When François Peaucellier talks about soil, he sounds like a sommelier. "It's full of little leaves,” says the French farmer, holding up a clod from his field. “The earth is supple and beautiful. There is a surface life that is superb."

Peaucellier, who grows cereals and vegetables on a 200-hectare farm in the Hauts-de-France region north of Paris, is part of small but growing movement of farmers who are cutting back on pesticides not so much out of concerns for human health — but because they worry about what it does to the soil.

Public attention on the risk of pesticides has focused on what chemicals like glyphosate do to human health. A U.S. federal jury last week ordered Germany's Bayer to pay more than $80 million to a man who claimed his cancer was caused by exposure to the weedkiller.

But farmers like Peaucellier say the weedkiller’s impact on soil health has been overlooked, and represents a serious threat to Europe’s long-term food security. Soil experts, academics and scientific studies are also establishing clear links between the use of substances such as glyphosate with drops in soil fertility and the collapse of microbe ecosystems essential to healthy soil.

“Soil, like any resource, must be respected and protected" — Graeme Taylor, director of public affairs for the European Crop Protection Association

With more than a third of the world's land already degraded by erosion, compaction and chemical pollution, according to the U.N.'s Food and Agricultural Organization, thousands of farmers in countries like France are starting to embrace new methods.

Peaucellier, 30, no longer measures success just by the bounty of his crops, he says, but by the number of worms he finds living in the soil beneath them. "Look at the rapeseed plants. Normally the plants should be twice as high as that,” he says, gazing at his neighbor’s fields.

He pierces his own land with a yellow spade. The soil is marbled with healthy decomposing roots, crawling lice and squirming earthworms. "These animals do so much more work than any fertilizer will do,” he says. “But you need one, two, three years to bring back the life.”

Disappearing earthworms

The European Union currently has no legal limit for the amount of glyphosate permitted in European soil, according to Vera Silva, a researcher for the soil physics and land management group at Wageningen University in the Netherlands.

Silva has carried out extensive research into the prevalence of pesticide residues found in European soils. Though glyphosate can kill specific fungi and bacteria that plants need to suck up nutrients, "the effects of such a change are not completely understood yet," she says.

Silva and other researchers at Wageningen University raised concerns about pesticide residues in a 2015 study, which looked at more than 300 samples of agricultural topsoil from across the EU.

They found that four out of five samples contained at least one residue, and nearly three in five contained mixtures of chemicals. Little is known about the effects of mixtures. “The combined effects of residue mixtures need to be assessed,” the study recommended.

Another study from 2015 carried out by researchers from the University of Natural Resources and Life Sciences in Vienna also showed that casting activity of earthworms had nearly disappeared from the surface of farmland within three weeks of glyphosate application.

Earthworms redistribute organic material in soil and are essential for soil fertility.

The animals’ reproductive activity fell by more than half, according to the same study. "These sizeable herbicide-induced impacts on agroecosystems are particularly worrisome because these herbicides have been globally used for decades," the study found.

Beyond worms, the chemical appears to damage microbes that aid in plant decay, mineralization, and soil’s vital carbon and nitrogen cycles. "Glyphosate can be present in some soil organisims,” says Silva. “As soon as these organisms are affected, soil functions might be impaired."

Weighing the benefits, risks

Nearly 500 active substances are approved for use in pesticides in the EU, and European farms buy 374,000 tons of pesticides annually, according to Eurostat, the EU's statistical agency. Globally, 3 million tons of pesticides are used each year, generating about $40 billion in revenue.

Bayer, the world's largest producer of glyphosate, says that "precise application of glyphosate-based herbicides can allow farmers to leave the soil intact," reducing tilling practices that release greenhouse gases and contribute to erosion.

"The idea is to say to politicians 'help us to finance our cover crops rather than buying enormous machines that are useless’” — François Peaucellier, French Farmer

Pesticides companies also point out that users of pesticides should follow rules in the EU's Sustainable Use Directive, which requires farmers to be trained in their use. The directive also mandates that all chemical equipment be inspected, prohibits aerial spraying and limits pesticide use in sensitive areas.

“Soil, like any resource, must be respected and protected," says Graeme Taylor, director of public affairs for the European Crop Protection Association, a lobby representing the pesticide industry. "The strong implementation of the Sustainable Use Directive is crucial in this respect.”

Taylor added that EU pesticide laws insist that pesticides undergo a soil risk assessment in which an acceptable concentration is defined.

Even glyphosate-skeptics like Peaucellier acknowledge that farming without pesticides is difficult. Peaucellier still uses small amounts of glyphosate on his fields. To reduce his use further, he is experimenting with new strategies like conservation agriculture, a system that promotes permanent soil cover, no tillage and regular crop rotation as a way of improving biodiversity.

Peaucellier’s new farming practices go like this. Rather than leaving land fallow after a harvest, he immediately reseeds with a “cover crop” that’s left to wilt. He crushes the cover plants with a roller, so they lie against the ground, helping prevent weeds. Soon they decompose and replenish the soil with nutrients.

Last year Peaucellier began field tests comparing different cover crops and glyphosate doses on 30 strips of his own farmland. At the end of May he’ll review the test plots with experts from the French National Institute for Agricultural Research, and evaluate the results.

Peaucellier is one of 5,000 farmers in France to have adopted conservation agriculture techniques, he said. On Thursday he is scheduled to travel to the National Assembly in Paris, to argue for conservation agriculture to be specifically subsidized as part of the EU's €59-billion-per-year Common Agricultural Policy. The national farming plan predominantly focuses on conventional farming methods.

"The idea is to say to politicians 'help us to finance our cover crops rather than buying enormous machines that are useless,’” he says. “They don't understand that planting a seed can be useful to cover the soil, nourish the soil and avoid that carbon is released into the atmosphere."

To illustrate his point, Peaucellier crosses the road to his neighbor’s field and drives his shovel into the ground. The earth is hard, compact and resists his attempt to break it up. Underneath, the ground is hard, with no evidence of underground life.

He points to a large crack — evidence of erosion. Pesticide residues had run off and contaminated a stream further down the valley, he says. "When it's sprayed on ... the degradation of the earth is much quicker," he says.

“There's a real problem when we say we have to put in more to have more,” he says.

This article is part of a special report on soil degradation in Europe.

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