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Iowa State Scientists lead quest for perennial cover tailored to conventional cropping systems

Posted Jun 22, 2023

Iowa State University researchers are leading a quest to develop a farming system that integrates cash crops with a cover crop that would only need to be planted once every five to 15 years. It’s a tall order, but one the research team thinks can soon be realized.

The project goes by the name, RegenPGC, short for Regenerating America’s Working Landscapes to Enhance Natural Resources and Public Goods through Perennial Groundcover. The large team of scientists and engineers all share a vision of seeing year-round cover on cropland in the Midwest become the norm rather than the exception.

“We want to develop groundcover systems, where a perennial cover crop is planted once and then persists for multiple years alongside annual crops. The cover crops would be alive during the six to nine months when fields are often bare between harvest and planting, yet would pose little or no competition to the cash crops.” said project leader Raj Raman, Morrill Professor of agricultural and biosystems engineering at Iowa State.

“If we’re successful, we believe this could encourage more widespread adoption of cover crops to reduce the unintended consequences of conventional cropping systems in a way that is convenient and low-cost for farmers,” he said.

Like regular one-season cover crops, the most evident benefits of perennial groundcover would be to protect and enhance soil, reduce nutrient export into water and enhance the potential for carbon sequestration. There could be some weed or insect suppression effects, leading to reduced need for herbicides or insecticides, Raman said.

There might also be harder-to-anticipate advantages, Raman said. For example, in 2020, there were anecdotal reports that corn growing in perennial test plots stood up better to high winds than corn in adjacent, conventional plots. Researchers hypothesized that the corn’s reduced “lodging” in the test plots could be due to improved soil health that led the corn to develop a more robust root system.

Experiments led by RegenPGC team members Kenneth Moore and Shui-zhang Fei set the stage. Moore, a Charles F. Curtiss Distinguished Professor in Agriculture and Life Sciences at Iowa State, and Fei, professor of grass genetics and breeding in horticulture, have tested more than 30 perennial species for compatibility. They found that some perennials grew and provided ecosystem benefits without sacrificing crop yields – but only under ideal circumstances.

The group’s primary goal now is to find the perennial that will work reliably under the varied conditions farmers face across years.

  • Will the cover crop candidate survive through multiple seasons yet go dormant in time for corn or soybean planting?
  • If the perennial doesn’t go dormant at the right time, what will it take to suppress so it won’t compete with the primary crops during the growing season?
  • If the perennial works under field conditions in Iowa, what about drier climates in Nebraska or Kansas, or colder temperatures in Wisconsin?

On their quest, the team is conducting field research and computer modelling, backed by a five-year, $10 million grant from the USDA National Institute of Food and Agriculture’s Agriculture – Food Research Initiative that started in 2021. Earlier funding from the Iowa Nutrient Research Center supported the field trials by Moore and Fei that provided a nucleus for the larger grant, Raman said.

Almost a dozen other Iowa State faculty, staff and graduate students are working on the new RegenPGC project, along with counterparts at universities in Kansas, Kentucky, Missouri and Wisconsin. Other research and commercialization partners come from The Land Institute in Kansas and Corteva Agriscience while Iowa 4-H and FFA are involved in the project’s wide-ranging education programs.

“Perennial groundcover systems offer a viable pathway for the near-term perennialization of annual row-crop agriculture that complements The Land Institute’s long-term work to create perennial grain crops,” said Brandon Schlautman, RegenPGC’s research theme director and a lead scientist with The Land Institute.

The project also aligns with Corteva’s mission to help farmers sustainably grow food, fuel and fiber, according to Sara Lira, RegenPGC’s commercialization theme leader and a senior research scientist with Corteva Agriscience. “Public-private partnerships are critical to solving the big challenges in agriculture, and we’re thrilled to bring our expertise and support to make this vision for year-round green cover on farms a reality.”

“With perennial groundcover, farmers can continue to leverage the amazing yield gains made through corn and soybean breeding and agronomic research, while also protecting the environment on their farm, in their community and downstream,” she said.

This summer, the team expects to further narrow down the list of perennial species worth studying. Top candidates at this time include varieties of Kentucky bluegrass and a species called Poa bulbosa, which goes dormant based on daylength.

Many of the test plots are on Iowa State research farms in central and northeast Iowa. There are also research sites in Kansas and Nebraska and about 20 on-farm trial sites where farmers are testing perennial groundcovers systems.

Several scientific publications have already come from the effort. They are listed on the RegenPGC website, along with upcoming field days and a form farmers can use to indicate interest in participating in field trials.

“If we succeed in developing a perennial groundcover system that works, we also need to make sure it works within the policy context that constrains farmers’ choices,” Raman said. “Crop insurance is central to that, as is working with ag retailers to provide affordable seed. Members of our team are already starting to engage on these next steps.”