Tag Archives: Dr. Claire Phillips

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.

The Germ Seed of Cover Cropping in the US – Part 14

The Chemical in Ryegrass that Crumbles Fragipan

The hunch that annual ryegrass use was breaking down the fragipan at Junior Upton’s farm in Illinois was like music to Lloyd Murdock’s ears. The University of Kentucky (UK) research team had begun to experiment with different chemicals in the greenhouse and field where he worked at the University of Kentucky’s Princeton farm and in the lab on the main campus.

While they waited for results on field plots of annual ryegrass they planted that year, the UK research team began working with the plant in controlled lab and greenhouse environments. They created extracts made from annual ryegrass roots, as well as from the foliage. “Naturally cemented fragipan clods were placed in a solution of annual ryegrass extract. Thirty days later the size and distribution of the remaining aggregates were determined. As the binding agent in the fragipan is dissolved by the chemical, the fragipan clod begins to fall apart. The greater the dissolution of the binding agent, the smaller the remaining aggregates.  Ag related chemicals were also tested but it was annual ryegrass that demonstrated the most significant ability to dissolve the cementing agents biding the fragipan particles,” he said.

Lloyd also made numerous trips to visit Junior’s farm in those years, to authenticate what they were experiencing there, and to apply what was being gleaned. “We’ve known, for example, that some plants do not exert much pressure at the root tip. Annual ryegrass roots tips, on the other hand, exert a high amount of pressure,” Lloyd said. “So those roots will seek out a crack or weak spot in the fragipan and break through there. It doesn’t take many roots getting through to make a difference. And when corn roots follow those same channels the following year, they’re getting access to nutrition and moisture below the fragipan,” he added. The combination of plant chemistry and root pressure has a dramatic effect on fragipan.

The UK team did replicated trials in five Kentucky and Indiana sites. Below, Table 1 shows, in controlled studies, annual ryegrass reduced the thickness of fragipan significantly at each site, allowing more soil depth for crops.

Dave Fischer is a beef producer from Indiana, and it is his Debois County farm mentioned in the table above. Fisher has planted annual ryegrass on his farm for the past eight years. “When I visited his farm last year, I found that he had lowered the fragipan depth by 14 inches and had annual ryegrass roots 29 inches deep,” Lloyd said.

“Those results floored me,” said Fisher in a video on the project. “But at the same time, I had noticed that these fields seemed to not dry out as fast compared to what they used to and to neighboring fields. We were hanging in there a lot longer during drought periods,” he said. “I would plant it just because of the forage, but the addition of breaking up the fragipan has just been super.”

“I’m more excited about this research than any other project I’ve worked on in my 45 years at the University of Kentucky,” Lloyd said in a University news article, “because it can help so many people. It is something that farmers can work into their operations now to increase their yields.”

As he prepared to retire once again, Lloyd said he has been grateful for the Oregon Commission, and others, whose support was crucial for the UK team’s work on annual ryegrass research. “And it looks like others who have noticed our work are picking up where we’ve left off,” he said with a smile. “Claire Phillips, who received her PhD from Oregon State University and has been a soil scientist for the USDA in Iowa for six years, as well as Dr. Dan Olk and Dr. Dana Dinnes are interested in continuing the work we began. And, likewise, John Pike, an agronomist at Southern Illinois University, has also expressed interest in helping to further the research of fragipan and to continue promoting the use of annual ryegrass as a cover crop.”