The world needs topsoil to grow 95% of its food – but it’s rapidly disappearing

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Susan Cosier

Without efforts to rebuild soil health, we could lose our ability to grow enough nutritious food to feed the planet’s population

 The Sarigua desert, west of Panama City, Panama, seen after overgrazing by livestock and the loss of topsoil through erosion. Photograph: Tomas Munita/AP

The world grows 95% of its food in the uppermost layer of soil, making topsoil one of the most important components of our food system. But thanks to conventional farming practices, nearly half of the most productive soil has disappeared in the world in the last 150 years, threatening crop yields and contributing to nutrient pollution, dead zones and erosion. In the US alone, soil on cropland is eroding 10 times faster than it can be replenished.

If we continue to degrade the soil at the rate we are now, the world could run out of topsoil in about 60 years, according to Maria-Helena Semedo of the UN’s Food and Agriculture Organization. Without topsoil, the earth’s ability to filter water, absorb carbon, and feed people plunges. Not only that, but the food we do grow will probably be lower in vital nutrients.

The modern combination of intensive tilling, lack of cover crops, synthetic fertilizers and pesticide use has left farmland stripped of the nutrients, minerals and microbes that support healthy plant life. But some farmers are attempting to buck the trend and save their lands along with their livelihoods.

“We never want to see our soil unless we go looking for it,” says Keith Berns, a Nebraska farmer whose land hasn’t seen a plow in three decades.

He and his brother, Brian, began the practice of no-till on their 2,100-acre corn and soybean farm when they learned it could increase the carbon, nutrients and water available in the soil. Their farm is in a particularly dry area of the country, and keeping moisture on their land is a top priority. For every 1% increase of carbon, an acre of land can hold an additional 40,000 gallons of water.

Once they stopped tilling, the Berns family saw organic matter in the soil increase, which can have the added benefit of making foods grown in the soil more nutritious.

Organic matter, a section of soil that contains decomposing plant or animal tissue, serves as a reservoir of nutrients that microbes can feast upon while they provide nitrogen to growing plants and sequester carbon. The more organic matter, the more organisms the soil can support.