Editor’s Note: Comments on our first article, suggested that there were no claims of 8 inches of topsoil increase per year. It is true that most proponents cite increases of 12 – 18 inches over 3 years. Here are sources we drew from:
“We’ve seen it happen in a single year of 8 inches of conversion from this mineral to this darker, aerobic, root-filled topsoil.” from Sweetsoil quoting Abe Collins, Carbon Farmers of America
“During an average three-year conversion phase, four to six inches of new topsoil are typically formed each year.” from “Keyline Design Mark IV – Soil, Water & Carbon for Every Farm” by Abe Collins and Darren J. Doherty
“It is through this two part process, repeated over the course of three years, that Yeomans has observed and reported the development of 12-18 inches of healthy, living topsoil.” from Ecosystems Design Inc.
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.
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.
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.
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
Even though originally, we were trying to address soil compaction, active carbon was the key characteristic for us to watch. It responds quickly to management changes, because active carbon is tied to changes in biological activity, meaning that if there is much more food available for soil microbes, there would be more active carbon present. If changes were afoot, we should see it in active carbon measurements.
Out of the hundreds of samples, and readings, and measurements, we saw no changes. No changes to the very responsive indicator, active carbon, and no changes in other soil or forage characteristics, such as soil organic matter or bulk density, or forage NDF. What this trial told us is: keyline plowing didn’t change soil or forage quality on these four farms over the 2 ½ years we were monitoring pastures. There may be additional conclusions to draw, but first let’s talk with the farmers.
The farmers told us some more. They were pretty frustrated by what keyline plowing did- three of the four said it made those paddocks very bumpy to walk across. For the ones that hayed or mowed pastures in addition to grazing them, they said that the tractor ride was very uncomfortable. The shanks of the plow pulled up stones, and that was really irritating. Mark added a roller behind the plow to smooth the surface, but the slices still made the pastures a pain in the tush.
A couple of the farmers were dealing with moisture issues in their pastures. In one case, the farmer noted that it seemed like the plow lines were moving water away from wet spots, and that was appreciated. In another case, though, the farmer said it seemed like the plowing dried the pasture out more rapidly, and the plants looked like they were drought stressed.
There was another group we still wanted to hear from. Earthworms are pretty good indicators of soil quality, and we were counting on them to shed more light on the situation.
There are three main types of worms: Endogeic, epigeic, and anecic. The endogeic and the epigeic stay closer to the surface. The anecic, though, burrow deep into the ground. Those deep burrows can translate into lost nutrients, when the materials the anecic worms have transported are washed deep into the soil profile, sometimes reaching the groundwater. The worm counts told a story that we didn’t find anywhere else. We found higher numbers of endogeic and epigeic worms in the keyline plowed pastures than in the control. The numbers of anecic worms were not that different though.
There was an average of 27 endogeic and epigeic worms per square foot in the keyline plowed pastures, versus the 15 per square foot in the control. An acre has 43,560 square feet. With an extra 12 worms per square foot, there were 522,720 more worms per acre in the keyline-plowed pastures. The presence of more worms suggests faster turnover of nutrients and better aeration.
The cost of keyline plowing was about $280/acre, or about 1867 worms for every dollar. Since we didn’t find any increase in forage, forage quality or other soil quality indicators, we’re left wondering if opening up the soil to more worms is worth it. More worms has usually been considered a good thing, and at almost 20 worms for a penny, those worms seem like a great price.
It turns out that worms might not be the best things for climate change, though. The process of churning and digesting organic matter seems to increase the release of greenhouse gases and doesn’t seem to increase the amount of carbon being stored in the soil.
With the verdict on worms not 100% positive (sorry, worms, we really do love you!), we’re still asking, what will we see in the long run? We haven’t seen the 8” of topsoil that was touted, with no increase in organic matter or active carbon. Since we burned a good bit of diesel for those worms, we definitely didn’t do the environment any favors.
Is it that keyline plowing is more suited for drier climates, where water is a limiting factor in production? We’re still working on that answer, and we’ll get back to you. Keyline plowing has been out there for decades, though, so if you have any evidence or data, please share it!
Until then, it’s hot out. Let’s dig up some worms and go fishing.
Interesting … I was going through the Internet rabbitholes looking for permaculture ideas and ran into this.
It’s logical that a trashed, compacted pasture would benefit more than a good pasture because it has more room for improvement – in the same way that in any process the improvements come harder and harder as you find and fix the bigger problems.
I am extremely dubious of claims like this. – “In 2008 we saw 9” deep topsoil profiles become 17” + in a single growing season.”
It sounds way cool, but how is Yeomans defining “topsoil profile” ? By plowability, by physical or chemical characteristics? By appearance? In the arid Southwest, doubling your topsoil usually means someone uphill has an erosion problem and his topsoil landed in your fields.
Driving up through Arizona, Utah, Idaho and Montana we saw quite a few applications of “keyline” concept (never knew it had a formal name). Usually it was a farmer with a wheat or alfalfa field in the sweet spot where the water was most abundant, and cows grazing the steeper slopes above it. Occasionally it would be an orchard.
Although long belated, I’m finally getting around to sharing thoughts on these 2 keyline-related articles. I’m the keyline plow practitioner contracted in this study by the University of Vermont. I’ve been doing part-time contract subsoil plow work for clients in the northeastern United States since 2008 (note – I do not sell Yeomans plows). As a student of keyline design since 1999, I’ve since been fascinated by PA Yeomans’ dynamic and whole-systems approach to land planning. Although the term ‘keyline’ describes Yeomans specialized subsoil plow design (notable for the thin profile of the shanks and the low angle at the boot of the shank – both of which reduce necessary horsepower and surface disturbance), it also describes a physical plane in the landscape (the ‘keyline’), as well as a whole farm planning tool that aims to develop soil and water resources while responding directly to the landscape’s topography. While this is a bit of an aside, I feel it’s worth once again pointing out that ‘keyline plowing’ is just one component part of ‘the keyline plan’ as a whole.
In my five years doing contract subsoil plow work, I’ve had the pleasure of working with roughly 30 farmer-clients. I’ve been neglectful in keeping tabs on any results that they’ve seen in response to my work, and it’s been very difficult for me to assess changes between seasons and years, as I do not know their farms intimately nor do I generally have the time to do any real monitoring. Because of this I do not have much to add to the conversation in regards to quantitative changes in soil parameters and forage production.
That said, I’ve only ever suggested prospective clients consider subsoil plowing if compaction appears to be a limiting factor or they’re looking to address soil moisture issues. To my mind, it’s these two instances that make subsoiling an worthwhile investment. Like Owen Hablutzel, I’ve understood keyline plowing to be one part of an integrated suite of practices used to rehabilitate soil – including management intensive or holistic high density grazing, soil biological inoculants, addressing soil nutrient imbalances, etc. Keyline plowing is certainly not a magic bullet, and though I may be mistaken, I believe that the quotes included in the second article’s editor’s note that include claims of soil formation in response to keyline do not solely refer to soil responses to keyline plowing, but a change in grazing management as well (although it’s unclear from the source excerpts). For a revelatory insight into the origins of keyline in Australia, check out this vintage 15 minute film produced by the Royal Bank of New South Wales in 1955 (http://player
that examines PA Yeomans’ work. It’s remarkably well-produced and offers an insight into the soil conditions Yeomans was working with.
I value the effort and energy invested in this study, and I most certainly agree that we need qualitative analysis as to the effects of keyline plowing (especially when coupled with other complementary soil-building and management strategies). I would of course have liked to have seen much better results, and while I’d prefer to avoid coming across as defensive, I must share that I did have several doubts, or at the very least, concerns about a number of aspects of the study and frankly, was surprised to see the results of the trials published. My primary concerns are as follows –
1 – While I understand that the researchers state that participating farmers did select paddocks that they felt were lacking in productivity, I was unaware of pre-trial soil conditions and in the case of at least one (of 4) participating farms, I would be very surprised if soil compaction was truly a limiting factor. Again, as a professional, I would not suggest keyline plowing to a prospective client if their soils do not already suffer some type of compaction or waterlogging within the top 18″ of the soil profile.
2 – Although I realize that the article text has been partially amended to reflect this, I’d like to again point out that at least one participating farmer did not follow research protocols by managing cows using the baseline 12-24 hour rotation. Additionally, and I do not believe included in the articles, another participating farmer told me that he ‘believed’ that the subsoiling had made a difference in his test paddock, and had even gone on to use it as a sacrificial paddock when other portions of the farm were too wet to graze, knowing that I’d be back to rip in another few months. While valuable as qualitative feedback, this left me feeling quite concerned as to the reliability of any ensuing results. I did mention these concerns to the researchers.
3 – As regards cost, just to make sure we’re clear, $280/acre is the result of 4 subsoil plow treatments over a 2 year period with $120 of that total budgeted towards tractor use ($30/acre x 4 treatments) and $40/acre covering my costs for plow rental and operation. This figure is significantly less (roughly $20 per acre per pass) if farmers rent the tool (although they of course still must spend their own time plowing) or if they were to own or share the implement.
4 – I was under the impression that the study would unfortunately not be ‘publishable’ in academic journals due to an insufficient number of test plots at each site. My understanding was that an insufficient number of soil samples at each site and high variability between samples brought about results with low statistical reliability. Although the study results did indicate keyline plowing had no effect on soils (save for those lovely (but hungry) earthworms), it was not possible to determine if it was the result of the tool or under-sampling.
More than anything, the take home for me is that we need more sampling and monitoring to gain a clear understanding if and how keyline subsoiling plowing affects pasture productivity, soil parameters, and animal performance. I’ve also learned how truly challenging it is to design and manage an experiment on a working farm while maintaining real controls. My intention here is not to undermine the work of any of the members of the research team, but rather create space to share my perspective. I sincerely appreciate the work that they do to provide land managers with sound science to inform their decision making processes.
To that end, I’ll also point folks to the work of Peter Donovan and the Soil Carbon Coalition. This organization is sponsoring the Soil Carbon Challenge whereby they offer participants the tools required to carry out their own replicable soil monitoring, – soilcarboncoalition.org/files/MeasuringSoilCarbonChange.pdf
Peter distinguishes this ‘monitoring’ work from ‘research’ in that it aims to discover the edges of creative possibility as opposed to research that isolates a few individual practices. I am by no means a research scientist, but I do value the insights I’ve gained from published research. The Soil Carbon Coalition creates a forum for individuals to share the results of their own monitoring efforts on a navigable on-line map. This seems to be an ideal location to begin building a more varied and diverse set of data on soil rehabilitation practices. You can view the map here – http://soilcarboncoalition.org/changemap.htm
Whatever the case, I hope that this trial only marks the beginning of more varied keyline research in diverse climates the world over.
Thanks for the work Rachel – More questions (of course)…
Is Vermont pasture moisture limited for summer forage production? It looks like you get around 3″ a month all summer. How was rainfall in the years of the study?
You mention the risk of compaction. How would you describe the condition of the four fields you studied relative to the range of conditions you find in VT pasture? Do you have a quantitative basis for comparison of your sites to ‘typical’ conditions?
You didn’t provide any info on means or variability, or discuss any pattern in variation. Did you use any statistical methods? In ecological research, with a n=4, there is always the opportunity that finding “nothing” is just a result of study design.
Did you write up your findings in a more technical manner somewhere? I appreciate the colloquial report, but would be greatful for more detail. As you know, keyline plowing is essentially a variation on contour plowing, which is a well tested practice for soil conservation in places other than VT. Regardless of VT marketing claims, keyline plowing was originally designed to support spreading of high rate flood flow irrigation from on-farm storage–the plowing pattern is integral to the site design process, and was designed for areas with irregular rainfall and summer drought. Some readers might not be able to put your study in context, and might walk away thinking that contour sub-soiling is useless in general (rather than being situationally useful like most BMPs). For example, in my region, loss of rainfall storage in the canopy and soils in rural environments is responsible for the decline of freshwater aquatic ecosystems (PNW; as in Booth et al 2002). I am curious what on-farm measures (like winter runof interception, storage, and infiltration techniques), could restore hydrologic function and have a benefit for both farm and public trust resources, and would be grateful for a little more take-away info.
Thanks for your questions. I’ll try to answer them in the order you asked.
Pasture moisture is not always limited in Vermont, but some years have long dry periods or long wet periods. As always, organic matter provides increased infiltration and water storage. In 2011, there was both a long drought and a devestatingly huge flood due to Tropical Storm Irene. NOAA would have the best reports on weather history that you may be able to access easily, don’t you think? [Note to any other readers that Paul’s email marks him as NOAA affiliated.}
I don’t want to give an inaccurate impression of the pastures in this project or of those in Vermont in general, but I’d say that these were relatively typical. There was evidence of compaction, as measured via penetrometer, and those measurements seemed similar to what I’d expect in many pastures. Note: penetrometer resistance varies by soil type, management, and moisture content.
In this type of a publication, we don’t intend to publish the same way we would in a peer-reviewed scientific journal. Statistical analyses were done to determine the absence of a response for the variables measured. I don’t have P values to provide at this time.
We are working on a more technical report of this information, which we can make available as it is published. A scientific publication was not an intended outcome of the funded project, but we would like to share as much as possible to add to the body of information out there. We are making slow headway with this, as the members of the project team are incredibly busy with other projects; for example, I am aslso working (for free) as co-editor of an online grazing magazine.
Given your reference to rainfall storage, we can again point out that we were merely looking at the practice of keyline plowing, which had been explained to build very large amounts of organic matter. It is similar, but not the same as subsoiling, in that it relies on the key line and it is meant to be done with a less disruptive tool, the Yeoman’s plow. Keyline plowing fits into the larger picture of Keyline design, which utilizes groundscaping, similar to the work done by ancient communities such as the Nabateans.
Thank you for your interest and your support.
Thanks for filling in more, Rachel, this helps to understand things better.
It seems pretty odd to me that earthworm activity didn’t impact other metrics. Shouldn’t increased earthworm activity have an effect on active carbon as well as soil bulk density and penetration resistance, as well as the rate at which manure nutrients cycle?
Is it possible that there is some other change that is negating the effects that we should see from the worms?
Is it possible that positive impacts from worm activity will take a while to accumulate? Are you going to continue following up, or is the project out of $? Of course, the worm spike could be temporary.
Glad that this helped. Thank you for getting back in touch.
As with much of research, often we are left with more questions than we had when we started. This project was limited by funding and resources, which does not allow us to answer all the questions that we still have. Given the presence of statistically greater numbers of earthworms where the pastures were plowed, we would expect to see effects on soil quality. We can’t point to a simple reason why we weren’t able to capture any differences in soil quality, but here are a few possibilities:
-soil quality was not poor enough to register the changes.
-variability in soil quality across the pastures rendered differences statistically insignificant.
-there has not been enough time to measure the impacts of the worms.
We are hoping to take measurements down the line, but we are not sure that the farmers will continue to maintain their pastures at the status quo; in the intervening time, some farmers may plow up pastures entirely, while others may seed down portions.
Meanwhile, this is as good a time as any to reiterate that this was only done on 4 farms, it’s only meant to be a portion of the answer, and it was done where water is not a limiting factor. Additionally, the farmers were and are good managers and stewards of their land, but there were some anomalies that occurred over the process. One of the farmers did not utilize rotational grazing on the 12-24 hour cycle consistently in the control and test areas, and that discrepancy is amended in the text of the article.
Very interisting results on paper and is what is susposed to be there. But go to the bottom line was there more milk there. Did it make any money. That is the gauge you should be using
This is all very interesting as have quite a few of our alumni and clients on our Facebook (www.facebook.com/heenandoherty) pages who, like myself, have found outcomes to be much different to those found in Vermont in this trial.
Just this weekend I was at our farm where I’ve done three passes (with 2 year spacings) of our 19 year old 3 shank Keyline Plow and was amazed at the impact its use has had on the heavy clay B horizon which we’ve now only just started to cultivate (in April 2012) after going 6″, then 8-10″ then 12-14″ on the last pass finally getting into this non-reactive ‘potters’ clay.
As I posted on Facebook ,
“(Our) Soils that when we started had 50-100mm root depths, below which was well structured, but lifeless clay loam, then a 50-100mm thick buckshot layer that went to soup when wet and cement when dry (a pan in other words) and then below that is this (pictured) orange/yellow or yellow/red heavy clay that is part of what makes Bendigo quite famous: for its excellent pottery! We are now getting into this heavy clay with our life-intrusion and when we crack through that 40-60cm layer we’ll be in the C horizon and its weathered mud and sandstones…”
Picture referred to:
I can only stand by the outcomes that we’ve experienced ourselves and on our client’s farms which are by and large the opposite to this. We also feel that the rather ‘tabloid-esque’ headline talking $/worm is pretty misleading when this was a research trial and not reflective of a more likely program where in most cases people would not spend anywhere near that much as they’d usually own their own plow and the costs would therefore be much less. Our clients and alumni have also questioned this figure as being not reflective of their reality. We enjoy reading ‘On Pasture’ and I don’t think that there is the place for this kind of headlining in order for you to grab attention…
Nonetheless, like the Marin Carbon trial in California, the results from this trial are pretty much to say that Keyline Plowing is a waste of diesel and time when it comes to soil building. I find it hard to argue with these outcomes in both of these cases as they evidently followed the process that one is supposed to. I and others have had different outcomes, but we’ve not followed research protocols so who bloody well knows what is happening to have outcomes that are so different. Maybe as one of our correspondants suggested, that these soils were already in pretty good shape. I also agree with the point that Geoff Lawton apparently put forward, in fact Research Mycologists I’ve spoken to say that ANY culivation of any type will initially impact fungi.
I’m very happy to stand behind any ‘claims’ that I’ve made in any articles or courses or consultancies, as they are based on what have been physically achieved on a wide variety of sites over, in my case at least now 20 years. However its important to determine the use of any tool by having its application tested within a Holistic decision-making process. In the case of many of our clients and alumni this has been to use the plow as a remedial tool as the site demands the use of implements such as this to overcome significant issues.
Thanks and all the best,
We are glad that you joined this discussion, and we appreciate your reflections on the topic. The image you posted in your comment seems to show an earthworm channel filled in with organic-rich soil. What a great visual.
Putting a price on a worm does seem like an odd way to go about it, but you agree that farming has to be financially viable to be sustainable. When we cited the cost of keyline plowing, we calculated the equipment as a rental cost. In the northeastern US, many farms are only 200 or so acres, which might not necessarily justify the cost of a $7-10,000 plow.
If the farmer elected to purchase the plow at the lower price, and was able to plow 200 acres, the cost would be $35/acre for equipment, plus tractor expenses, plus labor. Much pasture is on land that is not accessible to machinery, or is very stony. It took about an hour to plow an acre, on average, for this project. With tractor and labor costs, that is about $30 + labor ($20/hr for a farmer’s time is a lowball estimate). We calculate $50 per pass for each acre. Add in the purchase and maintenance of the plow, and to cover the four recommended passes, the cost with a purchased plow would be $235.
These costs could be offset if you were able to rent out the plow, you have a kid who likes to (and can!) drive the tractor, etc, but there’s still an expense to it. There are also questions about time and other resources. For example, where the climate shortens the growing season, taking the time to plow might be more difficult. In those same colder regions, organic matter decomposition is slowed, yielding soils which may retain more of the organic matter deposited. Overall, the comparison is between the expense and the resources required, and the value or benefit provided. These pieces of information can help farmers reach decisions about management practices.
Either way, we’re interested in learning more, so we appreciate the discussion that is taking place. Thank you for contributing.
The article says “keyline plowing didn’t change soil or forage quality on these four farms”. How was forage quality measured?
Good question. We collected composite forage samples (clipped from multiple areas around the pasture), and sent them for analysis to Dairy One in Ithaca. There is a long list of analyses below.
Forage samples were collected when we went to get soil samples. We also rated the pasture conditions based on the NRCS system of Pasture Condition Scoring, ranking them on a 1-5 scale. Farmers were also asked if they saw any changes in forage quality and production.
Thanks for asking, and hope this helps! Please let us know if there’s anything else.
The long list:
Forage Samples were analyzed for:
% Moisture, % Dry Matter, % Crude Protein, % Available Protein, % ADICP, % Adjusted Crude Protein, Soluble and Degradable Protein as % of Crude Protein, %NDICP, % Acid Detergent Fiber, % Neutral Detergent Fiber, % Lignin, % NFCC, % Starch, % Water Soluble Carbs, % Simple Sugars,
% Crude Fat, % Ash, % TDN, Net Energies, Relative Feed Value and %s of Ca, P, Mg, K, S, and Cl, as well as % Lysine and % Methionine.
I’m very much interested in this topic as a tool to improve my land. I would like to see opinions from Mark Krawczyk (since he is selling the plows and the system) and Abe Collins on the findings and what else could be causing a non-response. I think it would good to have dialogue about this.
Thank you for sharing this information. I just heard Geoff Lawton mention that too much key line plowing can cut the mycelial threads in the soil. I had never heard that before, so thought to mention in this instance.
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