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Oregon State University Agricultural Research updates

Looking for leaching nitrates

Fall and winter rains in the Willamette Valley percolate through the soil, recharging groundwater and filling streams. But this same rain also can carry nutrients and pesticides from farmers' fields into the groundwater.

John Selker and his graduate students at OSU have been working with Extension agent Ross Penhallegon, farmers and fertilizer dealers to monitor groundwater for nitrates and pesticides in Lane County for the past two years.

The farmlands of the Willamette Valley.

Lane County farmers are working with researchers in OSU's Department of Bioresource Engineering to identify practices that prevent nitrogen from leaching into groundwater on farmland. Photo: OSU Extension and Experiment Station Communications

Impetus for the ongoing study came from farmers in the county wanting to know if their activities affected the aquifers that supply much of the county's groundwater.

According to Selker, associate professor of bioresource engineering at OSU, more than 20 percent of the drinking water wells in agricultural areas of the Willamette Valley exceed the Federal drinking water standards for nitrate.

"We're testing for pesticide and nitrogen fertilizer leaching from orchards and fields of berries, mint, grass seed and several row crops," said Selker.

"The good news is that there were no pesticides found above drinking water standards in any of the samples," he said. "The not-so-good news is that nitrogen leaching into the groundwater was a problem on some farms."

Selker and his colleagues are working with the farmers to find the right blend of "best management" practices. These include revising irrigation schedules, planting cover crops to bind nitrogen and carefully managing fertilizer applications.

"We have shown on Lane County farms that as we help farmers avoid losing nitrogen to the aquifers, we both improve environmental quality and save farmers a considerable amount of cold, hard cash."

Manure fertilizes corn, not groundwater

Back when everyone had just a few dairy cows, manure wasn't a problem. But in recent decades, there has been a shift from acres per cow to cows per acre.

Illustration of a cow wearing sunglasses.

Illustration: Tom Weeks

"Maximum efficiency and production have tended to put more cows on fewer acres," said OSU extension soil scientist John Hart. "A higher concentration of cows means concentration of manure and the nutrients in manure. Between 60 and 75 percent of the nutrients in feed eaten by a dairy cow is excreted as waste. If manure from one cow can fertilize up to 1.5 acres and a producer has five cows per acre, the nutrients from manure are going to start piling up pretty fast."

Spreading too much manure year after year can build residual nitrogen that can leach into the groundwater, risking human health, explained Hart. In addition, excess nutrients such as potassium may affect the health of the dairy herd as well.

Hart and his colleagues have been working with about 20 Oregon dairy farmers to help them use surplus dairy manure to fertilize their silage corn.

They verified that all the silage corn fertilizer needs could be met by spreading manure that was piling up in their barns and storage lagoons.

"Few of the sites studied needed added fertilizer," noted Hart. "Our immediate advice to dairy producers was, 'If you are buying fertilizer, stop. If you are spreading manure, do so more carefully.'"

Using manure to fertilize crops, instead of purchasing commercial fertilizer, now saves some of the farmers as much as $10,000 per year.

Oregon has about 90,000 dairy cows on 500 farms. They produce about $240 million a year in raw milk. Major dairy areas include Tillamook, Klamath, Coos and Malheur Counties and most of the Willamette Valley.

Ducks ducked scrutiny

Wildlife biologists at Oregon State University are finally shedding some light on the biology of the elusive harlequin duck. These colorful diving ducks spend most of the year on rocky ocean coasts, feeding on mussels, chitons, limpets and other marine invertebrates. Each spring, they disappear inland to rushing mountain streams to mate and rear young.

Four ducks on a rock in the river.

Male harlequin ducks congregate on Oregon Cascade mountain streams each spring. Photo: Robert Jarvis

OSU wildlife professor Bob Jarvis and graduate student Howard Bruner have spent three field seasons walking up many miles of rushing Oregon Cascade mountain streams, searching for breeding and nesting harlequins.

Until the OSU study, very few harlequin duck nests had ever been found in Oregon.

"Just a couple have been found incidentally, most around campgrounds," said Jarvis.

From their studies Jarvis and Bruner have learned the following about harlequin ducks:

  • They are extremely faithful to their nesting sites, returning to the same site year after year.
  • Male harlequins come inland only to breed. They return to the coast as soon as females begin incubation.
  • Predation is the most common cause of nest failure. Biologists have yet to determine the culprits. Otters, minks, bobcats, raccoons, skunks, ravens and coyotes are all suspect.
  • About one-third of the females nest at stream level while two-thirds nest upslope of the stream, up to several hundred meters away from the water. They seem to prefer steep slopes with thick plant cover, a clear flyway to the water and streams with boulders and logs. They nest on the ground, on stumps or in cracks on rocky slopes, and line their nest with a thick layer of down.

Jarvis plans on continuing to band and study harlequins to learn more about how long they live and whether the young return to their home stream or disperse to other streams.

Septoria guide available

Oregon State University agricultural researchers are now publishing a yearly report for growers on the biology and control of the septoria diseases of winter wheat in western Oregon.

The publication, the result of cooperative research between the Departments of Botany and Plant Pathology and Crop and Soil Science, covers the biology of the fungi that cause the disease and presents guidelines for control of the disease.

A wheat plant.

Photo: OSU Extension and Experiment Station Communications

Septoria has become more of a problem on wheat crops in the Willamette Valley during the last several years, explained Russ Karow, cereal crops specialist with the OSU Extension Service. Both of the fungi that cause the septoria diseases can cause significant yield loss on susceptible cultivars. One of the septoria fungi infects and discolors the seed head, making it difficult for growers to meet standards for wheat quality. Exceptionally low bushel weights and discolored grain may result. Growers then may be forced to sell the wheat at a lower price for livestock feed instead of human consumption.

The environmental conditions in the Willamette Valley are very favorable for the septoria diseases, explained Karow. A rainy year means the fungus most likely will thrive.

"The Biology and Control of the Septoria Diseases of Winter Wheat in Western Oregon" (Special Report 960), published last spring by the OSU Agricultural Experiment Station, is available for reading at county offices of the OSU Extension Service in western Oregon. An update will be available soon. For additional information, contact Russ Karow, Extension Cereal Specialist, Department of Crop and Soil Science, OSU, Crop Science Building, Room 107, Corvallis, OR 97331-3002.

Gloomy winters take toll on Oregon llamas

Just like many of us humans, some llamas and alpacas react poorly to the eternal gloom of a rainy, overcast Oregon winter.

A llama.

Llamas with a vitamin D deficiency can develop tender joints and knock knees. Photo: Brad Smith

According to recent research findings at OSU, the northern latitudes and often overcast conditions during winter months can cause a vitamin D deficiency in llamas that leads to rickets, a crippling bone disease.

This problem had been increasing over the past several years as the size of the Oregon llama and alpaca populations grew, and concerned ranchers eventually turned to OSU for help. Oregon has the largest llama and alpaca herds in the nation, with a market value that exceeds $50 million. The university has the largest llama research program in North America.

"Llamas and alpacas are native to the Andes Mountains of South America," said Brad Smith, an associate professor in the OSU College of Veterinary Medicine. "The sun is very intense near the equator, and they often live at high altitudes and are exposed to intense ultraviolet light throughout their lives."

The result, Smith said, is that in their native habitat llamas get lots of sun, even in winter, which helps llamas and other mammals-including humans-naturally synthesize vitamin D in their skin. Otherwise, this vitamin, essential for normal bone growth, can be in short supply.

Several factors are known to cause rickets, which can cause stunted growth and permanent, crippling injury to animals if not treated and prevented.

"The first tipoff that vitamin D was the problem was that the incidence of rickets seemed to be much worse in the winter months and among the crias (babies), which are a stage of development where their bones are growing most rapidly," Smith said. Smith worked closely with Bob Van Saun, and assistant professor in the OSU College of Veterinary Medicine, and Dr. Pat Long, a local veterinarian.

"Some of these crias were barely half the size they should have been. They had tender joints, knock knees and other problems," he said.

Blood analysis and other tests confirmed that vitamin D was the root of the problem, Smith said, and supplement regimens were developed to cure it. The treatments are making a big difference in the health of affected llamas, he said, and vitamin supplementation in food-similar to the vitamin D-fortified milk that humans consume-may provide a permanent solution.

"The work we've done has shown that the ability of llamas to synthesize vitamin D is limited during the winter," Smith said. "Some animals had blood levels of the vitamin 20 times higher in late summer than during the winter. And at its worst, the vitamin D blood level in affected crias was less than 10 percent of what it should have been to be healthy."

Mites chomp pests in Oregon mint fields

OSU researchers have enlisted the support of armies of tiny predator mites to help mint growers control destructive spider mites in mint fields. As a result, many growers in the Pacific Northwest may eventually cut pest control costs in half and considerably reduce their need for pesticides.

Spider mite control is a constant concern to Oregon's $51 million peppermint industry. Spider mites feed on plant juices and are capable of multiplying rapidly when weather conditions are hot and dry. Predator mites are an ideal means of control because they feed exclusively on spider mites.

Three college students in a mint field.

Mark Morris, OSU doctoral student, checks mint leaves for spider mites in a field near Jefferson, Oregon. Photo: Bob Rost

Before the introduction of predator mites, mint growers relied on the pesticide Comite for spider mite control, often spending up to $35 an acre in product and application costs. With help from predator mites, pesticide applications can be reduced, significantly lowering pest control costs, according to Mark Morris, an OSU doctoral student who works in research and development for A.M. Todd Co., a mint handler near Jefferson, Oregon.

Predator mites (Neoseiulus fallacis) occur naturally, said Brian Croft, professor in the OSU Department of Entomology working with OSU's Agricultural Experiment Station. So growers have to minimize the pesticides that might kill the good mites.

So far, experimental application of predator mites to control spider mites has worked well in mint, said Croft. A big plus is the fact that predator mites multiply quickly in sprinkler irrigated mint.

Croft is also interested in the application of predator mites in strawberry crops and ornamental plants and trees. He currently has projects underway to explore the effectiveness of predator mites in those areas.

Soil test helps hop growers steer clear of contaminated soils

A new soil test developed at OSU may save thousands of dollars for Oregon hop growers by helping them avoid planting new acreage on contaminated soils, according to an OSU agricultural chemist.

The test is designed to detect the presence of heptachlor pesticide residues in the soil. The residues are toxic to some varieties of hop plants, said Jennifer Field, an assistant professor in the OSU Department of Agricultural Chemistry and a researcher with OSU's Agricultural Experiment Station.

A woman and a a man look at a tall hops plant in a field.

Jennifer Field (left) and hop grower Bruce Davidson inspect hops affected by pesticide residues in the soil. Photo: Bob Rost

Production from new hop plantings on soils containing heptachlor residues is so low as to be barely worth harvesting. The test is intended to help growers avoid the expense of planting new acreage that is likely to fail because of soil contamination. The standard soil test used by growers does not consistently detect the presence of heptachlor.

Heptachlor pesticides were used in the mid- to late 1950s and banned in 1972, but residues of this chemical have remained stable in the soil over several years, Field said.

Today, hop growers in the mid-Willamette Valley are expanding acreage into areas where potatoes and strawberries were once grown, and the heptachlor residues in some of these fields have become a costly problem.

"When you consider that planting costs, including the hop trellis consisting of hundreds of wooden poles and thousands of feet of heavy wire, can reach up to $5,000 per acre, growers are left to absorb staggering losses when new crop acreage fails," Field said.

Researchers develop method to protect groundwater

Oregon growers may soon be better able to predict-and help prevent-pesticide contamination of the groundwater below their farms.

OSU Extension Service soil scientists and agricultural chemists are developing a new decision-making method to assess the potential for groundwater contamination by 300 pesticides, on any soil type in Oregon.

Close-up photo of soil layers.

OSU researchers are working on a method, based partially on soil type, that farmers can use to predict the risk of groundwater contamination. Photo: Lynn Ketchum

Called the "Oregon water quality decision aid," the method will help growers find out how vulnerable their specific soil types are to transmitting pesticides into the groundwater. They can use the method before pesticides are chosen or applied, said Herb Huddleston, soil scientist with the OSU Extension Service.

"We want to be able to predict the risk of groundwater contamination all over Oregon in terms of soil type and pesticide type," said Huddleston.

To develop the water quality decision aid, Huddleston worked closely with OSU Extension chemist Jeff Jenkins. Huddleston and his associates first classified each Oregon soil type according to its potential to transmit a chemical below the root zone, resulting in a "soil sensitivity rating."

Meanwhile, Jenkins and his colleagues in the OSU Department of Agricultural Chemistry organized a computer database for more than 300 pesticides that may have been used or currently are being used in Oregon.

The database includes several pesticide properties and provides a "movement rating" for each pesticide, ranging from extremely low to very high.

Huddleston and Jenkins combined their work to produce a few prototype groundwater vulnerability maps. As more soil geographic data becomes available, more maps will be prepared.

"Ultimately we hope to develop this decision tool to the point that, with a few quick computer entries, the grower could see how soil sensitivity and pesticide properties interact," said Huddleston. This would help evaluate the risk associated with the use of any particular chemical on any of the soils under consideration, he said.

Huddleston added that the "Oregon water quality decision aid" method should be ready for public use later this year.