Pairing Winter Camelina & Double-Crop Sunflower
Wednesday, March 25, 2020
filed under: Rotation
The west central Minnesota community of Morris is, in a given year, surrounded by mile after mile of corn and soybean fields. Sunflower? Virtually none. And double-cropped sunflower? None — as in zero.
For the past two years, however, double-cropped ’flowers did bloom on a few acres near Morris. They were a central component in research being conducted at the USDA/ARS North Central Soil Conservation Research Laboratory at Morris. The other key study component was winter camelina.
Camelina is an annual in the mustard family (Brassicaceae) and related to canola. There are both winter and spring forms of camelina, with the winter types being extremely freeze hardy. Winter camelina has been shown to have cover-cropping benefits similar to rye (e.g., cold hardiness, fast spring growth, and the ability to improve water quality by helping reduce nitrate leaching). It also provides a good early spring source of nectar and pollen for honeybees. And finally, winter camelina has, like other cover crops, proven to aid with weed control by suppressing weed growth.
While U.S. acreage of winter camelina is still very minor, its oil is gaining attention for both industrial and food uses (it has GRAS status). Among those uses are as a “green” jet fuel, in bioplastics, as a cooking oil — and as a high-value animal feed supplement.
Russ Gesch is a research plant physiologist with the ARS station at Morris. He has studied camelina for a number of years and was the lead scientist* in a two-year project (2018 and 2019) looking at developing systems to enhance both camelina and sunflower production, while simultaneously realizing the ecosystem benefits of a cover crop. Specifically, the study sought to (1) determine yield tradeoffs between conventional (full-season) and double-cropped sunflower, and (2) determine the impact of double cropping of camelina and sunflower on soil moisture.
“We showed a number of years ago that we could potentially double crop a short-summer annual crop, such as an early maturity soybean and sunflower, after winter camelina,” Gesch relates. Those earlier investigations resulted in a double-cropped soybean yield that was about 80% of the conventional, and a double-cropped sunflower yield of about 72% of the conventional/full-season yield.
In the 2018 and 2019 trials, the ARS team employed four oil-type sunflower hybrids. Three were current commercial varieties (549CL from Croplan, Nuseed’s Falcon and MY 8H456CL from Mycogen). The fourth was Honeycomb, an early maturity semi-dwarf variety (provided by ARS sunflower geneticist Brent Hulke).
“We planted Joelle winter camelina in the fall of 2017, the first season of the study,” Gesch explains. “In 2018 we tilled, fertilized and incorporated Prowl preplant before seeding the ‘control’ sunflower on June 7. We harvested the camelina and planted the double-crop sunflower on July 11.” The control ’flowers were harvested on four different dates, beginning with Honeycomb on September 12 and ending with the Mycogen variety on October 4. The 2018 double-crop ’flowers were harvested the week of October 16-23. Soil moisture was measured to a one-meter depth between June 7 and the final sunflower harvest date.
Yields on the control sunflower hybrids were excellent in 2018, running between 3,000 to 4,000 kg/ha (2,670 to 3,570 lbs/ac). However, a hard killing frost on October 4 sharply reduced the double-crop yields, with Honeycomb being the only hybrid to attain physiological maturity. Its double-crop yield was about half that of the control yield, while the other three hybrids were much lower.
The 2019 results were quite different. Overall yields on the control sunflower were much lower than in 2018 — mainly due, Gesch says, to excessive late-season moisture, disease and some insect pressure. However, compared to 2018, the double-cropped ’flowers yielded better relative to their full-season counterparts. The 2019 double-cropped Honeycomb seed yield, for example, was just 19% less than that of the full-season.
Not surprisingly, 2018 oil contents were lower on the double-cropped sunflower — though only by 3% on the Honeycomb. (Oil content data are not yet available for the 2019 sunflower trials.)
Gesch and his group also looked at total seed yield — sunflower plus camelina — for the double-crop system. In 2018, the camelina yielded poorly and constituted a minor portion of the combined yield, which in turn was much lower than the full-season sunflower seed yield. The story was different in 2019, however, where the combined yields of camelina and double-cropped ’flowers was significantly higher than those of the full-season sunflower hybrids. “Remember, too, that in a double-crop scenario, we’re getting benefits from camelina as a cover crop as well,” Gesch points out. He adds that with Honeycomb’s early maturity, “we can harvest that — and still have plenty of time, even as far north as we are, to establish a fall-planted camelina.”
Soil moisture was not a problem in either 2018 or 2019 in the double-crop plots. “In 2018, soil moisture was a little lower in the double-crop treatments, but not low enough to cause any sort of drought stress,” Gesch says. Rainfall was above average in both years — and particularly so in 2019, he adds.
The Morris ARS group does not plan to conduct more camelina/sunflower double-crop work in 2020. “However, the next experiment I plan to conduct — which will probably roll out in 2021 — is to evaluate the potential for relay-cropping sunflower with winter camelina,” Gesch says. “I will also add some double-cropping treatments that include earlier sunflower hybrids than those used in the previous study.” — Don Lilleboe