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.