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United States Department of Agriculture

Agricultural Research Service

STEEP Solutions to Soil Erosion

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STEEP Solutions to Soil Erosion

It describes the lay of the land in the prime wheat-growing region of Washington, Oregon, and Idaho.

STEEP—Solutions to Environmental and Economic Problems—is also the name of an innovative program that has helped give farmers the tools to reduce soil erosion up to four-fold and still grow crops profitably.

This productive region spans 10 million acres stretching from the Cascade Mountain Range to the Palouse, Columbia, and Snake River Valleys in the three states.

Almost all of the nation's soft white wheat grows here, along with barley, peas, and lentils. The total wheat crop's value for the three states was over $1 billion in 1993. Much of this wheat—used for cakes, cookies, and noodles—is exported to Asia.

But this bounty grows on some of the country's most erosion-prone soils.

"Slopes on the cropland average 8 to 30 percent, with some up to 50 percent," says Robert I. Papendick, a soil scientist in the ARS Land Management and Water Conservation Research Unit at Pullman, Washington.

Plant geneticist Bob Allen examines a stalk of the winter wheat Madsen. Click here for full photo caption.
Madsen, a soft white winter wheat developed by plant geneticist Bob Allan resists rusts and strawbreaker foot root and can be planted a month earlier.
(K5950-1)

For comparison, highways are considered very steep at a 6- or 7-percent slope.

The difficulty lies not just in the topography, but in the cropping systems and unique winter weather patterns in the Pacific Northwest.

Winter wheat is planted in the fall. The soil is covered only with small seedlings when snow falls. The soil freezes, then thaws under warm winter winds called Chinooks.

"When the snow and the top layer of frozen soil melts, it forms a gooey soup that flows down the slopes," says Dale E. Wilkins, ARS agricultural engineer at the Columbia Plateau Conservation Research Center in Pendleton, Oregon.

To reduce the runoff, Wilkins is working on a tool that breaks open the frozen ground so water can soak into the deeper soil before it runs off.

The cost of the erosion is enormous. So far, potential soil productivity in the steepest and wettest areas has been cut in half. All of the original topsoil has been lost from more than 10 percent of the 2.1 million acres of cropland in the Palouse River Basin. The eroded soil fills up roadside ditches—costing taxpayers millions to clean up—as well as rivers and lakes, which suffer environmental damage.

To combat the problem, area wheat growers banded together in the early 1970's. They encouraged scientists from the Agricultural Research Service in Pullman and Pendleton, Oregon State University in Corvallis, Washington State University in Pullman, and the University of Idaho in Moscow to jointly develop erosion-curbing technologies. The result was a federally funded 15-year program called STEEP. In 1990, STEEP II continued the nationally renowned program another 5 years.

Research associate Chris Pannkuk analyzes soil resistance in a badly eroded wheat field. Click here for full photo caption.
A penetrometer helps Washington State University research associate Chris Pannkuk analyze soil resistance in a badly eroded wheat field.
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Papendick, who has worked on STEEP since its inception, says it took on five objectives—new plant varieties, improved tillage techniques, state-of-the-art erosion prediction, better pest control strategies, and socioeconomic analyses—to ensure that the new technology would be profitable and acceptable to growers.

STEEP has reported and provided partial funding for hundreds of research projects. Here's a small sample.

Madsen—A New Wheat Variety

Strawbreaker foot rot is a devastating fungus that rots wheat stems. Wheat infected by it yields less. The grain that does ripen is hard to harvest because the rotted, grain-laden stems fall to the ground.

'The fungus thrives in mild fall temperatures, so one of the ways to control or escape the disease was to plant the seeds extremely late. But then you had a very small plant going into the winter and very little ground cover to hold the soil in place," says geneticist Robert E. Allan, who works in the ARS Wheat Genetics, Quality, Physiology, and Disease Unit at Pullman.

In 1989, Allan and colleagues released Madsen, a soft white winter wheat variety resistant to strawbreaker foot rot and to all three rust pathogens that attack wheat in the region.

Madsen can be planted up to a month earlier than other wheat varieties. It is now the most popular soft white winter wheat variety in Washington, and second favorite in Oregon and Idaho.

Conservation Tillage Keeps Soil in Place

Another way to stabilize the soil is to leave straw from the previous crop standing. Planting seeds into this residue with little or no cultivation is called conservation tillage.

Studies indicate that this technique can reduce erosion by 75 percent—from 20, down to 5 tons of soil per acre annually. But STEEP researchers learned that while the technique saved soil, the plants wouldn't grow.

Soil scientist and a farmer examine crop residues. Click here for full photo caption.
Pullman, Washington, farmer Steve Mader (left) and soil scientist Bob Papendick examine a previous crop's residues remaining after seeding with a no-till drill.
(K5957-1)

"We discovered that for conservation tillage to work—especially no-till—the fertilizer had to be placed right near the seeds, rather than broadcast on the surface," says Papendick.

The difference is because conventional tillage buries weed seeds so they can't outcompete the wheat for nitrogen fertilizer. Also, he says, tilled land naturally has more available nitrogen, because tillage aerates the soil and stimulates the breakdown of old plant material.

STEEP scientists developed prototypes of tools that could plant seeds and place fertilizer simultaneously. Commercial manufacturers continued the research and now sell the equipment.

USLE Didn't Work Here

In 1958, ARS researchers developed a set of mathematical relationships to predict soil erosion on cropland. Called the Universal Soil Loss Equation (USLE), it helps farmers choose farming practices that will minimize erosion.

"But the USLE didn't work here. It was my job to find out why and to make it work," says Donald K. McCool, ARS agricultural engineer based at Pullman.

The problem, says McCool, is that runoff in the Northwest—low-intensity rain or snowmelt flowing across thawing soils—differed greatly from conditions in the Midwest, where the USLE was developed.

Using more than 10 years of data from field measurements and experimental runoff plots in Pullman and Pendleton, McCool and colleagues modified some of the equation's mathematical variables. These modifications were incorporated into the Revised USLE, or RUSLE.

One reason farmers till their soil is to kill weeds and bury weed seeds. Like diseases, weeds thrive when tillage is reduced.

STEEP researchers collected data that supported registration of glyphosate, known first by the trade name Roundup. While it kills several important weeds, glyphosate doesn't stay active in the soil and is one of the more benign herbicides.

"Until we find alternatives to control weeds like downy brome and Russian thistle, herbicides are crucial to make conservation tillage work," says weed scientist Alex G. Ogg, Jr.

But Ogg and other STEEP scientists discovered that if crop seeds are planted too soon after the chemical is sprayed, the plants die from another pest—the root disease Rhizoctonia.

"As the herbicide weakens the weeds, Rhizoctonia pathogens increase dramatically," says Ogg. "If growers seed their crop right into that high population of Rhizoctonia, the crop is just devastated. But if they wait 3 weeks after spraying, there is much less impact."

Ogg works in the ARS Nonirrigated Agriculture Weed Science Research Unit at Pullman, and he recently took over the agency leadership for STEEP from Papendick.

Herbicides are applied to a field to kill off weeds. Click here for full photo caption.
A key component of the no-till system is application of herbicides to kill off weeds that would inhibit crop growth.
(K5958-14)

But Will the Farmers Use It?

"There's a strong impetus among farmers to solve soil erosion and other environmental problems, but they have to make a living. STEEP works to develop profitable solutions," says Douglas L. Young, agricultural economist at Washington State University.

Young serves as co-chair for STEEP II. He says that in the beginning, his analyses of conservation tillage verified farmers' fears: It wasn't profitable.

"But in later years," Young says, "after we developed additional techniques, we showed them it works and they can make money. Many growers are giving it a try."

Surveys led by John Carlson, a University of Idaho rural sociologist, showed that the number of farmers using reduced tillage on at least part of their farm increased from 54 percent in 1976 to 82 percent in 1990. No-till usage increased from 3 to 18 percent in the Palouse.

"We don't have total adoption now, but we've had a major impact," says Carlson.

STEEP II added water quality improvement to its goals and transformed the growers' role. To ensure that the research met their needs, growers advised the scientists during STEEP. Now they design and conduct their own experiments with an on-farm testing program.

Grower David W. Ostheller routinely tries new techniques on his 3,000-acre farm in Fairfield, Washington. He's conducted 10 on-farm tests in the past 3 years.

"A farmer can try something and say, 'this field looks a lot better,' but what does that mean? On-farm testing provides evidence of the benefits if something works," he says.

Ostheller's tests have shown that using a chisel to open up the ground after harvesting lentils can reduce erosion. Pea and lentil crops don't produce much residue, so other techniques are needed.

"I used to think that science was too abstract. Now I've got a lot more respect for what a scientist has to do to get unbiased information," Ostheller says.

STEEP Judged a Success

STEEP'S founders say its greatest accomplishment has been bringing together scientists of many different disciplines.

"From the simple idea of developing new wheat types, the project emerged as a multidisciplinary program to deal with a major agricultural problem. Researchers from separate disciplines now work together as a family of scientists. Farmers are going to win with these conservation practices," says Papendick.

STEEP III, if approved, will carry the program to the end of the century. Researchers will study other aspects of soil quality, as well as technologies to reduce airborne dust particles. — By Kathryn Barry Stelljes, ARS.

Last Modified: 1/4/2007
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