By Amy Petherick
Caption: Underseeding red clover in spring wheat may be a beneficial strategy, as OMAFRA’s Scott Banks has found. Photo courtesy of Scott Banks.
Too many variables often make it difficult to recreate the same effective strategy year after year in agriculture.
But researchers and farmers are persevering in their efforts to find reliable tactics that work, and have managed to do so again with a study that indicates underseeding red clover in spring wheat can add up to an extra $100 per acre advantage for the following year’s corn crop.
The findings were produced by Scott Banks, the emerging crop specialist based with the Ontario Ministry of Agriculture and Food and Ministry of Rural Affairs office in Kemptville, Ont. The project was started at the Winchester Research Farm back in 2009 – at first as a regionally significant trial – but now offers implications for farmers across the province, he says.
Although spring wheat accounts for a much smaller portion of wheat production in Ontario (just 80,000 acres were harvested in 2013 compared to more than one million acres of winter wheat), the eastern part of the province traditionally grows more spring wheat than winter wheat. Of all the acres grown in Ontario last year, 37,000 acres of spring wheat was produced in eastern counties, while winter wheat production only accounted for 25,000 acres. Growers say winters, especially in far eastern Ontario, are too hard for winter wheat production to be consistently reliable. Most of the growers that are still growing spring wheat are yielding 60 to 80 bu/ac. There is a strong straw market in this area, in addition to the rotational advantages. Red clover has the added advantage of improving soil health and fixing nitrogen for the next year’s corn crop. But Banks says spring wheat growers have become reluctant about the practice.
“One of the bigger complaints growers had about red clover is that it will compete with the spring wheat crop, suppressing grain yield,” Banks says. “That becomes an issue for combining and can become a bit of a challenge for straw too, particularly for guys who are selling it.”
In an attempt to determine the best red clover seeding date to minimize competition with spring wheat, Banks says they began by broadcasting seed at four spring wheat growth stages, which included during planting, at herbicide application (typically Zadok stage 26-30), at flag leaf emergence or after harvest. Single-cut and double-cut red clover were assessed, both being broadcast at a rate of seven pounds per acre. The wheat crop received 90 lbs/ac of actual nitrogen in all cases and herbicide was applied on an as-needed basis per year.
“As you would expect, the red clover that was seeded early in the spring, at planting or even at herbicide timing, established better,” says Banks. “There was more volume of red clover going into the fall, which contributed more nitrogen and organic matter to the field, and so there was more advantage to earlier planting.”
At harvest, Banks says they were surprised to see that the red clover treatment had not suppressed spring wheat yields but had actually slightly increased yield.
“When we looked at it over the four years, for most years there was a two- to three-bushel increase in spring wheat by having red clover there,” says Banks. “Statistically, that may not be valid, but we didn’t see a reduction in the spring wheat yield.” More importantly, he says, was the impact on the corn crop the following year. “As we’ve seen in winter wheat, the red clover’s impact on the corn showed up as a fair contribution to yield.”
With nothing more than 100 lbs/ac of actual nitrogen applied to the following year’s corn crop, Banks says they saw anywhere from a five to 22 bu/ac yield boost from the red clover. The red clover treatment that performed the best was the single-cut clover that was seeded at planting for a gain of $99.57/ac, based on a corn value of $4.50/bu.
“Overall, single cut maybe looks like it contributed a little bit more to the yield but it was hard to say; statistically, there’s a difference,” Banks notes. “Single cut sometimes looks more lush, but it’s hard to say it was any more than a visual thing and I don’t think there’s a big enough difference to go one way or another.”