If you’ve passed by the Iowa State University research farm near Boone, you may be wondering about the plants that greened up the fields early this spring. The crop is canola.
Canola, the source of a healthful vegetable oil, may provide a marketable third crop for Iowa that helps conserve soil and prevent nutrient loss, according to research funded by the Leopold Center for Sustainable Agriculture’s Ecology Initiative.
Mary Wiedenhoeft, professor in agronomy at Iowa State University, began the project in 2009 with Ph.D. student Stefan Gailans. The experiment compares three different crop rotations:
- Conventional corn/soybean
- Corn, spring canola and winter wheat (red clover)
- Corn, spring wheat and winter canola (red clover)
The winter canola and wheat in the two alternative systems are planted in September and October and go dormant during winter months. They emerge early in spring and are interseeded with red clover, a perennial legume that keeps down weeds and adds nitrogen to the soil to enhance the corn crop that follows. The winter canola and wheat are harvested in June.
By mid-April the winter canola was waist-high and the winter wheat knee-high, with the red clover just above the ankle. The alternative cropping systems, Gailans said, “have green living cover at a time of year when there is no cover elsewhere.” Iowa’s fields are most vulnerable to soil erosion and nutrient loss in the spring and fall, when frequent rainfall strikes the bare ground. The investigators hypothesize that farmers can gain conservation benefits by growing canola, while producing an economically viable crop.
The investigators have completed the first year of the three-year rotation at the Agricultural Engineering and Agronomy Research Farm. Replicated plots of the conventional and alternative systems each started the rotation with a different crop. Gailans estimates the amount of cover on the ground by measuring the sunlight that reaches the soil.
In spring, alternative plots had 60-80% living cover, while conventional plots had zero percent. In fall, leaf litter and corn stalks covered the ground in conventional plots (50-80%), comparable to the amount of living cover in alternative plots (50-90%). While leaf litter helps prevent erosion, canola provides the additional benefit of actively taking up nutrients and water. That reduces the risk of nutrient runoff and allows farmers to harness the sunlight in a longer growing season.
Gailans will complete a full economic analysis after gathering more data, but preliminary results look promising. Corn yields between the conventional and experimental plots were comparable. The alternative plots produced roughly the same amount as the Boone County average last year, 183 bushels per acre. The conventional plots produced slightly more at 200 bushels per acre.
Winter canola produced 1,043 pounds of oil per acre, while the spring variety, which has less yield potential, produced 595 pounds. For comparison, the soybean in the conventional rotation – also an oilseed crop – produced 691 pounds of oil per acre.
“There’s a great demand for canola oil,” Wiedenhoeft said. A facility in Cherokee processes organic, non-GMO canola oil, which they currently import from North Dakota and Canada. If the experiment shows that canola can grow profitably in Iowa, the investigators envision that farmers could take advantage of this niche market.
There’s also potential for a growing market in small grains, according to Tomoko Ogawa, cover crop grains and food coordinator at Practical Farmers of Iowa (PFI). Ogawa gathered wheat berries from Gailans’ experiment, as well as samples from PFI farmers and the ISU Agronomy Farm, to send to the headquarters of franchise bakery. They will respond with feedback after conducting a bake test, and Ogawa hopes they will eventually incorporate local small grains into bakeries in Iowa and neighboring states.
“There is increasing interest in local small grains,” Ogawa said. “That’s more difficult to find than meat or produce available locally.”
One advantage of the alternative cropping systems, Gailans said, is that canola and wheat don’t require a major change in farming equipment. Additionally, the different planting and harvesting times makes the labor easier by spreading it out more evenly over the year.
“It’s good for conservation, and we’re not taking land out of production,” Wiedenhoeft said. “We’re providing farmers with a niche market that will diversify their crop portfolio. It’s a more resilient system.”
- Mary Wiedenhoeft, ISU Department of Agronomy, (515) 294-3274, firstname.lastname@example.org
- Stefan Gailans, ISU Department of Agronomy, (515) 294-2230,