Blessed with Soil and Precious Little Water

It all starts with the soil.

On the Columbia Plateau, soil is a treasure that was deposited thousands of years ago when glaciers scoured volcanic rock into fine silt. As the glaciers retreated, wind whipped the silt into drifts of deep, rich soil called loess. Those highly productive loess soils help make the Columbia Plateau one of the premier wheat-producing regions in the world, according to Steve Petrie, superintendent of Oregon State University’s Columbia Basin Agricultural Research Center (CBARC) near Pendleton.

Gazing out his office window at the rolling wheat fields and the foothills of the Blue Mountains to the east, Petrie talked about the challenges growers face in this region that is rich in soil but averages 20 inches or less of annual rainfall.

“Many parts of the Midwest average 35 bushels of wheat per acre with 40 inches of annual rainfall,” he said. “Yet growers here often get 45, and sometimes over 50, bushels per acre with as little as 12 to 14 inches of precipitation.” Petrie added that producers in the Midwest grow a crop every year, while many eastern Oregon farmers use a crop-fallow rotation system in which they grow a crop every other year. The reason for the crop rotation is water. In this dryland agricultural system growers are totally dependent on rainfall to supply water for crops.

“Water is our most limiting factor for agricultural production,” Petrie said. At the Columbia Basin Agricultural Research Center, part of Oregon’s Agricultural Experiment Station, scientists study all aspects of dryland agriculture in this land blessed by soil and short on water.

OSU soil scientist Dick Smiley takes a close look at Fusarium crown rot in young wheat plants. Photo: Lynn Ketchum		OSU agronomist Stephen Machado tests the planting depth necessary for wheat to thrive in this region of dryland agriculture. Photo: Lynn Ketchum

The Columbia Plateau extends 60,000 square miles in eastern Oregon and Washington and parts of western Idaho. In Oregon, it includes nearly one million acres of cropland planted to dryland cereal grains, mostly soft white winter wheat that is exported to Asia, and smaller amounts of spring wheat and barley. Dryland wheat farming in the region began more than 125 yearsago. Today, wheat is one of Oregon’s top agricultural commodities, earning growers more than $180 million in farm gate sales in 2004.

CBARC includes research facilities located on 160 acres a few miles northeast of Pendleton, and additional facilities located on 234 acres of land in Sherman County near the small farming community of Moro. Conducting research at both sites is vital to successfully serving area growers, said Petrie, because soils, rainfall and climate conditions vary significantly throughout the region.

“The area around Pendleton receives about 17 inches of rainfall annually, while the wheat-producing parts of Wasco, Sherman, Gilliam and Morrow
counties get 10 to12 inches of rainfall each year,” Petrie said. “It may seem like a minor difference, but it has far-reaching effects on crop management. Our scientists conduct field trials in both climate zones so we can tailor research to the specific requirements of growers in the two areas.”

Petrie leads a team of OSU Agricultural Experiment Station faculty and staff at the center who work closely with research colleagues from Washington State University and the University of Idaho; and with USDA Agricultural Research Service scientists who share the research facilities. This collaborative group combines forces on many kinds of research, including helping growers control soil erosion and improve soil water management. Loess soils, created by ice and wind, are very susceptible to erosion by water and wind.

CBARC scientist Don Wysocki points out characteristics of Columbia Basin soil during a field day demonstration. Photo: Margaret Herring		Yellow fields of canola create a patchwork landscape where growers rotate crops to help reduce soil erosion. Photo: Lynn Ketchum

“Wind and water erosion continue to be our biggest resource problems,” said Don Wysocki, an OSU Extension soil scientist at CBARC. Wysocki is part of a collaborative program called STEEP (Solutions to Economic and Environmental Problems), launched in 1977 to improve farm profitability and environmental quality by developing practices that conserve soil moisture and help control soil erosion.

STEEP addresses these problems in three main ways, according to Wysocki.First, by managing crop residue, which is the plant material left in the field after harvest. Second, by considering crop rotation, which is the practice of planting different crops in successive years. For example, a grower might plant wheat one year, followed by barley the next year. Crop rotation adds organic matter that enriches soil and helps break the cycle of plant disease and weeds that build up over time. And third, by considering tillage practices, which are practices such as plowing, discing or harrowing, that growers use to prepare the soil for planting.

The traditional cropping method Oregon wheat producers have used for many years is the winter wheat/summer fallow production system where the grower plants wheat in the fall, the plants emerge and overwinter in the field and begin active growth in the spring. This allows the crop to take advantage of winter rainfall. After harvest in July the fields are left untouched, or fallow, to collect rainfall through the winter months. In spring growers till fallow fields and apply herbicides to control weeds. The fields remain in this condition until fall when the next crop is planted.

However, the practice of leaving crop
fields fallow can lead to extensive soil erosion over time, which reduces soil productivity and adds to sediment in waterways.

“Direct seeding, which largely excludes tillage, is gaining in importance as a crop management practice,” Wysocki noted. Direct seeding simply means the crop is planted directly into the soil through the crop residue layer using specially designed drills. “It is just one part of the larger cropping system that includes different crops, in addition to wheat, that may be included in the grower’s crop rotation.”

With funding support from USDA, Wysocki cooperates with WSU and UI agricultural scientists to provide information and workshops throughout the Columbia Plateau region to introduce growers to alternative cropping strategies.

Has progress been made?

“Absolutely,” Wysocki said. “This landscape looked a lot different 20 years ago. Today, there’s significantly less cropland left fallow. More growers are leaving crop residue on the surface in their fields and direct-seeding.

“However, adopting new cropping systems is a gradual process,” said Wysocki.

To help that process along, scientists at CBARC rely on several long-term field experiments designed to evaluate the effects of various cropping practices on soil and crop productivity. Established in 1929, these plots are the oldest agricultural research tracts in the western United States and are one of the center’s most effective research and education tools, according to Petrie. The long-term plots help scientists evaluate fertilization treatments, tillage practices and crop rotation used in the region. For comparison, the plots also include a grassland section that has received only minimal management since 1931.

The project is currently coordinated by OSU agronomist Stephen Machado, who established additional experimental plots at the Moro Station in Sherman County in 2002.

“It is my opinion, based in part on what we’ve learned from the long-term experiments, that the winter wheat/summer fallow rotation cropping system is slowly killing the soil life, depleting organic matter that gives the soil water-holding and nutrient-holding capacity,” Machado said.

Machado tells growers that when they are standing in a crop field, “they are standing on the roof of another world.

“There are living organisms beneath the soil surface — fungi, bacteria, nematodes and other organisms that make up the living system that supports crops we produce,” Machado said. “We must do whatever we can to keep this system thriving. Moving towards annual cropping systems where land is planted and produces a crop every year is an important step in the right direction. Plant material from annually grown crops protects surface soil from erosion and adds more organic material that enriches soil and improves its water holding capacity.”

Through ongoing planting trials at Moro and Pendleton, researchers help identify crops adapted to the region that have potential for improving soil productivity and farm profitability. Machado and others at CBARC have evaluated a broad range of candidates, including legume crops such as chickpeas and lentils and oilseed crops such as safflower and sunflower.

“There is an important economic component to alternative crops research,” said Machado. “It’s not enough to identify crops that are adapted to the climate here and will yield well. Market potential is key to the grower’s decision on whether to try a different crop.”

Of the crops Machado has surveyed, mustard (used for making the condiment) has been attractive to growers. Wysocki is evaluating canola, a seed crop that may become important to biodiesel production. Petrie is investigating barley with OSU barley breeder, Pat Hayes, identifying fertilization and crop management practices that will produce the best possible barley quality for animal feed and for making beer.

Dan Ball works with plants too, but his goals are far different. As a weed scientist at CBARC, Ball studies ways to stop undesirable plants from growing in and around eastern Oregon crop fields.

“A major concern in this region is that weeds compete with crops for the limited soil water available,” Ball said. “Competition from weeds such as jointed goat grass and downy brome can cut grain yields by more than 20 percent.” And if left unmanaged, weed populations escalate and weed problems grow worse from year to year.

“Tilling crop fields has been the dominant weed control technique in this area for many years, but more growers are beginning to employ cropping systems that reduce or eliminate tillage,” Ball said. “This helps reduce soil erosion, but it increases weed problems because in the absence of plowing, weed seeds are left near the soil surface where they can sprout and grow easily.”

For example, Ball explained, the weed rattail fescue is common to eastern Oregon’s dryland wheat growing region, but it wasn’t a significant problem until growers began transitioning to direct seed cropping systems. The absence of plowing turned out to help rattail fescue establish and spread, creating a new problem for growers.

Growers employing direct seed cropping systems use crop rotation to break the annual cycle of weed growth, and they use herbicides to control weeds chemically.

“However, herbicides are just one of many tools available for weed control, and they are best used judiciously,” Ball noted. “Some of these products can persist in the soil and affect other crops grown in rotation. Excessive use can lead to weeds with resistance to chemicals, which of course makes those weeds more difficult to control.” Ball is currently developing laboratory tests to detect herbicide resistance in weeds, in addition to field trials he conducts to ensure that herbicides used in the region are effective in controlling weeds.

Breeding new varieties of wheat that are resistant to root lesion nematodes demands the attention of CBARC research assistant Sandra Easley. Photo: Bob Rost		CBARC superintendent Steve Petrie stands atop a legacy of soil that OSU scientists and growers are working together to sustain. Photo: Lynn Ketchum

In addition to weeds, growers must manage plant diseases. There are many cereal crop diseases, some with vivid names such as take-all root rot, flag smut, strawbreaker foot rot, snow molds and stripe rust. In his two decades at CBARC as a plant pathologist, Dick Smiley has worked on most of these diseases. He has found that the occurrence of crop diseases tends to ebb and flow depending on environmental conditions and crop management practices.

“Because rainfall and water management in soil is a driving factor in all of the agricultural systems here, plant diseases here are very strongly affected by soil moisture,” Smiley said.

For example, Fusarium crown rot is less serious in moist years than in dry years. The fungus attacks wheat plants, causing the upper portion of the plant’s root system (the crown) to rot. When drought conditions stress plants, the fungus is much more successful in destroying plant tissue. It can shut down the plant’s ability to transmit moisture up from the roots into the upper portion of the plant, Smiley explained.

The Columbia Plateau is one of the premier wheat-producing regions in the world. Photo: Bob Rost

“We’ve spent many years studying root diseases and I think we’ve done about all we can in terms of adjusting planting date and fertilizer application to improve production efficiency and maximize disease control,” Smiley said. The next step is to build genetic resistance to root diseases.

“This has been a growing emphasis over the past four years,” he said. “We’ve received disease-resistant plant material from Turkey, Australia and the International Center for Wheat and Maize Improvement in Mexico that we’re using in cross-breeding experiments to introduce disease resistance into local wheat varieties.”

During a trip to Australia in 1999 Smiley encountered a new kind of threat to eastern Oregon wheat crops: root lesion nematodes. Nematodes are microscopic worms that are present in all soils everywhere. Many kinds are beneficial. However, root lesion nematodes damage the roots of wheat plants, reducing their ability to take up water and nutrients.

“We didn’t think this was an issue in our area and in wheat-fallow rotations it probably isn’t that great an issue,” said Smiley. “But in annual cropping systems the nematode populations tend to increase and there is greater potential for crop damage.”

Smiley and research assistant Jason Sheedy, a nematologist from Australia who joined the CBARC staff earlier this year, are conducting cross-breeding experiments to genetically introduce resistance to root lesion nematodes into local wheat varieties.

Annual cropping, direct seeding, chickpeas, canola, rattail fescue, root lesion nematodes—what’s next?

“In one way or another, all of the scientists and staff at CBARC work towards helping growers produce better crops,” Ball said. “But I like to think that as researchers working with local farmers, we’re doing more than just improving crops. The bigger goal is helping rural economies and communities. Ultimately, that’s why we’re here. That’s really what we do.”

To learn more about Columbia Basin Agricultural Research Center:
http://cbarc.aes.oregonstate.edu/