Researchers seek alternatives for traditional crop rotations

2013-02-28T05:00:00Z 2013-03-01T10:12:08Z Researchers seek alternatives for traditional crop rotationsBy Gene Lucht Iowa Farmer Today Iowa Farmer Today
February 28, 2013 5:00 am  • 

AMES — Imagine an Iowa that is not completely brown and drab in November and March. 

That is the Iowa Mary Wiedenhoeft and her fellow researchers at Iowa State University are checking out through their experiments with cover crops and alternative rotations.

Wiedenhoeft, a professor of agronomy at ISU, is working with graduate students Stefan Gailans and Rafael Martinez-Feria on researching the possible use of canola, wheat and red clover as part of a crop rotation in Iowa.

The challenge isn’t whether the crops can be grown in the state, although neither is a common sight on Iowa farms.

The challenge is to see if they can be grown in a crop rotation with corn and soybeans that will allow Iowa farmers to save the soil and make a profitable living.

“We’re trying to provide alternatives for Iowa farmers,” says Wiedenhoeft, who is conducting the research with the help of grants from ISU’s Leopold Center for Sustainable Agriculture and the USDA’s Sustainable Agriculture Research and Education (SARE) program.

Those alternatives could become even more important if weeds and pests develop resistance to existing chemical controls.

There’s evidence to support the idea moving to a rotation containing alternative crops could help reduce pest and weed pressure and thus allow farmers to reduce chemical or nutrient use, Gailans says.

“Sometimes if we introduce different species (of crops) weeds get lost,” he adds.

Look at it this way, he explains. Most farmers in Iowa use a corn-soybean rotation. A few plant continuous corn.

Only a few plant alternative crops or use a longer rotation. Weeds and pests adjust over time.

Adding a twist to the rotation changes the pattern and throws off weeds.

Combine the fact using a winter cover crop can reduce erosion, and the team sees good reason to investigate the options.

One of the things they are

trying to determine is how late farmers could plant cover crops and still be able to have them germinate and grow in the fall before winter hits.

For example, researchers know canola can be grown successfully in Iowa, and there are some limited markets for processing its oil in the state.

But, Martinez-Feria is working to see how late the canol can be planted in the fall.

He knows canola planted at Labor Day can be grown successfully.

But, if a farmer waits until after soybeans are harvested and plant on Oct. 1 or Oct. 15, it is

questionable if the canola can still be planted and a stand established in the fall.

Gailans is working with several rotations of crops.

One would start with corn the first year. The second year, canola would be planted in the spring. When it is harvested in the fall, wheat would be planted.

In the spring, red clover would be planted into the wheat. Another rotation would switch the canola and wheat parts of that three-year rotation.

Canola can yield about 1,500 to 2,000 pounds per acre and the wheat about 55 to 60 bushels per acre, he says.

The canola is sold to be processed into oil. Wheat is being sold and processed into flour.

Some nitrogen is added (that would not otherwise be used if soybeans were in the rotation), but no chemical pest suppression is used on the canola.

In some cases, the summer versions of these alternative crops are grown successfully in Canada and North Dakota, while the winter versions are grown successfully south of Iowa.

The goal is to learn whether farmers can push those crops farther north or south and make them parts of successful rotations here.

“We want some winter cover,” Wiedenhoeft explains.

By reducing erosion, she says farmers also may be able to improve their farms and avoid environmental regulation.

“We would like to eliminate the brown zone in Iowa,” Gailans adds.

“We’re not inventing this stuff. The idea is to give farmers options.”

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