“That’s an earthworm hut right there,” he said, pointing to a mound rising above the dark soil.
At night, the worms wriggle to the surface to feast, pulling remains of plants into the soil and decomposing them. “They do the tillage for me,” Larson said. “They put the crop residue in the soil where it belongs.”
The amount and condition of that residue is crucial, and much of it comes from rye, a cover crop Larson buys and plants but will never sell.
Rye is a time-release nitrogen sponge. As it grows, the rye sops up excess nitrogen before it escapes into the air or water. After the rye dies and decomposes, bacteria squeeze the nitrogen back into the soil, fertilizing later crops. Cover crops are also a magnet for microorganisms that process nitrogen into fertilizer, and they have other benefits, from preventing soil erosion to smothering weeds.
All this means Larson can apply less fertilizer, and less of his nitrogen will break down into compounds that contaminate water, attack the ozone layer, and heat the planet.
Larson tills his cropland into narrow strips instead of overturning entire fields, another measure that preserves nitrogen-storing rye residue on his fields. Strip-tilling also makes it possible to drive a tractor between the rows and inject precise amounts of liquid fertilizer into both sides of his crops instead of spraying it over the entire field.
Larson said his corn and soybean yields increased as he cut back on fertilizer. Tests of the water running off his cropland, meanwhile, suggest the amount of nitrate in it is low.
“It makes sense socially and economically,” he said.
But only a small share of farmers plant cover crops and regularly use tillage practices that can reduce the environmental effects of fertilizers, though that count is rising with some crops in certain regions.
The USDA has increased spending to set aside farmland for conservation and on programs to train and equip farmers for practices that reduce nitrogen pollution.
Still, long-lasting prairies and grasslands, which have deep roots that can suck up excess nitrogen from soil and water, are disappearing. At the same time, following market signals and federal subsidies, American farmers grew fewer acres of small grains like barley, oats, rice, and sorghum and more fields of fertilizer-hungry corn, which has a shorter lifespan and shallower roots.
As climate change brings more weather extremes, it’s likely that improved soil and fertilizer management techniques will have even less of an effect for many regions in the future, said Matt Liebman, a professor and chair of the sustainable agriculture program at Iowa State University.
Solving the problem, he said, requires rethinking not only how but what America farms.
“Ohio, Indiana, and Illinois are a trainwreck this year because of the rain,” he said in the summer of 2019. The current system of rotating between corn and soybeans, he said, “is not going to cut it.”
‘Every farm is a chemical factory’
At the dawn of the 20th century, entrepreneurs and governments raced to find an industrial process to turn atmospheric nitrogen into commercial compounds. The Nobel Prize-winning method that prevailed — still the principal process used to create more than 100 million tons of the element for fertilizer in 2018 — is a chemical reaction of nitrogen and hydrogen that produces not only fertilizers but also explosive weapons.
This dual purpose meant nitrogen synthesis was synonymous with national security. The U.S. government subsidized nitrogen producers under “arms-to-farms” initiatives that supplied munitions for wars and fertilizers during peacetime.
In 1928, then-Agriculture Secretary William M. Jardine wrote that “every farm is a chemical factory.” As the USDA promoted fertilizer-intensive agriculture, fertilizer use and crop yields boomed, especially in the latter part of the 20th century. Less than half of U.S. cornfields were fertilized with commercial nitrogen in 1950. Today, 99 percent of cornfields are.
As invested as the federal government was in creating the fertilizer industry, it has taken a back seat in managing its downsides — even as they worsen.
Stricter federal regulations on greenhouse gas look unlikely in the short term. Regardless, CF Industries Holdings, the largest U.S. nitrogen fertilizer producer, identified that as a “significant” business risk in financial filings. Mosaic, another big producer, identified similar risks and said the multistate effort to limit agricultural runoff and reduce the Gulf dead zone could hurt its business.
The bigger issue? The U.S. market could be maxed out. Fertilizer companies are looking to other, even more lightly regulated markets where they could see the same explosive growth they once had here. In filings and remarks to investors, industry giants point to profitable, long-term trends for fertilizer sales: population growth, higher meat consumption, and more biofuels — particularly in developing countries.
“The U.S., Europe, and Brazil are already using enough nitrogen,” said Seth Goldstein, an analyst with investment research firm Morningstar. “Africa will likely be the area of largest nitrogen demand growth going forward.”
The potential for sharply expanding global fertilizer use — and more harmful climate effects — has scientists sounding alarms.
In October, more than 200 scientists signed an open letter that urged world leaders to act immediately to reduce nitrogen pollution. It’s threatening the health of humans, animals, and plants, they said, but isn’t prioritized in environmental policies focused on carbon dioxide. Letter author Mark Sutton, a U.K. environmental scientist and former chair of the International Nitrogen Initiative, said there’s no way to meet the goals laid out in the Paris Climate Agreement without addressing nitrogen pollution.
“If we want to beat climate change, air pollution, water pollution, biodiversity loss, soil degradation and stratospheric ozone depletion, then a new focus on nitrogen will be vital,” Sutton wrote in the letter to the secretary-general of the United Nations. “The present environmental crisis is much more than a carbon problem.”
International limits have led to steep reductions of other dual-impact gases, but nitrous oxide emissions continue to increase.
The Montreal Protocol — signed by every country in 1987 and regarded as the most effective international environmental agreement — phased out the production and use of chlorofluorocarbons and other ozone-depleting substances, but it didn’t set limits on nitrous oxide.
That’s now the planet’s dominant ozone-depleting gas.
Later treaties, including the 1997 Kyoto Protocol and the 2016 Paris Agreement, called for nitrous oxide reductions. The U.S. did not join the former and is in the process of dropping out of the latter.
The Montreal treaty worked “because the sources were industrial. Few actors, simple system,” Sutton said. By comparison, he said, cutting nitrous oxide “means transformation of society.”
So far, he said, the largest reductions to fertilizer side effects are in places such as Denmark and the Netherlands — countries with enforceable rules.
“The scientists I speak to say they believe that this would never have happened unless they’d have had mandatory action,” Sutton said. “There clearly has to be a role for regulation if countries are serious about making progress.”
Zach Goldstein contributed to this story.
This story was published in partnership between Grist, the Center for Public Integrity — a nonprofit, nonpartisan newsroom that investigates betrayals of public trust — and The World, a radio program that crosses borders and time zones to bring home the stories that matter.
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Joe Wertz Center for Public Integrity | Radio Free (2020-01-22T13:34:56+00:00) Fertilizer is a major pollutant. Why doesn’t the government regulate it as one?. Retrieved from https://www.radiofree.org/2020/01/22/fertilizer-is-a-major-pollutant-why-doesnt-the-government-regulate-it-as-one/
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