Rain fell at 4 inches an hour on Ray Gaesser’s southwest Iowa farm one spring day in 2013.
The Corning, Iowa, corn and soybean producer in the heart of continuous corn and ethanol country has used no-till since the 1970s, but the damage to his ground made him rethink his conservation plan.
“What we’ve done has been adequate for 20 years,” Gaesser said.
He needed more. Gaesser planted 200 acres of cover crops and expects to add 1,250 more next fall on his 6,000-acre operation. Iowa’s soil is washing away, yet experts tell DTN it is difficult to make a connection between erosion and the ethanol-fed-corn demand boom that has led to increased farm income and economic development in rural America.
The state’s erosion battles started long before the corn boom, said Richard Cruse, professor and director of the Iowa Water Center at Iowa State University and the Iowa Daily Erosion Project.
During the ethanol and export demand expansion, much of the state’s cropping change came from switching soybeans to continuous corn, Cruse said.
“This switch would not favor elevated soil erosion rates as soybeans are the most erosive crop grown in Iowa,” he said. “Corn produces much more above- and below-ground biomass than soybeans, giving better land protection than do soybeans.”
However, localized acres retired from the Conservation Reserve Program and brought into row-crop production would experience higher erosion rates, he said.
One way to keep track of what is happening is the development of the Iowa Daily Erosion Project, which is operated at Iowa State University. It includes a network of soil monitors placed throughout the state to record erosion rates on a daily basis. The monitors send real-time data to a central database, allowing soil erosion maps to be generated.
The erosion project shows an increase in regional erosion rates above the sustainable level of 5 tons per acre from 2007 to 2009 — during the heart of Iowa’s ethanol expansion.
Up to 5 tons per acre was considered a sustainable soil loss in the 1940s. The IDEP average estimates are corroborated by national estimates for Iowa erosion loss of around 5 tons.
EROSION MAY BE WORSE
However, the project’s monitors track just a fraction of soil erosion taking place across the entire state. Cruse said erosion may be worse than even project data detects because monitoring sites aren’t accounting for gully erosion. The monitoring sites cover just 6 million acres of the Iowa landscape, and those sites aren’t located in gullies.
“We’ve seen some significant gully erosion,” said Roger Wolf, director of environmental programs and services for the Iowa Soybean Association. “Conservation practices aren’t doing the job. It’s very visible after those extreme (rainfall) events. It is an ongoing management issue.”
Though the statewide average may be considered to be sustainable, the erosion project has found locally high erosion rates. In 2007, 440 townships recorded erosion rates of more than 5 tons, according to the IDEP. A township equals a 36-square-mile section of land.
During the floods of 2008, the number spiked to 606 townships. In 2009, the number hit 641 with more than 5 tons. That included 30 townships with rates above a staggering 50 tons.
From 2010 to 2013, however, project maps show a decline in the number of sites reporting average rates of 8 tons or higher — coinciding with drier Iowa conditions in 2011 and widespread drought in 2012.
Even before the ethanol/export boom, western and eastern Iowa experienced soil losses of 16 tons or higher in the late 1990s. Those areas remain trouble spots today.
Since the first renewable fuel standard in 2005, the number of Iowa ethanol plants has more than doubled from 18 to 40, according to the Iowa Renewable Fuels Association. Iowa is the nation’s largest ethanol and corn producer.
Iowa acres planted to corn expanded from about 12.8 million in 2005, according to the National Agricultural Statistics Service, to about 14 million in 2013. The state hit its highest corn acres planted at 14.2 million in 2007 and again in 2012.
NASS said 76 out of 99 Iowa counties recorded their maximum period of percentage of acres planted to continuous corn from 2005 onward.
CONSERVATION DECISIONS
All 3,000 of Gaesser’s corn acres feed ethanol. Yet the fuel boom has done little to sway his belief in the need for conservation. His 50-50 rotation pre-dates the Iowa ethanol expansion.
Higher farm income sparked by ethanol has allowed Gaesser to afford conservation. He said he’s not willing to trade short-term financial gain for long-term harm to the land. “For us in our soils here, no-till works really well,” Gaesser said.
“We quit ripping about 15 years ago. We could see yields improve. We don’t have to disk or chisel anymore, plus we’re keeping that soil where it needs to be. In the long-term you just can’t replace that.”
Wayne Fredericks, an Osage, Iowa, farmer who operates a corn/soybean farm in proximity to six ethanol plants at the Minnesota border in the northeast part of the state, said his brief move to continuous corn on some acres didn’t pay off financially. He turned away after seeing yields drop despite the use of strip-till.
“I’m a real numbers person,” Fredericks said. “We have a 10% advantage to rotating corn and soybeans compared to continuous corn.”
Although he uses no-till and strip-till on primarily flat ground, he said heavy rains last May were among the “worst in history” on his farm. The resulting erosion was “heartbreak.” In fall 2013, he planted winter rye as a cover crop on erosive areas and plans to expand those efforts this year.
NEW RESEARCH
Despite expansion of corn production in one of the state’s largest watersheds along the 31-mile Raccoon River, a recent Iowa Soybean Association study shows reduced nitrogen runoff into the watershed. Nitrogen transport downstream has been declining since 1999.
The Raccoon is a tributary of the Des Moines River, and the watershed as a whole includes the North, Middle and South Raccoon rivers in central Iowa. The Raccoon watershed drains some 2.3 million acres, or about 7% of the state’s land mass from 17 counties.
ISA’s Wolf said nutrients, or fertilizer, reductions were realized despite a nearly three-fold increase in water discharge from rain events. Additionally, declining sediment load points to a combination of technology changes and use of conservation technologies, he said.
“No doubt we see significant spikes with sediment loading into the ’70s and we intuitively expected that,” Wolf said. “Less expected was that in the mid-’80s we see a new equilibrium reached that is much lower than historical sediment loadings and levels have been fairly stable since then. The data paints a picture suggesting something was different within the last 25 years or so.”
Another surprise is a reduction of nitrate export via the Raccoon River from 1999 to 2013 despite “big increases” in corn acres and the use of nitrogen fertilizer throughout the basin, he said.
The reduction could be from better water management of runoff through tiling systems, Wolf said.
SEDIMENT LOADS DROP
A 93-year study, “From Agricultural Intensification to Conservation: Sediment Transport in the Raccoon River, Iowa, 1916-2009,” shows sediment loads dropped during the heart of Iowa’s ethanol expansion.
Heavy sediment loads into the Raccoon dating to 1970-1979 were more than four times higher than from 1985 to 2009. Loads dating back to 1920-1929 were more than twice the loads recorded from 1985 to 2009.
ISU’s Cruse said the majority of sediment in Iowa rivers come from stream bank erosion deposited across decades.
Chris Jones, an environmental scientist with the Iowa Soybean Association who co-authored the study, said high sediment loads in the 1970s came from new watershed land coming into production during the “fence-row-to-fence-row” crop expansion.
Conservation compliance with the 1985 farm bill, glyphosate-resistant crops that resulted in less tillage needed for weed control, and larger seed populations that produced a tighter crop canopy and protected soils from rain events, Jones said, all played a role in reduced sediment loads to the Raccoon.
“I think you would be hard-pressed to find water quality data that conclusively links increased corn acreage connected to the RFS with degradation of water quality in Iowa, either for sediment or nutrients,” he said.
Editor’s Note: Our Ag Afflueza series has been looking at the windfall farmers and the ag industry received, and what’s been done with those gains, following the commodity price boom.
