Subject: Saving Iowa’s soil
If there were any scientists prone to favor Iowa’s farming techniques on April 11, none spoke up.
In a presentation titled “Hydrology of Iowa as affected by corn and soybean agriculture,” three speakers told Iowa scientists:
That Iowa has seen so much land use change that if every farm implemented every possible conservation practice, the best that could result is bringing Iowa’s natural hydrologic state is to where it was in the 1940s.
Iowa’s million miles of field tile lines, plus the increasing acres under concrete in urban areas, is causing more stream bed erosion because the volume of water is higher and moves through them faster than ever before.
Even though the winter of 2013-2014 saw a tripling of cover crops – 300,000 acres -there were still 23 million acres under row-crop production that laid bare to the elements for seven months of the year.
“If you want to change agriculture, you have to change the farm bill.”
The presentation was part of the Iowa Academy of Sciences annual meeting, held April 11 through 12, hosted by Iowa Central Community College.
Dr. Keith Schilling, a senior research scientists with the Iowa Department of Natural Resources, told his audience that with better fertilizer products and machinery, corn and soybean acres grew by 40 percent from the 1940s to 2000s.
“Prior to 1940,” Schilling said, “Iowa had more diversified crops – hays, oats, meadows.
“Today it’s mostly corn and soybeans and the trends is echoed in other Midwest states, but Iowa is the epicenter of row-crop land changes.”
With more tile lines installed, more land opened for row crops and a 130 percent increase in rainfall over the past 130 years, Schilling said, Iowa’s soils no longer act as the sponge they once did before the steel plow arrived.
Iowa soils’ water-holding ability has been broken down so far, he said, the best Iowa can improve is getting back to its 1940s capability.
“With a 4-inch rain,” Schilling said, “you can expect 3 inches to run off” without any type of conservation practices.
And if corn demand continues to grow, he said, and more acres are converted to meet the demand, there will be even more discharges into the Mississippi River Basin.
Conservation practices are holding more soil in place, said Mary Skopec, a senior researcher with IDNR, but most erosion is occurring in streambeds, and nitrate leaching occurring through tile lines.
Skopec said Iowa needs more grasses planted to hold water back.
“That’s important,” she said, “because water carries the pollutants.”
From 1995 to 2008, Skopec said, nitrate flows in Iowa’s surface waters have multiplied six times. This is from more tile lines, but also more than a million acres returned to row cropping after coming out of conservation reserve.
“Only 10 percent of Iowa’s streams would test for safe levels of nitrates today,” Skopec said.
Schilling said urban areas also carry blame for the increased water contents in streams and erosion that occurs.
With more concrete and impervious surfaces from urban developments shedding rain and snow melt into streams, the water flows faster through the watersheds, although the flows don’t last as long, Schilling said.
What can be done?
Bob Watson, an environmental activist from Decorah, outlined farm and market changes that would improve Iowa’s hydrologic capabilities, but said the real changes would happen by changing farm bill programs.
“The Iowa Nutrient Reduction Strategy is useless,” Watson said. He said it’s bound to fail because it’s a voluntary program of conservation, plus the reduction of nitrates and phosphorus goals are scales that do not reach far enough.
Watson said Iowa had re-establish its wetlands, forests and deep-rooted grass prairies.
He said by planting perennials that can be harvested for food, such as kernza, “we can eat the prairie.”
Kernza is a wheatgrass and is being developed by some seed breeders as a marketable grain for prairie states.
Such perennial grains, Watson said, would have to be replanted every several years, but between those times they’d require no tillage, fertilizer applications and, possibly, less fungicide and pesticide spraying.
The second step is mandating through the farm bill that 10 percent of every planted field have grass strips in them.
“These would stop 95 percent of the erosion,” Watson said, “soak in more rain and provide wildlife habitat.”
The third step is more acres returned to pastures for livestock grazing.
“Established pastures,” he said, “can soak in 7 inches of rain in an hour.”
The fourth step is add industrial hemp to farm rotations.
Eight states are currently cleared for growing industrial hemp.
“It’s an important food and fiber source,” Watson said, “second only to soybeans in protein.
“America is the only country that bans growing hemp, but we are the world’s biggest importer of hemp.”
The final step is returning to diversity of farming and more than two crops in a rotation to improve soil profiles.
“We’ll need 40 to 60 million small farmers,” Watson said, “to revitalize or rural economies.”