Tag Archives: University of Kentucky

Annual Ryegrass – the Germ Seed of Cover Crop Adoption in the US Part 18

The Next Generation of Innovators in Agriculture

“There is no known abatement of fragipan,” said Dr. Phillips Phillips, a researcher with the USDA’s Agriculture Research Service (ARS) in Ames, Iowa. “Until now, that is,” she added. “Annual ryegrass is a good one, because the chemicals in ryegrass roots break down fragipan.”

Phillips and the congressionally-funded ARS are delving deeper into the mystery of why annual ryegrass has this effect on fragipan. She said there are 50 million acres of agricultural crop land impacted by fragipan in the U.S. alone. “And fragipans are a problem around the globe,” she added.

Phillips and colleagues have proposed work to follow that of Lloyd Murdock, who for the past decade has been documenting and testing the effect of annual ryegrass on fragipan in laboratory settings and in the field. Murdock’s research at the University of Kentucky found that a chemical exudate from ryegrass roots is the reason. Specifically, the chemical excretion from annual ryegrass roots systematically changes the chemistry and make-up of that compacted soil, effectively reducing the presence of fragipan. In the following graph, taken from Murdock’s study, you can see how annual ryegrass reduced the depth of fragipan and increased the depth of healthy soil in five locations in two Midwestern states.

Phillips is leading a five-year study on annual ryegrass’ effects and how to augment them. “A key part of our research will quantify how annual ryegrass, used as a cover crop, affects the amount and availability of water in the field,” she said. “By reducing fragipan, we may be improving drainage and thus expanding the window for planting in the springtime,” Phillips added. “And we think that reducing fragipan will make more soil water available during the summer too, by increasing root depth. We want to measure how much more available soil water is present, and whether the crop can put on more leaf area and experience less water stress.”

John Pike, a former University of Illinois ag research manager, will be monitoring the study in Illinois, funded by the Oregon Ryegrass Seed Growers Commission.

“Mike Plumer and other pioneers showed that annual ryegrass can be really useful in Southern Illinois, Missouri, and Kentucky,” Phillips said. “As our weather continues to change, ryegrass could increasingly be seen as a ‘climate adaption tool.’ Specifically,” she explained, “in the Midwest we’re having more rain in the spring, and the rain events are bigger. I hope annual ryegrass’ ability to reduce fragipan will allow more water to be absorbed into the field instead of running off. So, even with more rain, farmers will be able to get into the field in a timely fashion, simply because the water will infiltrate more quickly rather than pooling or creating erosion.”

“Additionally,” Phillips continued, “the month of July in the Midwest is becoming hotter and dryer than in the past. July is when the corn most needs moisture. Annual ryegrass, by helping to create deeper soils may be able to make up for that reduced precipitation.”

Phillips’s colleague, Dr. Dan Olk, will lead complementary studies on how annual ryegrass chemically degrades fragipan. Olk, a biochemist, is an expert on humic products, which are derived from young coal deposits and are thought to enhance plant growth. Hypothetically, humic products used in conjunction with annual ryegrass may have a compounding effect on the decay of fragipan and enhancement of crop health. Phillips and Olk will look at samples of fragipan soil collected from Kentucky and Illinois in different stages of degradation. “We want to find out how the chemistry of fragipan changes at different stages of breaking down, and whether humic products change the rate of fragipan disintegration,” Phillips said.

While Phillips is focused on the science and field work, John Pike will also be sharing the educational aspects of the work with a variety of audience, from field day demonstrations to trade shows. Phillips acknowledged the importance of a team approach to this and other projects. “I’m very thankful to those who are partnering with us in our efforts, like John Pike, the Oregon Ryegrass Commission, and Oregon seed growers, who continue their on the ground support for this work.” She also acknowledged Ryan Hayes, an ARS colleague who works on plant breeding at Oregon State University, where she worked before moving to Iowa in 2020.

Some worry about how the adoption of cover cropping and regenerative agriculture will keep expanding, as a generation of cover crop pioneers like Mike Plumer and Lloyd Murdock retire. It is refreshing to see the next generation of growers and scientists, like Phillips, stepping in to develop the place-specific knowledge necessary to make cover cropping work in a challenging environment where it can have the most benefit.

Kentucky Researchers Praise Annual Ryegrass

Annual Ryegrass Dispatches with Fragipan Problems, They Say.

Midwest  farmers who have been working with annual ryegrass for some years as a cover crop know that annual ryegrass busts up fragipan (and other soil compactions). They have probably seen for themselves how annual ryegrass as a cover crop then allows corn and soybeans roots to access deeper soil moisture and nutrients.That boosts production, as we’ve seen now for about 20 years.

Mike Plumer, a long-time pioneer in no-till ag and cover crop systems, discovered the deep rooting aspects of annual ryegrass back in the 1990s, when he was still working as an agronomist for the Univ. of Illinois Extension. He and his cooperating farmers also discovered that the roots grow right through compacted soils. In subsequent years, they noticed a yield increase in crops in those same fields.

In a recent article in No-Till Magazine, researchers at the University of Kentucky did both laboratory and field trials using annual ryegrass on soils with fragipan. Here are a number of paragraphs from that article.

Soil fragipans exist in 2.7 million acres in Kentucky and in 50 million acres in the U.S. In Kentucky, the average depth of the fragipan layer in the soil is about 20-24 inches. This results in a shallow soil that limits crops’ yield potential due to low water-holding capacity. This is especially true during dry growing seasons or droughts. These same soils are easily saturated with water in the winter, which limits yields on cool-season crops such as wheat.

 Breaking down the fragipan would increase the soil depth and should significantly boost grain yields in the state, similar to the boost farmers received from implementing no-till production.

Four years into the research project, Grove and fellow UK soil scientists Lloyd Murdock, Tasios Karathanasis and Chris Matocha have found that annual ryegrass and some chemical combinations appear to break down the fragipan.

 In the lab, Karathanasis submersed chunks of fragipan in several different solutions, one of which was a ryegrass extract.

“Within 2-4 weeks we began to see the ryegrass extract break down the fragipan,” he said. “Not only does ryegrass have a deep root system that can penetrate the pan, but it also releases a chemical or chemicals that can help break it.”

 UK soil scientists have planted annual ryegrass as a cover crop in grain fields followed by either corn or soybeans for the past three growing seasons with the fourth round now in the ground. The first year when annual ryegrass was followed by corn, there was no yield difference. The second year when it was followed by soybeans, there was a 25% yield increase in the soybeans. The third year, the researchers followed the ryegrass with soybeans again and there was a slight, but not significant, yield increase.

UK researchers traveled to Hamilton County, Illinois, to take soil samples from a field that had been planted in a ryegrass cover crop since 2000 and followed every year with no-till corn. Mike Corn roots in ARG 6-06 StarkeyPlumer had used a part of this field in some of his earlier cover crop studies.

They found the fragipan layer to be much deeper in the soil profile in the fields with ryegrass. More encouraging news came when the farmer told them about his yields.

“When the study started in 2000, the farmer’s yields were 15 bushels an acre below the county average. His fields are now averaging 30 bushels more per acre than the county average,” Murdock said. “We really do not know how well this field represents our situation in Kentucky, but this gives us significant encouragement that we are beginning to prove that annual ryegrass is effective and will give significant results with accumulative years of a ryegrass cover crop.”