Cover Cropping: A Locally Grown Innovation


For a craft as old as civilization itself, farming exists in a constant state of change as new technology and techniques become available.

As a state teeming with farmers, Iowa finds itself at the center of this process, constantly exploring new techniques and technology that provide more food for today’s world while conserving land for future generations to do the same.

Cover cropping, one of the latest leaps in agricultural practice, has received special attention locally.

The practice involves planting a non-cash crop, usually cereal rye, after the growing season and often without intent to harvest it. These crops remain in place through the winter, providing soil structure and eventually nutrients for the next crop come spring.

Though the practice has existed for generations, it has only recently entered the spotlight. Those using cover crops say they drastically improve soil quality and curb erosion, both noteworthy upsides for farmers who do it right.

Getting anything wrong, however, can spell disaster. Farmers worry about crop failure through disease, competition and insects, among the handful of risks associated with cover cropping.

Nevertheless, the practice has seen steady growth in Iowa, especially Washington County, over the last two decades. A handful of innovators, willing to take the initiative and the risk, have worked hard to optimize cover crops on all fronts, from the field to the classroom.

City of Riverside applies principles of cover crops


Outside of the controlled farming environment, cover cropping is a simple and effective way to maintain soil quality.

The city of Riverside recently employed the technique after an ITC Midwest transmission line project involved the removal and replanting of forest fauna several months apart, a move that would typically risk soil erosion in the interim.

“The City of Riverside asked our help in removing ash trees that needed to be taken down,” Rod Prichard, a spokesperson for ITC said. “In the spring, early summer time period, we planted rye and several different varieties of (local grasses) to hold that soil in place.”

Prichard said the grass would provide soil structure until fall, when more scenic fauna like prairie grass, trees and shrubs can be planted without risking soil loss in the interim. The process has been ITC Midwest’s standard procedure for reforestation measures since it was created in 2007.

“It grows quickly, it puts a nice cover down and it controls that erosion that takes place right after a project is over,” Prichard said. “The rye is short term, and then we come back in with longer term native fauna.”

Though the ground cover grasses included rye, Prichard said a mix of other species was needed to maintain biodiversity.

“Instead of strictly rye, the Riverside Trail Committee had requested that we plant any areas where dirt was exposed along the trail due to the construction process with a native grass seed mixture to match and be compatible with the vegetation that is already growing,” Prichard said. “The Trail Committee wants to see how it looks before final vegetation restoration – including planting of some shrubs and trees – takes place this fall.”

Professor finds problems and works on solutions


Using cover crops to hold soil together is simple enough for aesthetic purposes, but applying the technique to farm production requires more careful planning and data.

That data must first be recorded and shared by someone with extensive knowledge in the field. Alison Robertson, an Iowa State professor who holds a doctorate in plant pathology, is one such expert.

Robertson said her interest in cover crops started with a study in which she proved a link between rye cover crops and corn harvest shortfalls.

“With corn planted after a cover crop of cereal rye, sometimes you see a yield drag,” Robertson said. “One of the ideas that we had was that it may be due to seedling disease… organisms that cause seedling disease in corn live on rye.”

While seedling disease was the starting point of Robertson’s studies, she said cover crops carried a multitude of other risks.

“When the rye cover crop is decomposing, a lot of the nitrogen is immobilized and that means the corn seedling doesn’t have any nitrogen to take up,” she said. “The rye plants also release chemicals that are toxic to the corn. We also find that rye biomass left on top of the field can keep the soil temperatures cooler and wetter which can also lead to more disease.”

Though her research may seem skeptical of cover crops, Robertson said her ultimate goal was to improve the practice, not discredit it.

“I also understand the value of cover crops, for nutrient recycling, protecting our water quality, protecting the soil, etcetera,” she said. “We are focused on trying to find solutions, but to find the solutions we have to understand what the problem is.”

Isolating the problem of rye-linked microbes led Robertson to a field-shaping solution: waiting to plant. After the rye is killed off, the organisms associated with it soon follow, having no host sustain them. Robertson found that soil holding rye goes from dangerous to harmless for corn seedlings in a matter of days.

Though her work is highly specialized, Robertson is careful not to let herself get held up with academics. She said her connection to farmers was not only helpful in putting her work to good use, but essential to testing it in the field.

“Working with colleagues at Practical Farmers of Iowa and Iowa Soybean Association gets me onto the farms to work with farmers,” Robertson said. “We also have an on-farm component, we’re up to 200 farms, and maybe more, across the US where we’re actually working with farmers and collecting data and stuff like that, so it’s not so ivory tower.”

Company runs the numbers, takes the risks


At a test site in Ainsworth, a company called Continuum Ag gives the newest ideas in cover cropping trial runs, then sells the results to farmers and agriculture companies around the world who put it to use.

“We built an online software to map out the information,” Continuum CEO Mitchell Hora said. “Farmers are paying us to give them advice consulting.”

Hora said cover crops were becoming increasingly affordable thanks to state aid and rising popularity, but that farmers often held back because of planning issues.

“What we see with farmers is they’re figuring out how to make it economically work, but it’s also how do you logistically make it work,” Hora said. “Not all farmers are taking advantage of them because they don’t know how to do it.”

Hora’s business runs a variety of tests with cover crops, the most groundbreaking being relay cropping, a technique in which cereal rye and soy are grown at the same time in the same soil. Conventional practice, in contrast, leaves the rye in the ground through winter and kills it off in the spring.

The revolutionary approach could substantially increase farmers’ incomes and offset nitrogen imbalances infamously associated with soy farming.

“With this cover crop and this cash crop growing together, they obviously compete with each other if you do it wrong,” Hora said. “But you saw our soybeans that are growing in the rye and they look phenomenal because it’s a grass and a legume working together. The soybeans are fixing nitrogen, the rye is pulling nitrogen out of the soil, and they’re able to work synergistically together.”

Relay crops aren’t the only groundbreaking work happening at Continuum. The company tests a variety of harvestable cover crops and even alternative cash crops like malt barley and mustard.

“One of the principals of soil health is diversity, and that’s one of the tougher ones to do,” Hora said. “It’s opening up more opportunity to remain profitable because corn and soybean economics right now are terrible, but by coupling together barley and rye and mustard economics, we can make it work a lot better.”

Being at the cutting edge is an inherently risky business, but Hora said Continuum was structured with those risks in mind. Using test trials as an alternative, upfront income source allows the company to take gambles traditional farmers can’t afford.

“All the infrastructure, all the equipment, all the help, it’s all set up for corn and soybeans, so doing anything outside of that, you’re throwing off the system,” Hora said. “But we’re willing to try it because we’re reducing the risk upfront. Some of these things that are unconventional, the rye, the mustard, the barley, but we have a plan for it ahead of time.”

Local farmers put the practice to work

Washington County

The gauntlet of rigorous experimentation and testing has one ultimate goal: to ensure that only the best ideas make it to the farmers who put them to use for a living.

Washington County is a hub for these farmers, and has made waves as a hot spot for cover cropping.

“No-till is probably a little more predominant in this area than other parts of the state, it gets a little more attention, as do the cover crops,” said Steve Berger, a Wellman farmer whose no-till farm is 100% cover-cropped with cereal rye. “We think the system works really well. It improves our farm production, we think it improves our corn and soy yields, and we can do a little to help maintain the soil for the next generation.”

Berger is a veteran of cover crops, having first used them in 2000. His 2,200 acre farm has been called the “poster child” of soil sustainability by the Des Moines Register, but he said he understood the relatively slow adoption of the technique.

“If it were easy, everybody would do it… the adoption is slow so what that tells you is there can be somewhat of a steep learning curve to planting corn and incorporating cereal rye,” Berger said. “Corn doesn’t like competition, corn likes to be by itself in a nice, tilled field, so when you add a cereal rye cover crop, you’ve got to change your management system a little bit and that requires some thought, it requires some planning, it requires some capital investment in machinery.”

While the hurdles are challenging, Berger said the payoff was worth it with enough patience and careful planning.

“Once you get onto it, it actually is easier because you’ve got fewer trips to the field... but you can’t just go out there and say ‘I’m no tilling,’ it doesn’t work that way,” he  said. “You’ve got a time factor involved with that, you don’t have immediate value right away, and that’s the frustrating part.”

In Richmond, George Schaefer has operated a no-till farm with nearly 100% cover cropping for 15 years. While the overwhelming majority of his cover crops are rye, Schaefer said he had explored other options.

“Cover crops need to move in a new more evolved way to multiple species. Cereal rye is used most because it’s the easiest thing to work with and it creates a huge amount of biomass,” Schaefer said. “You can use clover, you can use oats, some people consider alfalfa to be a cover crop… Turnips are really good if you can get them in the ground in August, but that’s really hard to do.”

Schaefer acknowledged the difficulty of transitioning to sustainable farming, but said there were ways to simplify change.

“If you haven’t done it before, do it before soy beans, meaning you put the rye out there in the fall after corn,” he said. “You no-till into it, and that is the best way to start, the best way to learn, and that is a no-brainer… There’s actually a two to five bushels per acre yield increase from cover crops to soy beans.”


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