Tag Archives: mitigating fragipan

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.