norris-Waldt, executive director of the U.S. Composting Council. Made of decomposed organic matter, including food scraps, farm residue and yard waste, compost reduces erosion, increases soil organic matter, improves water retention and suppresses plant disease, she says.

Compost also fuels beneficial soil microorganisms, a growing front in the fight for healthier soil, according to Allison, who says agribusiness companies might soon be able to mass-produce soil-enriching microbes that farmers can spread on fields.

"There’s a very rich and diverse microbiome that lives within crop soils and around the roots of plants, and the vast majority of these microbes are helpful. They’re doing important, beneficial jobs like improving plant growth and keeping the soil porous so that it doesn’t erode,” Allison says. "We’re learning more and more about these microbial helpers in the soil, and that’s a really exciting development because now we have the opportunity to mine them.”

Although the technology to "mine” microbes is still developing, other technologies already are helping soil whisperers accomplish their mission. Inventor Michael Smith, for example, has created a closed-loop system called the Earth Power Lodge that uses solar energy to turn wood chips into biochar, a carbon-rich soil amendment that can has proven to regenerate depleted soils.

A mix of innovative solutions

Corn and soybean producer Robert Waring of Dunnsville, Virginia, meanwhile, is using commercial satellite imagery alongside regenerative farming to quantify the biomass of cover crops in his fields and reduce inputs.

“Inorganic fertilizers are salts, and these salts have a degradation effect on the biology in the soil. If we can quantify biomass in the fields using satellite imagery, then we can avoid blanket applications of phosphorus or potassium and apply them only where we need them,” says Waring, who foresees using drones for similar purposes.

While farmers such as Waring and Rubin are doing their part, achieving healthy soil at scale requires other producers to follow suit, according to Bendfeldt by supporting local and regional farmers who are practicing regenerative agriculture, Bendfeldt says consumers can create demand to change the food system from the ground up.

"All of us need to do our part,” he says. "Each of us needs to open our eyes and become more curious about what’s happening … in the soil beneath our feet.”