Farmers using cover crops as a soil conservation method can remove much more corn stover per acre for biofuels or other uses and at the same time potentially increase their income, Purdue University research shows.
The research points to cover crops as a way to protect the soil and add value. Using cover crops like crimson clover or annual ryegrass, farmers can sustainably remove 1.8 tons more stover per acre than they otherwise would remove, the researchers say.
"The most important finding is that the added revenue from stover removal likely would be enough to pay the costs of a cover crop, in most cases," said Wally Tyner, one of the researchers. "Thus, with a cover crop, more stover removal is environmentally sustainable."
Return on planting cover crops
In addition to testing whether revenue from stover sales can pay for cover crop costs, the study also analyzed the benefits of different cover crops and cover crop mixtures for farmers who just reap the agronomic impact and for farmers who remove and sell corn stover.
"If you have a cover crop, it provides some of the same soil retention, organic matter buildup and other benefits as keeping the stover on the ground. In fact, it provides more," Tyner said. "So, if there were a viable market for corn stover for biofuels, animal feed or anything else, then the added stover that could be sustainably removed could provide enough revenue to pay for the cover crop costs."
As the U.S. government encourages a transition to biofuels, stover removal is likely to increase, Purdue says. By 2022, the U.S. Energy Independence Act requires that 16 billion gallons of ethanol-like biofuels come from renewable fuel sources. These could be derived from corn stover.
For farmers who remove and sell stover, the benefits are financial. Instead of increasing agronomic value, such as soil retention and vitality, the cover crop replaces the corn stover as a protector and preserver of the soil.
In turn, more stover can be removed and sold, then turned into biofuel. Considering cost alone, annual ryegrass provided the greatest potential profits in models, but when nitrogen in the soil was accounted for, crimson clover performed better.
But even farmers who don't remove corn stover may gain agronomic advantages from cover crops – healthier soil with more nutrients that is less likely to erode or compact.
For instance, crimson clover adds $21.28 worth of nutrients to the soil per acre and increases the soil organic matter by a value of $44.72 an acre. It reduces soil compaction and erosion as well, further increasing the value of the soil for the farmer, Purdue says.
View the full report, Synergies Between Cover Crops and Corn Stover Removal, which includes comparisons and benefit-cost analyses of six cover crops and two cover crop mixes for agronomic advantage or corn stover removal.
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