Page 234 - Environment: The Science Behind the Stories

ceNTrAl CASe STUDy

Iowa’s Farmers Practice

No-Till Agriculture

CANADA

“The nation that destroys its soil destroys itself.”
Iowa —U.S. President Franklin D. Roosevelt
UNITED
STATES
“There are two spiritual dangers in not owning a
farm. One is the danger of supposing that breakfast
comes from the grocery, and the other that heat
comes from the furnace.”

Atlantic —Conservationist and philosopher Aldo Leopold
Ocean
MEXICO

Pacific
Ocean
Iowa farmers Arliss Nielsen and Todd Nielsen know they need As a result, the Nielsens are observing the condition of
to keep their soil healthy and productive. This father-and-son their soil improve. Their tests show that organic matter is
team cultivates corn and soybeans on 500 ha (1200 acres) in increasing in their soil, and earthworms have returned after
Wright County, Iowa, where rich prairie soils have historically many years of absence. “We can see the difference in the soil,”
enabled bountiful grain harvests. Arliss Nielsen says.
Yet the Nielsens also have learned that repeated cycles The Nielsens also find that no-till farming saves time and
of plowing and planting have diminished the soil’s fertility money. By not tilling, they reduce the number of passes they
since farmers first settled the region. Indeed, much of Iowa’s need to make on the tractor, which saves fuel, time, effort, and
topsoil—the valuable surface layer richest in organic mat- wear and tear on equipment.
ter and nutrients—has been lost to erosion, washed away Along with no-till methods, the Nielsens are using cover
by water and blown away by wind. Turning the earth by tilling crops, crops planted to hold the soil in place between times
(plowing, disking, harrowing, or chiseling) aerates the soil and that main food crops are growing. After experimental attempts
works weeds and old crop residue into the soil to nourish it, but with clover and vetch, they hired an airplane to scatter rye
tilling also leaves the surface bare, allowing wind and water to grass seed. The rye grass prevents erosion when corn and
erode away precious topsoil. soybeans aren’t growing, and it makes planting easier by loos-
And so, although Arliss Nielsen had spent half-a-century ening the soil structure. Moreover, nutrients taken up by the rye CHAPTER 9 • So I l AN d A gr I culT ure
behind the plow, he and his son Todd abandoned the conven- make their way to the corn and soybeans once the rye decom-
tional practice of tilling the soil in 2005 and instead turned to poses in the topsoil. Because cover crops such as rye hold
no-till farming. Rather than plowing after each harvest, they nutrients, the Nielsens hope that over time they will be able to
began leaving crop residues atop their fields, keeping the soil reduce the amount of fertilizer they apply.
covered with plant material at all times. To plant the next crop, The Nielsens practice other conservation measures on
they cut a thin, shallow groove into the soil surface, dropped in their land as well. They take soil samples to determine how
seeds, and covered them. By planting seeds of the new crop much fertilizer different areas need, so as not to overapply it.
through the residue of the old, less soil erodes away, organic They employ planting methods designed to reduce erosion.
material accumulates, and the soil soaks up more water—all of They grow grass borders around the farm to keep soil and
which encourages better plant growth. nutrients from escaping. They plan to install a bioreactor (an 233

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