Wheat residue most valuable on the ground, scientist says

Times are good for wheat farmers, but they should resist the urge to harvest their crop residue and sell it for ethanol production, a federal researcher says.

Leaving wheat residue on the ground helps preserve the rich soil of the Palouse, while harvesting that residue would speed erosion, said Ann Kennedy, a U.S. Department of Agriculture scientist.

“In the more than 100 years that we have been cultivating soils in the Palouse, we have lost about half of the original organic matter,” she said.

That organic matter, which consists of decomposed plant material and microbes, provides nutrients, holds water and helps prevent wind erosion, Kennedy said.

Loss of that soil, built up over the millennia and augmented by volcanic eruptions, would be a major economic hit. Wheat is selling for more than $8 a bushel, double what it was a few years ago. That is injecting new money into farming areas like the Palouse.

Farmers are rushing to cash in on the high prices. The amount of land planted in wheat in Washington has risen by 250,000 acres in the past year. Winter wheat planting grew by 80,000 acres to approximately 1.8 million acres. Spring wheat grew by 170,000 acres to about 620,000 acres.

The percentage of organic matter in soil varies from region to region, depending on climate, soil disturbance, moisture and vegetation. Kennedy said the soil in the Palouse should have about 3.5 percent organic content, but in reality it is closer to 2 percent.

Kennedy said at least a ton of residue per acre per year is needed to build organic matter over time.

Leaving residue on the soil surface works best.

“It will tend to stay around longer, and the microbes will slowly invade it and convert it into organic matter,” she said.

Proposals to bale the crop residue and sell it for biofuels are bad ideas, she said.

“We need to constantly replenish organic matter,” she said.

The state’s big wheat crop is dominated by varieties developed at Washington State University, according to the National Agricultural Statistics Service.

In particular, growers have adopted a new spring wheat variety, Louise, developed for release in 2007 by Kim Kidwell, a WSU spring wheat breeder. Louise is the top variety of spring wheat planted in the state, at 155,000 acres.

Kidwell has also developed two other varieties of spring wheat in heavy use.

“The success of our breeding program is determined by how many acres of our varieties are grown by Washington wheat producers,” Kidwell said.

In winter wheat, WSU professor Stephen Jones’ Bauermeister variety topped the hard red winter wheat category with nearly 75,000 acres planted. His varieties of soft white club wheat – Bruehl and Edwin – held two of the top three spots in that category.

“Although our recent releases are terrific, we truly believe that our best varieties may be yet to come,” Kidwell said.