A long-term study in Canada appears to show that sowing wheat occasionally can increase yields enough in corn and soybean operations to make the practice economically beneficial.
Researchers in Ontario have demonstrated that growing wheat every four years or so boosts yields of the main crops by a significant percentage. The trial began in 1980 and is ongoing.
The greatest gain was with winter wheat grown every four years, said Ken Janovicek of the University of Guelph. Corn and soybeans have increasingly benefited from the rotation, with soybeans seeing the greater impact in recent years.
“Early, corn was the only crop showing benefit, but in later years both crops have,” Janovicek said.
In recent years, corn yields were increased by about 13 bushels per acre following wheat, compared to a standard corn-soybean rotation. Soybean yields in rotation with wheat averaged 10 bushels per acre higher, double the response seen earlier in the study.
The rotation pencils out even though producers make less on wheat during the fourth year. The plots are located near Toronto, which is on a similar latitude as southern Wisconsin. The soft red winter wheat grown there yields an average of about 100 bushels per acre.
“If you do the math, soybeans will generally make you more money,” Janovicek said. “We emphasize, though, that in the last four years, you can get a 10-bushel increase in soybean yields. You would never have seen that if you didn’t have wheat. That’s a benefit in your yields. You can’t just compare your soybean yields and wheat yields.”
Researchers attribute the yield benefits in corn and soybeans to improvements to the soil realized with an occasional wheat crop.
“We think it’s a response to improved soil structure,” Janovicek said. “Any time you include a small grain like a cereal crop, you get better soil infiltration, and roots grow easier.”
There may be other factors at play that aren’t measurable.
“We haven’t actually seen any difference in disease pressure,” he said. “That’s not to say it’s not hidden. We haven’t seen anything obvious.”
Growers in the U.S. Corn Belt could possibly see similar benefits. Relatively few acres are planted to wheat other than in areas farther south where it is used in a double-crop system with soybeans.
Convincing corn and soybean producers to take a pause from their main crop every few years for less-profitable wheat is a challenge. But Janovicek believes farmers who look at the overall figures will see that the strategy pencils out.
“Your soybeans might be making you $200 an acre more because of wheat. That was the whole point,” he said. “You take the system as a whole, wheat does increase profitability. You have to look at the system.”