How much stover can be taken sustainably?OAKES, N.D. — The North Dakota Corn Growers Council and various corn seed companies are financing a study in Oakes, N.D., to determine how much corn stover can be removed for use in ethanol or biomass production and still maintain soil productivity.
By: Mikkel Pates, Agweek
OAKES, N.D. — The North Dakota Corn Growers Council and various corn seed companies are financing a study in Oakes, N.D., to determine how much corn stover can be removed for use in ethanol or biomass production and still maintain soil productivity.
The study employs strip tillage, a management practice that avoids tillage and leaves of as much plant residue as possible,” says Walt Albus, research agronomist.
“We’re growing corn-on-corn, and taking 0 percent, 33 percent, 66 percent and 100 percent of the stover off,” Albus says.
They’re comparing these results with corn-on-soybean rotations.
Albus and colleagues are collecting soil fertility information, especially focusing on nitrogen, phosphorus and potassium (NPK). So far, the stover removal has its biggest effect on potassium, as expected.
“We generally figure if we’re taking off a big corn crop we should be taking off 88 pounds of potassium,” he says.
At current fertilizer price levels, the study results so far indicate that removing 1 ton of stover per acre removes the NPK equal to at least $15 per ton of dry matter removed, or $81 per acre.
Any payment system to farmers for biomass has to add that to the payment to replenish the nutrients and keep the soil productive.
“We can’t look at that stover as trash,” Albus says. “It has a value for organic matter, and if we take the nutrients off we have to put them back.”
Similar corn stover studies are being done throughout the United States, but Albus says it’s important to do them here.
Data from other studies
Preliminary University of Minnesota studies so far indicate farmers can remove about 44 percent of the stover in corn-on-corn production, and be sustainable, he says. If it’s a corn-soybean rotation, farmers can remove about 16 percent of the stover and keep sufficient organic matter long-term, according to the early data.