Cover crops crusader

Jim Stute has experimented with no-till and cover crops for nearly 30 years. His own 160-acre farm near East Troy, Wisconsin, has harbored his research, as have tests plots in farmers' fields and at the nearby Michael Fields Agricultural Institute, where Stute served as research director before becoming an independent researcher.

The knowledge he's gained over the years about the beneficial role of cover crops in no-till systems has made him something of a cover crop crusader. "My overarching goal is to improve soil health and water quality," he says.

"To do that, I'm trying to increase cover crop adoption among farmers and specifically on rented ground."

Besides boosting soil health, increased cover crop adoption can also help farmers fit into the emerging carbon economy.

Soil Health Hesitation

Stute's rationale is that improving the health of the soil on that rented land will go a long way toward improving soil and water in the bigger picture of resource conservation. That's because, out of all the land farmed in Wisconsin, 50% of the acres are rented from landowners, Stute explains. He believes farmers hesitate to commit to building soil health on these rented acres.

"Why would farmers invest in long-term soil health on ground they could lose in three years, if the landowner decides to rent to someone else?" he asks. The answer to that question lies in economics. Demonstrate the cost-effectiveness of soil health practices, he believes, and farmers will embrace them. To that end, Stute has worked to show the economic benefits of implementing no-till in combination with growing cover crops.

An on-farm analysis with the support of a North Central Sustainable Agriculture Research and Education grant did just that. Working in partnership with five Wisconsin grain farmers, Stute collected data from on-farm, side-by-side test strips to determine the impact of cover crops on crop yields and bottom lines. Stute used partial budget analysis, factoring in all additional costs and returns, to determine the effect of cover crops on farm profitability.

He found that cover crop use increased average corn yield by 2.1% and average soybean yield by 2.3%.

At the input costs and low commodity prices at the time of the study, which ran from to 2016 to 2019, break-even yield increases were 5.5% for both crops.

The economic data shows only a partial view of the potential benefits farmers stand to gain by growing cover crops. Crop resilience in drought years is an added bonus.

Drought Impact

In the drought year of 2012, Stute looked at the effect of a previous cover crop on corn yield. He analyzed the effects on corn of a red clover cover crop in a field of winter wheat on his farm. He frost-seeded the clover in the wheat in March 2011 and terminated it in November.

The following spring Stute no-tilled corn into the mat of unharvested wheat straw and clover residue. "With row cleaners, the planter leaves 70% to 80% of the residue undisturbed, to conserve soil moisture later in the season," he says.

July rainfall at this location was 4.76 inches. "The residue increased infiltration and reduced evaporation, which helped lessen the yield impact of the drought," he says.

The corn grown in the previous year's clover cover crop yielded 135 bushels per acre (bpa), which was 79% of the farm's three-year mean yield of 170 bpa. By comparison, the county-wide average corn yield for that drought year was 102 bpa, or 62% of the three-year county average corn yield of 164 bpa. Reducing the loss of soil and its attendant nutrients is yet another benefit farmers realize from adopting no-till and the planting of cover crops. The economic losses from soil erosion may be hard to quantify, but losses in crop productivity and an increasing need for purchased fertilizers come hand in hand with erosion.

"Long-term soil degradation is real, and it should be a concern for farmers," says Stute.

Data he has compiled for groups working to clean up watersheds, including the Watershed Protection Committee of Racine County of which he's a member, shows how the adoption of conservation practices can dramatically reduce the amount of sediment and nutrients potentially leaving farmers' fields and draining into watersheds.

Estimates from SnapPlus, the University of Wisconsin's nutrient management planning software, indicate that sediment loss from conventionally managed cropland in southeast Wisconsin frequently exceeds "tolerable" levels. Yet when farmers adopt the use of several conservation practices used in combination with each other, they can significantly reduce the soil loss. "On ground where farmers have adopted no-till, planted buffer strips, grown cover crops, and planted cash crops into green covers, sediment loss from both corn and soybean fields is cut by nearly 75%, with accompanying reductions in phosphorus loss, depending on soil test levels," he says.

Paradigm Shifts

Stute's decades of experience on his farm have brought paradigm shifts over time. He started farming in 1994, adopting cover crops from the get-go. He grew corn, soybeans, and winter wheat, planting a cover crop behind the wheat. But he held to the practice of tilling some of his fields, no-tilling soybeans and wheat, but using conventional tillage in corn. "My primary motive then in growing a cover crop was to have green manure to work into the soil," he says. "It was my understanding then that tillage was necessary in order to get the benefits of the nitrogen supplied by the cover crop. But I later learned that wasn't the case. We don't need tillage in order to get the N credit from cover crops."

Eventually he stopped growing winter wheat because he found it hard to get the soybeans custom harvested in a time frame permitting timely wheat planting. He then planted a cover crop after soybeans — a necessary practice, he reasoned, considering soybeans' reduced surface residue after harvest.

"But I was dubious about planting rye after corn," he says, "because corn itself leaves a lot of surface residue after harvest. But my work with farmers changed my mind. Rye's best effect is in the spring. It gives a tremendous opportunity to produce biomass that benefits the soil. It also helps to suppress weeds and scavenges residual N that the corn crop didn't take up. It's important to keep N in the soil system in order to prevent off-farm movement of the nutrient. Planting a cash crop into a green cover, thus delaying termination, helps extend the time frame that we have to realize benefits from the cover crop."

Carbon Market Fit

As carbon markets and ecosystem markets advance, offering economic incentives for farmers to adopt practices that conserve soil and sequester carbon, Stute envisions the evolution of farming systems embracing multiple conservation practices. "It's a many-little-hammers approach where practices will work together in a cropping system to improve soil health, improve water quality, and reduce input costs for farmers," he says.