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Does Planting Green Into a Rye Cover Crop Affect Corn Growth And Yield?

By Dr. Alison Robertson and Jyotsna Acharya

As more producers integrate cover crops into their operation, there has been increased interest in planting corn into a green or living cover crop, such as cereal rye, and terminating the cover crop after planting.

To help provide some insight into how “planting green” might affect corn growth and yield, we did an experimental field plot study comparing the effect of termination date of a winter cereal rye cover crop on growth, development, seedling disease and yield of corn in 2019 and 2020.  This research project is being funded by USDA-NIFA through the Critical Agricultural Research and Extension program.  Below is a summary of what we learned.

We looked at terminating the cereal rye cover crop 18 and 3 days before (DBP), and 6 and 12 days after planting (DAP) corn (Fig. 1.) Cereal rye biomass in 2020 was almost double that of 2019. In both years, corn seedlings were taller and shoot dry weight was less in the treatments where cereal rye was terminated after planting the corn (Table 1). In 2020, the corn seedlings in the treatments where cereal rye was terminated after planting the corn were approximately half a growth stage behind the no cover crop control and the treatments where cereal rye was terminated before planting. Radicle rot was more severe in the treatments where cereal rye was terminated after planting the corn compared to the remaining treatments. Yield was lowest when cereal rye was terminated 12 DAP corn.

field plots

Fig. 1.  Photo of field plots to investigate the effect of planting corn into a green cereal rye cover crop near Boone, Iowa.

Table 1. Effect of termination treatments of a winter rye cover crop on corn seedling growth, root disease at growth stage V2 to V3, barren plants at R6, and yield in Iowa.

Effect of termination treatments

These data suggest that planting corn into a green cereal rye cover crop may contribute to seedling disease, and negatively affect corn growth, development and yield. To mitigate risk, we continue to recommend terminating a cereal rye cover crop 10 to 14 days before planting corn.

We are continuing to investigate the effect of planting green on corn.  As part of this project, we are working with Practical Farmers of Iowa to collect on-farm data on planting green.  In addition, Iowa is one of 15 states investigating the effect of planting green on weeds, insects, diseases, and corn development and yield from 2021 to 2023 as part of a USDA-NIFA CAP project being led by Steven Mirsky at USDA-ARS BARC, Maryland and Chris Reberg-Horton from North Carolina State University.

Source : iastate.edu

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Canada is trying to decide how much agricultural research capacity it can afford to lose. Brian Rossnagel believes the better question is whether the country can afford to rebuild it.

The longtime barley and oat breeder makes the case with a simple fact about his profession: the consequences of today’s decisions may not become visible for 10 or 15 years.

“Pick the right parents. That’s the biggest thing,” Rossnagel says. “If you pick the wrong parents, you’re not going to get anywhere—and you don’t know that until 10 years, 15 years later.”

That warning carries particular weight as Agriculture and Agri-Food Canada moves to reduce spending and streamline parts of its science operations. The department’s 2026–27 plan anticipates the loss of approximately 665 positions by 2028–29 and says some research will be reduced where capacity exists in academia or industry. AAFC says the changes will make its science operations more cost-effective over the long term.

For Canada’s seed industry, Rossnagel’s career illustrates what is at stake.

This fall, the retired University of Saskatchewan breeder will be inducted into the Canadian Agricultural Hall of Fame. During his 35-year career at the Crop Development Centre, he helped develop more than 100 barley and oat varieties, including CDC Austenson—one of Western Canada’s most widely grown feed barleys. His induction recognizes not only those varieties, but the collaboration and research system that made them possible.

Rossnagel is quick to emphasize that none of it was the work of one person.

“The first thing I thought about was all the other people who contributed to whatever success I and my program had over the years,” he says. “We know that it’s not an individual who does this. It’s a group—a team.”

That team extends well beyond the breeder whose name appears beside a variety. It includes technicians, pathologists, quality specialists, statisticians, regional testing sites, seed growers and industry partners. It also includes the breeders who came before and those who will carry the germplasm forward.

CDC Fraser barley, for example, moved through three breeding careers. Its parents came from Brian Harvey’s program. Rossnagel advanced the material after Harvey retired, and Aaron Beattie later guided it through registration and release.

That kind of handoff is normal in plant breeding. The person who makes the original cross may never see the resulting variety reach farmers.

It also explains why lost research capacity cannot simply be switched back on when budgets improve.

“If you shut it off, it’s very, very difficult—and particularly costly—to start it up again,” Rossnagel says. “If you have to start from scratch, it’s going to be at least 10 years before anybody notices whether you’re getting anything done or not.”

The concern is not simply how many experimental lines Canada can process. Modern equipment, statistical tools and genetic technologies allow today’s breeding programs to evaluate tens of thousands of lines—far more than Rossnagel could handle when he entered the field in the early 1970s.

But efficiency and automation do not generate every idea.

“If you pare back down, and instead of having six or seven individual scientists concentrating on wheat breeding, you go down and say three people could handle all this, well, that’s half the ideas gone,” he says. “Particularly if you happen to lose the three people who had the really neat and innovative ideas, boy, that’s a problem.”

It is a timely distinction for Canadian agriculture. Consolidating programs may preserve the volume of material moving through a system, at least initially. It may not preserve the diversity of thinking, regional knowledge or willingness to pursue unconventional crosses.

That regional knowledge matters because Canadian agriculture is not one uniform production environment. A variety suited to southern Alberta may face different disease, moisture and maturity pressures than one grown in Manitoba, Ontario or Atlantic Canada.

“Agriculture is applied biology,” Rossnagel says. “Biology, all around the Earth, moves from the poles to the equator. It does not move from Newfoundland to B.C. like politics do.”