Tag Archives: University of Kentucky Agriculture

The Next Wave of Annual Ryegrass Research at USDA

Dan Olk went to the Philippines after earning his PhD at UC Davis, accepting a post-doctoral position with Dr. Ken Cassman at the International Rice Research Institute. They were investigating a global problem with declining rice productivity. “The plants were making use of fertilizer nitrogen but not soil nitrogen, despite the abundance of nitrogen in the soil,” he said. After years of study, they developed a winning strategy. By changing the seasonal management of rice crops and aerating the soil when the crop residues were decomposing, the trapped nitrogen could be released from organic matter. A few years later, a comparable project in Arkansas rice confirmed these results.

After joining the USDA in Iowa in 2001, Dr. Olk’s sleuthing continued to reveal why nutrients get bound up in soil chemistry, for rice growers internationally as well as domestic corn and soybean producers. Beyond his efforts to unleash the potential of organic matter, Olk has also spent many years investigating the use of “humic products” (made from young coal deposits) and their ability to stimulate plant growth.

Humic Products News

The annual ryegrass cover crop project in the Midwest had been rolling along for more than 15 years when it came to Olk’s attention through the work of Dr. Lloyd Murdock, who had been researching the effect of annual ryegrass cover crops on fragipan soils located in Kentucky and Indiana. Olk and his USDA colleague, Dana Dinnes, were presenting a seminar on humic products at the 2016 National No-Till conference. Murdock was receiving an award at the same conference, and that’s when the men met. Murdock was being honored for his decades of research on no till, which shows tremendous potential for boosting agricultural productivity and soil health.

Because fragipan, a nearly impermeable layer of compacted soil, is so pervasive in the US (50 million acres), the USDA has become interested in putting some of its considerable heft behind this new discovery. Dr. Olk will lead a new research project that will pick up where Murdock’s work at the University of Kentucky left off.

If you’re new to the story, here’s a quick summary: Junior Upton, working on his southern Illinois farm for decades, discovered in the 1990s that annual ryegrass added value to marginal land under which fragipan lay. Before trying annual ryegrass as a cover crop, Junior noticed that corn roots would grow down only to the edge of the fragipan layer (18 – 24 “deep) and then deflect sideways, unable to penetrate.

But when corn in the fields covered by annual ryegrass began to outproduce neighboring fields, especially in drier years, he asked agronomist Mike Plumer to help him understand why. Plumer, then at the University of Illinois Extension, came out with digging and soil coring equipment. In four-foot soil pits, they discovered annual ryegrass had exceedingly long roots that grow throughout the winter, even with scarce top growth. That was their first “aha!” The second one, which now has the USDA’s interest, is that ryegrass roots pierced the compacted soil and, thus, gave corn plants more rooting depth, additional nutrients, and moisture. With that encouragement, Junior planted annual ryegrass on his entire farm, year after year, and his soil health continued to improve as row crop yields increased. When he first planted annual ryegrass and began collecting data on corn production, his corn yield was 15 bushels per acre (bu/ac) below the county average. In 2020, after 20 years of continuous no-till and annual ryegrass, the same field produced 30 bu/ac more than the county average.

Murdock heard about Junior’s and Plumer’s discovery and spent more than five years documenting what they were seeing in Junior’s fields, as well as replicating field trials in four other farms in three states. Murdock and his university team also took the experiments into greenhouses and their laboratory to find out more about the chemistry and mechanics – trying to understand why annual ryegrass seemed to degrade fragipan, where nothing practical and sustainable was found to do that in the last half century of research. His lab partner, Dr. Tasios Karathanasis, submersed chunks of fragipan in several different solutions, one of which was a ryegrass extract.

“Within two to four weeks we began to see the ryegrass extract break down the fragipan,” Karathanasis said. They found that annual ryegrass extracts were unique among all test solutions, the only one to affect the integrity of fragipan. It led Murdock and his team to suggest that annual ryegrass roots exude chemicals that loosen the molecular bond in fragipan soil, which ryegrass roots then penetrate and pry away.

And when Murdock added a humic product to his greenhouse tests, the annual ryegrass appeared to have had an even greater impact on fragipan degradation.

Although Olk had met Murdock at the No Till conference in 2016, he had not become much more familiar with the cover crop project, nor the people Murdock worked with, including Junior Upton, Mike Plumer and John Pike, a research agronomist with the University of Illinois. Then in 2021, the USDA lab where Olk works hired Dr. Claire Phillips, who had academic roots in Oregon and who knew about the cover crop work being done on Junior’s farm. In fact, she had met Mike Plumer on his Oregon trips, where he reported on the cover crop project, including Murdock’s research. Phillips made the introductions and the deeper connection to the USDA research team began.

Olk’s research will delve ever deeper into the mystery. In the  5-year project plan written to support the research, Olk said: “Two proposed mechanisms (to demonstrate how fragipan is weakened through annual ryegrass cropping) are that (1) ryegrass growth creates a solution with a high sodium saturation ratio, which disperses fragipan particles; and (2) ryegrass root exudates contain chelating agents, which bind to aluminum and iron molecules in the fragipan, thus helping to disintegrate those cementing agents within the fragipan.”

Another characteristic of fragipan is that it causes overly wet surface conditions early in the growing season, due to poor natural drainage. Later in the season, crops dry up because the shallow water supply evaporates or is absorbed quickly by the crop.

The USDA research will address that issue as well, relying on further field work in a number of Midwest locations, including Junior’s farm in Illinois. Additional lab and greenhouse research will continue in Kentucky, as well as at the USDA labs in Iowa.

Here are more specifics as to the scope of Olk’s research, related specifically to annual ryegrass:

  1. “We will look more closely at the impacts of long-term artificial drainage on soil health.”
  2. “We will study the seasonal soil hydrology of corn-soybean rotations with and without annual ryegrass winter cover crops. We will test the hypotheses that (1) ryegrass growth removes excess soil moisture in springtime, and (2)  it degrades the fragipan sufficiently as to deepen the cash crop plant rooting zone, thereby increasing plant-available soil water later in the growing season.”
  3. “We will determine the chemical composition of fragipans at varying stages of degradation by annual ryegrass and humic product application”
  4. “We will determine the effects of a humic product on root exudates released by annual ryegrass in a hydroponic (lab) system.”

After his research, Murdock said the use of annual ryegrass, as a cover crop, could dramatically change the output of crops on fragipan soils internationally. Olk’s research will evaluate that claim. If proven true, annual ryegrass could become an inexpensive method to add profit to formerly marginal acreage. It would also help to lift a burden that has restricted agriculture on fragipan soils for centuries.

Annual Ryegrass – the Germ Seed of Cover Crop Adoption in the US – Part 19.

Mentorship and Inventiveness

Marc Bremer, 38, is a fourth-generation family farmer from Metropolis, Illinois, whose story unifies two things that characterize the growth of cover crops in the modern era. The first is the importance of mentorship. The second is the role of “ah ha” moments in our lives, which continue to fuel enthusiasm for progress and productivity in agriculture.

In Marc’s case, as with others in this 25th anniversary tribute to annual ryegrass as a cover crop, Mike Plumer’s influence as a teacher has been crucial. And, as for those “ah-ha” moments, you’ve probably come to understand that they occur in every life and every generation, often at the crossroads of challenge and opportunity.

Marc Bremer’s grandfather started a farm and cattle breeding business with his brother after WW II, on what grew to 600 acres. His contribution to the industry included the advancement of cattle breeding practices. Likewise, Marc’s father (David) and grandfather were early adopters of no-till, working with the nearby Illinois Extension at Dixon Springs. Marc’s contributions include the widespread use of cover crops, annual ryegrass in particular, and how it has compounded the farm’s success.

Bremer Brothers Farm seems wedded to the adage, “Work smarter, not harder.” Marc’s great grandfather did that by doing his homework, becoming an avid record keeper, and using that data to drive decisions. “After purchasing their first Angus livestock in the 1950s,” Marc said, “we haven’t bought another female since. My dad was working on a master’s degree in genetics from the University of New Mexico when granddad passed away, prompting dad to come back to the farming operation.” His academic work clearly complemented that which the preceding generations had put to work. The science of breeding, combined with their nutrient-rich, efficient feeding system, has made their herd one of consistent quality and value, decade after decade.

No photo description available.

Marc’s grandfather decided in the mid-1960s that no-till would benefit the soil and keep it in place. “With support from Dixon Springs Extension researchers, grandad started using the no-till planting system to great effect,” Marc continued, “and purchased a 6-row Allis Chalmers, which was among the first commercially-available no-till planters. My dad followed suit, continuing to graze crop stubble on our corn and bean acres after harvest.  He also started experimenting with cover crops in the 90s, then introduced grazing onto those acres.”

Mike Plumer was a friend of the Extension Agent working in that part of Illinois during those years and became friends with the Bremer’s. That friendship extended to the next generation when, in the early 2000s, Mike visited Marc in Wyoming to hunt antelope on the ranch where Marc worked as a ranch hand and mechanic. In order to be closer to family and move into leadership on Bremer Brothers Farm, Marc moved back to Metropolis in 2010.

By then, Mike had left the university and started a consulting business. By then, he had learned about annual ryegrass and had helped others in southern Illinois add cover crops to their operations. By then, he had partnered with the Oregon Ryegrass Commission and was overseeing research trials in multiple Midwest locations. Mike became more active as an educator as well, advising famers about annual ryegrass at national ag shows and field day demonstrations.

Marc embraced cover crops quickly and, like his father before him, invested in equipment “to expand the farm without more land. We just learned to do better with the 900 acres we had,” he said. After a couple of years using a 15’ Great Plains drill, he purchased a 40’ drill that is pulled behind their 320 hp Cat Challenger on tracks.  From the early days, towing a 6-row planter, the Bremer’s have now graduated to a 24-row Kenzi planter.

“It may have been as late as 2011 that Mike convinced me to use annual ryegrass because, by then, he understood that it broke up fragipan soil which is prevalent in this part of the country,” Marc said.

“I didn’t introduce annual ryegrass to the whole farm right away,” he added. “But during the 2012 drought, we saw such a dramatic difference between acres planted in annual ryegrass, versus plain no-till or with cereal rye, that we were convinced.”

The Bremer’s experimented too with whether livestock and grazing the cover crop would affect the growth of annual ryegrass roots. “We brought out a 4’ soil probe and it looked like grazing didn’t impact root growth at all. Compared to neighboring property with no cover crops, it appears that annual ryegrass gradually gets rid of fragipan, does a better job of suppressing weeds and, by having cattle grazing the pastures, there are fewer slugs and voles to contend with.”

In a recent study concluded by the University of Kentucky (Lloyd Murdock), Bremer’s farm was shown to have gained more than 6 inches of new soil in seven years, simply by having annual ryegrass as a cover crop, slowly reclaiming the layer occupied by the otherwise impenetrable fragipan. In the same period, the amount of organic matter increased from 2.0 to 3.5 percent.

Another recent “ah ha” for Marc was that when he terminated the cover crop early in the spring, as he’d been strongly advised to, the fields would remain wet and prolong the planting date of corn or beans. He thought if he let the cover crops grow later, it would allow earlier planting. “I’ve experimented with planting corn into cereal rye as tall as 7’ and annual ryegrass as high as 4 ½ feet. Then I’ll come back and terminate the cover crop, and for the most part it still kills nicely,” he said. “I figure that even if there is some residual seed from the cover crop, it will lay dormant under the corn until fall or can be controlled with a post application of herbicide, which is fine too.”

Bremer Brothers Farm is part of the new round of research mentioned in the last chapter, headed by USDA/Ag Research Service in Iowa. The research at Bremer’s has two aspects: first, how the chemicals exuded by annual ryegrass roots degrade fragipan, and secondly, studying the how grazing cattle on cover crop acreage affects soil hydrology. “This research has widespread value for agriculture,” Marc said, “to better understand nutrient cycling, and how soil holds moisture.”

Marc and his wife have three children, a daughter and two sons. One of the gifts Marc is preparing for them, should they opt to take the farm into the next generation, is that the land is now producing value 11 months of the year, rather than the five or six months of many neighbors. “With cover crops and grazing cattle, the land is more productive, and the soil is healthier,” he said. “Livestock and cash crops work so well together. Annual ryegrass as a cover crop enriches the soil, gets rid of compaction, and improves the water carrying capacity of the soil. Cattle break down crop residue, provide nutrient-rich manure and get rid of voles and slugs. Voles and slugs, as it turns out, can’t bench-press a cow,” he added with a laugh.

“When I arrived from Wyoming in 2010, we had 90 cow/calf pairs and 210 in inventory. To support that herd, we were feeding them 100 tons of hay a year. Today, we have about 110 cow/calf pairs and 275 in inventory. But we’re feeding them less than 90 tons of hay. The difference is that they’re getting fed by grazing cover crops. We’re more profitable, the soil is healthier, and our corn and bean yields are higher. Like my dad and granddad said, ‘You don’t necessarily have to buy more land to expand your business.’”

Annual Ryegrass – the Germ Seed of Cover Crop Adoption in the US – Part 17

 Filling Some Legacy Shoes in Cover Crop Research


As a youngster, John Pike watched Mike Plumer excavate a small pit in a cornfield not far from his own family farm in southern Illinois. Plumer, at the time, was an Extension agent at the University of Illinois.  “He was there to demonstrate how the fragipan soil common to southern Illinois prevents healthy root growth and negatively impacts crop yields,” John said. “The pit clearly showed corn roots hitting the fragipan but not penetrating it.”

At the time, Plumer hadn’t discovered how annual ryegrass, used as a cover crop, gradually breaks down fragipan and allows deeper root growth. “But even then, before he made that connection, his curiosity and deep conviction in conservation tillage made a big impression on me,” John added.

That field day demonstration stuck with John as he later attended college and followed in Plumer’s footsteps at the U of Illinois, becoming an Extension agent and later a research agronomist for the Department of Crop Sciences, in charge of research station operations in the southern part of the state. “It was such a pleasure to have the opportunity to know Mike as a friend and to work with him professionally, before and after his retirement,” he said.

John’s career with the university focused on soil fertility, nutrient management, and water quality. Cover crop research became a significant part of that work. When the university shut down four of its research stations, John started his own ag consultancy as a research agronomist. And that, he said, led to “a more flexible and comprehensive range of work,” a lot of which involves working closely with researchers from other universities.

“Universities have historically been a major source of innovation for the ag industry,” John continued. “But with cover crop discoveries, it was largely the reverse, with innovation coming from the field and gradually informing the universities to backfill with research that quantified the benefits.”

He went on to explain why. “Research involving cover crops is not always best suited to the small plot design used on most university farms. Further, as it relates to cover crop research specifically, the typical 3-year funding cycle common to many research programs is not long enough to capture the cumulative impacts of a cover crop system.  The use of annual ryegrass as a cover crop in fragipan soils is an example. While short-term benefits become evident quickly, like erosion control and nitrogen recycling, the impacts of ryegrass on fragipan soils are realized only over a longer timeframe; the effect of annual ryegrass on fragipan becomes pronounced between the third and fifth years, when corn crops show significant gains in rooting depth and yield.  So, funding a 3-year research program might discount the true potential and lose out on some of the most remarkable impacts.” 

Given that the cover crop revolution didn’t start on university farms, it’s more understandable why some professors and Extension researchers were reluctant to sign on as early cover crop advocates. In fact, some actively campaigned against annual ryegrass because they feared the cover crop would create more headaches than benefits.   

The reticence of university researchers, however, did not deter farmers like Junior Upton (Springerton, Illinois) and independent thinkers like Mike Plumer. Their on-farm discoveries of annual ryegrass’ benefits in the mid-1990s won early support from Oregon ryegrass seed growers as well as their Ryegrass Commission. A decade of replicated field trials helped determine which annual ryegrass varieties were the most winter hardy and which management practices were most effective for control of cover crops with herbicides. The trials also attracted media attention and thus increased university interest.

“Farmers change their crop management practices only when the economic benefits can be demonstrated,” said John, who has continued to farm his own acres as well. “Telling them about soil health is secondary to economics. So, when they hear from their neighbor or find out for themselves that cover crops can save you money or boost your profits, they pay attention. Annual ryegrass does that by reducing erosion and compaction, while boosting yields, improving water infiltration, and many other things.”

So as Mike Plumer retired, and passed away shortly thereafter, John has tried to continue some of Mike’s projects and maintain relationships with many of his long-time farmer/collaborators.  “I like to think I’m helping to keep the ball rolling,” he explained, “but it’ll take many more people like me to move the ball as far down the field as Mike did.  I’m just glad to make sure his efforts and interests are continued, as we shared the same interests.”

The Ryegrass Commission has hired John to further Plumer’s work, with Junior Upton and many of the other growers Plumer attracted to cover crop usage. One of those happy customers, Illinois farmer Marc Bremer,  has been using annual ryegrass in rotation between cash crops and grazing cattle for 15 years. On grazed pastures, he’s seen corn yields increase to 230 bushels/acre and beans to 80 bu/ac. John’s research will create data on the further reduction of fragipan on that farm over the next five years, comparing grazed and un-grazed fields using annual ryegrass to other acreage tilled in the old “conventional” way without cover crops.  

In addition, John will be following up with the University of Kentucky, as researcher Lloyd Murdoch heads into retirement. John will further Murdoch’s work and provide crucial location assistance to Dr. Claire Phillips, a scientist working with USDA’s Agricultural Research Service in Ames, Iowa. “I’ll be monitoring their test sites in southern Illinois,” John said, “including acreage owned by Junior Upton.” “We’re placing field sensors to track hydrology in soils affected by fragipan and gathering data on soils freed from compaction by using annual ryegrass,” he explained.

“Water management is critical in our region and, really, in most parts of the world as well.  Reducing runoff, soil erosion and related nutrient loss is a major factor in the efficiency of our mostly unirrigated row-cropping systems,” John added. “Employing annual ryegrass as a component of cover crop programs helps to keep soil in place, improve water infiltration rates and significantly increases the rooting depth limited by fragipan soils.  “This USDA-ARS led research has national implications,” he said, “and will help to further quantify the impact of annual ryegrass on fragipan soils and its relationship to the soil’s ability to hold more available moisture.” 

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.”

The Germ Seed of Cover Cropping in the US – Part 13

Annual Ryegrass…When “Breaking Up is Hard to Do”

An “aha” moment began this 14-part series, and it’s fitting we end it with another aha moment!

Dr. Lloyd Murdock has spent many of his productive years at the University of Kentucky as a soils and crop specialist. The link in the previous sentence summarizes a decades long effort that has earned Lloyd a well-deserved reputation as one of America’s “pioneers of no-till agriculture.”

“I had retired in 2012,” Lloyd recalled, “but specifically returned part time the following year to focus research on how to eliminate, or at least reduce, a deep layer of cemented soil called fragipan. Of course, during his career, Lloyd was aware of the seemingly intractable fragipan problem. “But with all the other things I was involved with, I didn’t have enough time. So, when I returned in 2013, I involved a soil chemist, soil pedologist and another agronomist and we set about doing lab, greenhouse and field testing on how to break up that cemented layer.” The breakthrough project is described in a lengthy report published last year by the University of Kentucky.

Fragipan soils are present in almost a third of the US, running from east Texas northeast into New York and parts of New England. In Kentucky alone, it hampers agriculture on 2.7 million acres. Fragipan is almost like bedrock in places, beginning anywhere from 18 to 32 inches below the soil surface. The layer becomes cement-like because of an iron-associated aluminosilicate that binds soil together tightly and restricts water penetration and root growth. Crops grown on these soils have limited soil depth, below which crop roots cannot go. Furthermore, in wet weather, fragipan prevents proper drainage. Topsoil gets saturated and squeezes out oxygen, increases the loss of nitrogen, delays planting, and increases the chances of even more soil compaction with any new tractor traffic.

In the 40 years he was researching and teaching the benefits of no-till, Lloyd said he recalled how people were addressing fragipan. “I was involved in early experiments injecting lime or other chemicals into the pan on 30-inch centers, hoping to break it down,” he said. “I was aware of field trials at other universities using deep mechanical rippers to break up the fragipan.  But in a short time, the soil would reconfigure and harden once again. It was quite expensive and none of it proved effective.”

Then in 2014, through the Oregon Ryegrass Commission, Lloyd was introduced to Mike Plumer, another pioneer in conservation agriculture who had been working on contract to the Commission since the early 2000s. It was he who had begun to quantify the value of annual ryegrass as a cover crop. Inadvertently, at Ralph “Junior” Upton’s farm in southern Illinois, they stumbled on the discovery of annual ryegrass’ deep roots. And in the process, they saw how ryegrass roots seemed to be growing into the fragipan on Junior’s compacted acreage.

“Everything happened by accident,” Junior said. “When I started, I only had about 5 inches of topsoil before I would hit the fragipan. I was trying to get through dry weather. I got a grant and started studying no-till and cover crops. Then a representative of Oregon Ryegrass Commission asked me to try annual ryegrass as a cover crop.”

“They’d stumbled onto something really big,” Lloyd said. “Thankfully, Mike and Junior kept good records on their annual ryegrass work. They found that after a few years, the corn production on the acres Junior planted annual ryegrass began to outproduce fields without it. When they started tracking progress on those fields in the early 2000s, he and Mike determined that Junior’s acreage was producing 10 to 20 bushels per acre less than the average in that county. Today, those same acres are producing 40 bushels per acre more than the county average.