Create a field of agronomic dreams with on-farm trials

Depending on the field, cover crops can reduce soil erosion and compaction, improve water infiltration and storage within the soil profile, increase weed and pest suppression, and enhance nutrient cycling. Even though the regenerative approach can provide a wide range of benefits, only about 4% of U.S. cropland is planted with cover crops, according to the latest ag census.

• READ MORE: From seed to soil, cover crops amplify the benefits to the farm

“I think there is this myth about cover crops that needs to be busted,” says Iowa farmer Clint Luellen. “In our area, people think they are a waste of money, and no one has any data to prove otherwise.”

Misconceptions about cover crops, says Thomas Fawcett, are caused in part by the fact that it’s not a straightforward system.

“Like any new practice or technology, it’s not a perfect system. You must understand that going in. There will be failures, but what’s great about cover crops is that they have effects both in the field and downstream,” says Fawcett, director, environmental resources and precision ag, at Heartland Co-op. “You also have to look at cover crops as a long-term investment.”

On-farm trials demonstrate benefits

Through Conservation Innovation Grants (CIG) funding, Truterra and the Soil and Water Conservation Society are hoping to change that perception. The overall project is helping four ag retailers in Iowa, Kansas, and Nebraska set up large-scale, multiyear on-farm trials to demonstrate the benefits of a systems approach to precision management practices. By routing funding, advice, and monitoring to producers through their local co-op, the project aims to increase producers’ knowledge of conservation practices, integrate conservation management programs into retailer services, and broaden and accelerate conservation practice adoption. The subsidized trials equip participants with a team of specialists, software for evaluating results, and financial incentives to determine what practices work best on their farm. If successful, the project will become a model for others.

Two types of trials are offered. The first option is zone nutrient management, which implements a suite of practices including grid soil sampling, variable-rate fertilizer applications, split applications, nitrogen stabilizers, and in-season tissue testing. The second trial focuses on cover crop management.

The trial’s goal is to evaluate the effect on yield and profitability when planting a cover crop vs. conventionally managed acres.

The Truterra sustainability tool is being used to collect and measure findings.

Because marrying technology with conservation practices was already a topic being discussed at Luellen Farms, participating in the cover crop innovation trials through Heartland Co-op made sense.

“This trial is an opportunity for us to dive into the data of what’s really happening on these fields, so we can make better management decisions in the future,” Luellen says.

As part of the CIG project, all the Iowa acres (989) enrolled in the program through Heartland Co-op were assessed for their use of cover crops. According to the Truterra sustainability tool, 8% of the acres were identified as using cover crops in 2019. (See map.)

Participating acres using cover crops in 2019. Yes (green) | No (blues).

“There is a significant opportunity to promote cover crops as a stewardship practice that helps with nutrient management and soil health,” Fawcett says. “Using Truterra’s data analytics and modeling tools, we can work with Clint to model the impacts of adopting cover crops and determine if this practice makes sense from an environmental and profitability perspective, field by field.”

Luellen is required to designate two 80-acre fields (a trial field and a control field) to the project for three years. He chose fields he rents from Harold Hill with similar soil attributes and yield trends.

Of the nearly 30 million acres of Iowa land dedicated to growing crops, close to 60% of those acres are rented, according to an Iowa State University Farmland Ownership Tenure survey. Both Luellen and Hill believe talking about the environmental and stewardship practices that need to be implemented is an important part of the renter-landlord relationship.

“My initial goals were to learn about the possible benefits of cover crops and the possible problems on this ground. I was more interested in improving soil tilth and minimizing nutrient loss than maximizing profit,” Hill says. “Once that soil tilth increases, I also want to understand how it impacts water infiltration rates while still maintaining yields.”

Evaluating year one

Even though the first year of the trial was dry, Luellen had 60 pounds of cereal rye applied to the trial field along with dry fertilizer on October 20. 

Given how dry it was that fall, Hill worked the cereal rye into the soil with a Case IH Barracuda to give it a chance to germinate. “Harold was just scraping the surface — with about a 1-inch soil penetration — to break down the corn stalks and essentially get the seed incorporated,” Luellen says. “We talked about it multiple times afterward and hoped we had made the right decision.” 

Although the field was short on moisture, Luellen says the cereal rye popped more than a lot of cover crop fields do. “It looked amazing. The amount of people calling wondering what we did or how we did it was incredible. Many had never seen a stand half as good.”

• READ MORE: 3 complementary strategies for raising crops and cattle

What you’re seeing above ground, he notes, is doubled below ground. “Those cover crop roots are going deep into the soil, and the corn or soybean plant follows that cereal rye root,” Luellen says, adding that they did a good job of breaking up compaction. “It made me excited for a year when there is adequate moisture.” 

In the first year, they learned that getting the cereal rye on the ground and germinated as soon as possible after harvest is critical to getting a beneficial stand before winter. 

“We also realized that in a dry spring prior to planting, especially soybeans, the rye can dry the surface moisture out much more than without the seeding, placing the germination of soybeans at great risk,” Hill says. 

Because of heavy soil, growing soybeans is tough in their area, Luellen adds. On average, they yield about 45 bushels per acre. Corn sees more success. “On average, the trial field yields about 210 bushels per acre. I think this ground is capable of 250 bushels per acre,” he says. 

Although cover crops don’t seem to make much difference in a dry spring in terms of workability, Luellen says, “In a wet spring they have allowed us to get into fields earlier and easier even when a majority of our other acres are unfit.”

The cereal rye is also keeping weeds at bay. “Because the rye is terminated in the spring, we don’t notice the early pressure of weeds like we have in previous years,” Luellen says. 

The land also receives a Truterra sustainability score, which is basically a credit rating (on a scale of 1 to 100) of the overall stewardship for that field. This score includes an assessment of the mix of agronomic and conservation practices that are protecting and enhancing soil, water, and air resources. 

“The trial field scored an 80. If the field were under conventional practices, it would have scored a 19,” says Will Hoffmann, conservation agronomist at Heartland Co-op. “This means they are greatly reducing emissions, increasing soil organic matter, and saving 2.61 truckloads of soil erosion from leaving their field.” 

“If we can help growers improve the stewardship of their farm and see success in adopting conservation practices, it strengthens our relationship,” Fawcett says. “A project like this can also help us demonstrate to farmers that rather than see a practice or a technology as an expense, it can be an avenue to bring dollars back to the farm.”