Keyline plowing results: 522,720 worms for $280

Categories: On The Farm

How something is tested is just as important as the results. Part of the scientific method is just figuring out if you asked the right questions and tested appropriately. So here we more fully describe what we did, existing conditions, and the farmers’ management. 

In a follow-up to our first article on keyline plowing, here are details of the trial conducted in Vermont

After hearing about keyline plowing from advocates in Vermont, farmers wanted to know more. They wanted to know if it truly could reduce compaction, build soil and increase carbon sequestration. Four Vermont dairy farmers offered their farms as sites to test the plowing system, and we began a three-year research project, working with Mark Krawczyk of Keyline Vermont, a trained keyline expert.

Our intent was to use the tool as prescribed and then to gather data to tell us what kind of changes could be expected from the practice. To make sure that the data we collected would be useful, we wanted a variety of pastures and similar untreated pastures for comparison. The pastures chosen for treatment were selected by the farmers because they were in need of improvement. The farmers had plans to completely rehabilitate those pastures but were interested in trying keyline plowing as an alternative.

The keyline-plowed pasture is ready for sampling.

Mark Krawczyk of Keyline Vermont owns a Yeoman’s plow and knows how to keyline plow. He came out and found the keypoint for each paddock, plotting the keyline with temporary flags. Hitching his 3-shank plow to the farmer’s tractor, he plowed the paddock to about 10-14” depth for the first pass at the beginning of the grazing season. Later that summer, he plowed a few inches deeper. The third and fourth passes were completed in the second year. By the fourth plowing, the shanks were at their fullest extension, reaching depths of 20” or more.

We collected soil samples from the plowed and unplowed paddocks. This is a composite sample, where we mixed up smaller samples from different spots around the paddock. The samples were analyzed to see if there were benefits to keyline plowing.

Before and throughout the process, the dairy farmers maintained their grazing management. For three of the four farmers, herds of dairy cows or heifers grazed for 12 to 24 hours on the pasture, and farmers were careful to avoid overgrazing. The fourth farmer used longer grazing periods, and often used both control and plowed pasture space to support his heifers. [Note: this is a correction from the previous statement of 4 farmers all using similar management.] The herds were brought into the paddocks when forages were at about 8-12” and came off before the forage reached 3-4”.

A team of us from the University of Vermont, including soil scientist Josef Gorres, myself and graduate student Bridgett Hilshey, collected soil and forage samples from the keyline plowed pastures and from the neighboring comparison pastures before during and after the two years of the project. For good measure, we also tested penetrometer resistance and rated the pastures’ conditions. For each soil sample, we did a basic soil test, and measured organic matter content, soil strength, bulk density, linear porosity and active carbon.

One of the key things that farmers were interested in improving with this treatment was compaction. All four farmers felt their pastures were lagging in productivity and quality, primarily because of compaction, and while they were still functional, the farmers wanted to rejuvenate them.

An example of compaction by hoof and tire. Courtesy of NSW Australia’s Department of Primary Industries 

Soils can get compacted from machinery traffic and from animal traffic. The hooves of animals can force a lot of pressure on those upper 4-6 inches of soil. If animals are out grazing when the soil is wet, compaction is even more likely. Some studies have found pasture yields can be 16-40% lower as a result of compaction. Keyline plowing was ideal because it was said to alleviate compaction, increase pasture yields, and it wouldn’t interfere with grazing management. Since the plowing doesn’t disturb the pasture measurably, the herd could go back to grazing soon after each plowing event 

Good soil is on the left and compacted soil is on the right.  Remember that soil is usually half solid and half pore space. The pores, especially the large ones, are important to hold water and for soil organism habitat. Compacted soils end up holding less water, with less capacity to cycle nutrients. They end up being less productive.  Thanks to NSW Department of Primary Industries for this illustration. 

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