Farmers can save the world’s soils and feed humanity for more than 10,000 years if they embrace soil conservation practices, suggests recent research from Lancaster University in the United Kingdom, Chang’an University in China, and KU Leuven in Belgium.
“Urgent action worldwide is needed to prevent the thinning of soil profiles and the subsequent collapse of…food production,” Dan Evans, first author on the paper and a research fellow at Cranfield University in the U.K., tells Food Tank. “By adopting appropriate soil conservation methods, we can slow rates of erosion and, in some cases, cause soils to grow. This is fundamental if we are to protect and enhance our soils and sustain the food system for future generations.”
Soil erosion is outpacing soil formation, impairing the earth’s storage of vital nutrients, water, and carbon. The U.N. Food and Agriculture Organization (FAO) has warned that the planet has less than 60 harvests left. Evans’ team wanted to verify this forecast.
The researchers analyzed more than 10,000 total years of soil erosion rates from over 250 sites in dozens of countries around the globe. The plots were either conventionally farmed or managed using soil conservation strategies, such as reduced tilling. The investigators then married this data with soil building information to gauge each location’s soil lifespan. That’s the time it would take to erode 30 centimeters of topsoil, which contains a lot of nutrients and organic matter critical to agriculture.
The results revealed that more than 90 percent of conventionally farmed soils were thinning. Sixteen percent had lifespans shorter than a century. The findings “demonstrate the pervasiveness, magnitude, and severity of the threat posed by soil erosion to soil sustainability and to the future of the food system,” Evans tells Food Tank.
Even so, he calls the FAO’s prediction “alarmist,” pointing out that over three-quarters of the study areas had lifespans greater than 60 years. He says that the FAO’s projection doesn’t consider differences in land management and other local factors across the world.
The researchers also found that only 7 percent of soils under conservation management had such concerning lifespans, and almost half surpassed 5,000 years.
“Converting arable land to forest was…the best way to lengthen soil lifespans,” he says.
Cover cropping was also very effective. Plowing along contours and terracing steep slopes to cultivate the resulting steplike platforms helped as well, he says.
Conservation techniques can indeed secure the soil, according to Mahdi Al-Kaisi, soil management and environment professor at Iowa State University. He stresses the need for “a national policy that supports such efforts through the Farm Bill” in the United States.
Since the success of soil conservation measures varies from landscape to landscape, Evans adds, land managers, officials, and scientists should identify, implement, and assess the right solutions by locality, too.
“Working in partnership is essential if we are to prevent the collapse of our soil resources and their valuable ecosystem services,” he tells Food Tank.
Photo courtesy of Dan Evans.
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