World / Science & Health

Stopping soil erosion is a matter of urgency, otherwise starvation will follow, scientists warn

Thomson Reuters Foundation

The world’s food production is in jeopardy because the fertile layer of soil that people depend on to plant crops is being eroded by human activities, scientists said Wednesday.

Climate change is likely to make it worse even as demand from a growing population is soaring, they said.

Soil erosion happens naturally, but intensive agriculture, deforestation, mining and urban sprawl accelerate it and can reduce crop yields by up to 50 percent, according to the United Nations’ Food and Agriculture Organization.

The FAO also said the equivalent of a soccer field of soil is eroded every five seconds, and the planet is on a path that could lead to the degradation of more than 90 percent of all the Earth’s soils by 2050.

“We’re approaching a critical point at which we need to start acting on soil erosion or we are not going to be able to feed ourselves in the future,” said Lindsay Stringer, professor at England’s University of Leeds, on the sidelines of a three-day conference on soil erosion co-organized by the FAO.

Erosion degrades soil, making it less able to withstand stresses such as changes in rainfall and longer droughts, said Richard Cruse, professor at Iowa State University.

A repeat of weather conditions like those experienced in 2012, including drought and famine in the Horn of Africa and hurricanes in the United States, “could really cut our food supply in a way that we haven’t experienced,” he said.

Yet policymakers are too caught up in day-to-day issues to focus on soil erosion, he added. “They have to deal with poverty, health, roads, things that are of immediate effect. Soil erosion is long-term. It’s like sands through an hourglass. We know what’s happening, but we’ll worry about it tomorrow.”

It is not hopeless, said Stringer, whose research in Kenya found that using manure as fertilizer or growing more than one crop on the same plot of land are simple and inexpensive actions that improve both soil quality and crop yield.

However, other proven methods to reduce erosion, such as building terraces and engaging in agroforestry — planting trees on cropland — can be too expensive for farmers, she said.

Ownership of land is key here, Cruse said. “In my conversation with farmers, they tell me: ‘If I own my own land and I’m farming, conservation is an investment. If I have to use these practices on rented land, it’s a cost.’ “

Governments can give incentives to farmers through subsidies and other means, because good soil benefits the wider society, while things would worsen if nothing is done, said Jean Poesen from Belgium’s KU Leuven university.

“Ninety-five percent of our foods come from soil. Can you imagine how the food section of a supermarket would look like if we had no soils? There would be nothing on the shelves,” he said.

“Once the soil is gone . . . people end up with hard, bare rock, and nothing grows. Then you have to migrate or start a fight with your neighbors and conquer.”