Iowa's legendary soil, the bedrock of its economy, is losing its richness, new research shows - Des Moines Register

Exclusive: Iowa's legendary soil losing its richness, new data shows

Iowa's legendary soil, the bedrock of its economy, is losing its richness, new research shows

Iowa is whittling away at one of its most valuable assets: its rich, black soil.

Wind and water erosion are familiar culprits. But new modeling that adds factors including tillage and an undisrupted rotation of nutrient-hungry corn and soybeans shows farmers lose a staggering 12 million tons of their soil's organic carbon each year, says Jerry Hatfield, a retired U.S. Department of Agriculture scientist.

“This just doesn’t impact rural Iowa,” said Hatfield, pointing to Iowa’s role in feeding the U.S. and other nations. “It impacts everybody.”

Over four generations of farming, Iowans have wiped out at least half of the state’s original bank of 96 billion tons of soil organic carbon, according to data obtained exclusively by the Des Moines Register. This finding comes from a national team, led by Hatfield, that is working to quantify, field by field, carbon loss across Iowa and the Midwest.

The impact of Iowa's reduced soil organic carbon is broad: Growers must rely more on fertilizers and chemicals to get good yields, eating into farm profits, Hatfield said. Reduced soil organic carbon also decreases the soil's ability to absorb and hold onto water — an issue that can lead to downstream flooding, soil erosion and fertilizer runoff that can pollute the state’s rivers, streams and lakes, endangering drinking water supplies and degrading aquatic environments.

Soil health also is vital to Iowa's economy. The state’s legendary farmland, selling for up to $30,000 an acre, is conservatively valued at $278 billion. And agriculture powers 10% of the state's $179 billion annual economy, supporting thousands of jobs in farm equipment manufacturing, crop insurance, raising livestock, renewable fuel production, and other related industries, an Iowa State University study shows.

The attempt to better quantify Iowa’s soil carbon loss comes as the Biden administration is investing at least $20 billion to reduce farming’s impact on climate change, part of an overall $2 trillion effort to slash U.S. greenhouse gas emissions by half over seven years.

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The challenge is significant in Iowa, where agriculture’s share of greenhouse gas emissions is about three times farming's impact nationally, 2021 state and federal data shows. Contributing to agricultural emissions: fertilizer production, manure from cattle, pigs and chickens, and the soil itself, as crop residue breaks down.

Mitchell Hora, a southeast Iowa agriculture consultant, believes Iowa farmers can boost their bottom lines if they cut greenhouse gas emissions from their operations.

He estimates the low-carbon grain his family produces, using carbon-building practices such as reduced tillage and fertilizer use, planting cover crops and diversifying their crops, is worth hundreds of dollars per acre to companies that want to use the greener ingredient in ethanol, biodiesel, breakfast cereal, beer, pork, beef and other products.

“I just see this as a huge opportunity to decarbonize ag, decarbonize transportation and decarbonize energy,” Hora said. At the same time, “it improves family-farm profitability and rural vitality, while also building soil health and improving water quality.”

Without adopting conservation practices like the Horas have done, farmers could face disaster, eventually burning through Iowa’s soil carbon supply, said Michael McNeill, a northwest Iowa ag consultant who works with farmers to transition to organic farming.

“We can turn the beautiful soil we have here into a desert,” McNeill said. “Man has done that in some places in the world. And it can happen here.”

A hard rain exposes hard truths

Ray Gaesser stopped tilling his rolling southwest Iowa fields — a practice often referred to as no-till — about three decades ago. And he started using cover crops about a decade ago, now planting them on two-thirds of his family’s 5,000 acres.

Growing cover crops after harvest adds roots in the soil through the next spring, feeding bugs, microbes and fungi that also devour leftover corn and soybean roots, stems, husks and leaves. And no-till significantly reduces the carbon dioxide that leaves the ground, dissipating into the atmosphere, through conventional tillage.

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Gaesser said a massive rain drove him and his son, Chris, who farms with him, to begin using cereal rye cover crops.

“We thought we were doing a terrific job, with our no-till, building organic matter, and our terraces and our grassed waterways, protecting the soil” from erosion, he said. “But we watched a 4-inch rain in an hour lift all the residue we had accumulated … and floated it all away."

The large, intense rains continued annually over seven years, Gaesser said. “We decided we had to do something different,” he said.

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Iowa has been pummeled with extreme weather over the past five years. In that period, the state has been hit with two dozen extreme weather events with damages that exceed $1 billion, including tornadoes in 2022 that killed seven Iowans and the 2020 derecho that caused $13 billion in damage across eight states, wiping out homes, businesses and crops, according to NOAA’s National Centers for Environmental Information.

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And over the past three years, Iowa has been in the grips of the longest drought in two decades. Extreme drought now encompasses a quarter of the state, the U.S. Drought Monitor shows. Less than half of Iowa's corn and soybeans are now considered in good or excellent condition, USDA data shows.

Increases in intense rainstorms, windstorms, drought and other extreme weather are expected to continue as the climate warms, scientists say.

One of the toughest challenges Gaesser said his family has faced in rebuilding their soil is diversifying their corn and soybean rotation. After years of work, his son and daughter-in-law, Shannon, send the cereal rye they harvest from about 200 acres to Revelton Distilling Co., a maker of whiskey and gin in Osceola, about 50 miles away. The family uses the remaining rye to cover its own acres and to sell to neighbors.

Gaesser said his family’s efforts have helped their farm survive extreme weather. "We see real advantages in our ability to grow a crop, even under adverse conditions — both too wet and too dry," he said.

Shifting toward more soil-healthy and environmentally friendly practices can be difficult for farmers, he said, “even though it’s better financially," with lower expenditures for equipment and fuel.

"It’s a risk that some are hesitant to take on,” said Gaesser, adding that he's not experienced yield losses with the less carbon-intensive practices.

For Gaesser, the work that the conversion involved is an investment.

“We want our farm to be there for the next generation,” he said.

Devising 'sophisticated models' to better measure what's at stake

The Biden administration is investing heavily in reducing agriculture’s greenhouse gas emissions, with about $19.5 billion going to the nation's biggest conservation programs over five years.

The USDA also said it would pour $3.1 billion into about 140 projects that are expected to cut greenhouse gas emissions from crops and livestock, efforts that are bringing together farm groups, agribusinesses, carbon companies and environmental groups.

Iowa could share about $1 billion along with neighbor states through multistate initiatives that focus heavily on cover crop adoption, fertilizer management and tillage reduction, USDA data shows.

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Farmers are expected to sequester 60 million tons of carbon dioxide through the federal partnership projects. With critics questioning whether farmers will reach the projection, the USDA said in July it would spend $300 million to better quantify the work the nation’s farmers can accomplish to sequester and build carbon ― work Hatfield's research aims to advance.

“If you get a producer that signs up to reduce their carbon, how do you know they reached the level of reduction that you’re paying them for?” said Hatfield. He's part of a USDA partnership project in Kansas, Colorado, Montana and other western states that will use so-called "flux towers" ― micrometeorological stations ― to measure the carbon that's sequestered in fields where farmers add camelina, an oilseed cover crop, to the rotation.

Scientists are quantifying carbon sequestration by measuring the exchange of carbon and water in the soil: Plants give up water to get carbon dioxide from the air.

The team uses modeling to compare the land to fallow fields — with no cover crops to protect the soil after harvest — adding in factors such as fertilizer and equipment use, atmospheric changes in weather, crop rotation and plant development.

"These are sophisticated models that will enable us to measure these factors on a day-by-day basis," Hatfield said, adding that the team also will intensively test the soil for carbon to assess the model's results. This study, conducted over five years, is expected to provide robust data, quantifying how soil carbon changes when crop rotations change.

Farmers especially need long-term data so they can have more confidence in the practices they’re using, since some conservation practices need time for benefits to emerge, he said.

Addressing 'unsustainably expensive' climate risks

The work also could aid in limiting the impact of climate change on agriculture. Relying on crop insurance and disaster aid alone is "unsustainably expensive" for farmers and taxpayers, the Environmental Working Group said this month, releasing a report showing U.S. farmers received a record $19.1 billion in payouts to cover crop losses last year.

“Our analysis showed that the costs of the Crop Insurance Program have spiraled, in large part because of increasingly extreme weather tied to the climate emergency,” said Anne Schechinger, the Washington, D.C., group's Midwest director.

Iowa, the top U.S. corn producer, ranked fourth nationally for its crop loss payouts over 22 years at $10.2 billion, the report showed. Iowa farm loss payments have doubled over that time to $316.4 million last year. Farmers pay about 40% of the crop insurance costs, with the USDA covering roughly 60%.

“Without meaningful reform, the federal crop insurance program will become unsustainably expensive for both farmers and taxpayers,” said Schechinger, whose group is pushing for crop insurance changes, including encouraging conservation adoption that makes farms more resilient to extreme weather.

Sean McMahon, who leads an Iowa agriculture-based conservation effort, would like more attention and increased incentives for farmers who improve their use of nitrogen fertilizer, a large source of harmful nitrous oxide and methane greenhouse gases.

Farming is Iowa's largest source of the two harmful greenhouse gases, contributing 94% of the state’s nitrous oxide emissions and 82% of the methane, the Iowa DNR greenhouse gas inventory shows. Nitrous oxide is considered 265 times more warming than carbon dioxide, according to the U.S. Environmental Protection Agency, and methane is nearly 30 times more potent.

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It's the “lowest hanging fruit by far in Iowa,” sad McMahon, executive director of the Iowa Agriculture Water Alliance, a group formed by the Iowa Corn Growers, Iowa Soybean Association and Iowa Pork Producers. It's “what every farmer wants to do” to save money on production costs, he said.

Farmers have found building soil organic matter can cut how much fertilizer they need to raise their crops. It also can increase their "fertilizer efficiency," Hatfield said, meaning they can get greater yields without increasing fertilizer use.

McMahon said Iowa farmers "are among the most efficient in the world" at using fertilizers, "But there's room for improvement." For example, farmers can shift part or all of their nitrogen fertilizer application from the fall to the spring, when a newly planted crop will use the nutrients, making it less likely the fertilizer will run off or be lost to the atmosphere through volatilization.

While building soil organic carbon is important, McMahon said, it's also fragile, undone with tillage equipment. "You could lose that carbon that's been sequestered for many years," he said.

Cutting nitrous oxide and methane emissions are “considered an immediate, permanent reduction in greenhouse gas emissions,” he said.

That’s good news for farming, which is expected to account for 40% of Iowa greenhouse gas emissions by 2030, the Iowa DNR report projects.

If soil is losing fertility, why are yields climbing?

Farmers often ask Hatfield why their corn and soybean yields are improving if their soil organic matter is dwindling.

At 200 bushels per acre, Iowa's average corn yields last year were 45% higher than 25 years earlier, 72% higher than 50 years ago and about 4.5 times the yields from 100 years ago, USDA data shows.

Soybean yields have climbed as well: Last year, Iowa farmers averaged 58.5 bushels per acre, 27% higher than 1997; 63% higher than in 1972; and nearly five times yields in 1924, when the USDA began collecting soybean yield data.

Hatfield tells farmers that yield losses are being offset by improved seed genetics and crop management, with technology that allows farmers to better plant, fertilize and grow their crops as well as protect them from disease, insects and weed pressure.

But farmers can look across their fields and see the impact of soil carbon loss. Their yield monitors will show where corn yields lag, for example, dropping from 300 bushels an acre to 150 or less.

With reduced soil fertility, farmers lean on fertilizers to boost yields, Hatfield said.

"We've made our soils dependent upon external inputs," Hatfield said. "And when we make them dependent on external inputs, we have increased risk of things leaking out of the system because the soil doesn't have the capacity to hold onto them."

Iowa farmers rely on underground drainage tiles to help remove excess water from fields, improving growing conditions and yields. But critics say they also act as a conduit for fertilizers to move from fields into Iowa's waterways. Removing nitrates and harmful bacteria and toxins from source water adds costs to cities and towns that rely on rivers and lakes for drinking water.

Farmers could one day ask themselves: "Where did our production capacity go? Why are we no longer able to capture the benefits of improved hybrids?" Hatfield said, adding that no-till, strip-till, cover crops and other conservation practices can rebuild soil organic matter.

With strip-till, farmers use a machine that tills a small strip where the seeds are planted, minimally disturbing the soil.

"We can restore soils," Hatfield said, adding that farmers can begin to see soil health improvements in a year or two years and rebuild a farm's organic carbon within a decade.

"Farmers should ask themselves what they need to do to improve the capacity of their land to produce a crop and buffer against some of the extreme weather that we’ve seen and will continue to see," he said.