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Keyline Plowing: What is it? Does it work?

RachelsBelieveItOrNotOMeterWhen I first heard of keyline plowing, and that it could build 8 or more inches of topsoil in a year, my “Believe-It-Or-Not-O-Meter” went off.  Decades of studying soil, its chemical properties, the complicated ins and outs of how soil changes and supports plant growth, combined to tell me “This just isn’t possible.”

To find out if it was true, I had to find out: What is keyline plowing?

Keyline plowing is a form of subsoiling.  Subsoilers are implements used to loosen and break up soils to double the 6 to 8 inch depths that a traditional disk harrow reaches.  The tool used for keyline plowing is the Yeoman’s plow, a subsoiler with very thin shanks.  Created in the 1950s by P.A. Yeoman, an Australian mining engineer and farmer, it was designed to  lift and aerate the soil while limiting soil disturbance to minimize oxidation of organic matter.

KeypointYeoman used his plow as part of a landscape design with an emphasis on addressing conservation issues facing Australian farmland where erosion and drought are major challenges.  His idea was to capture water and move it across the landscape using “Keylines.” The keyline is like a contour line, in that it follows the topography of the land. It is based off the keypoint, described by practitioners as “the highest point on the landscape where one can cost effectively hold water.”  That’s where the slope changes from convex, where it sheds water, to concave, where it collects water. Following the line of that point around the landscape produces a kind of topographical etching of the land. The keyline plowing pattern, following the keyline across the landscape, creates a drainage or water flow system to move water from wet areas to dry areas.

Where’s the Data?

Photo from
Photo from of a keylined pasture.

Proponents of the Yeoman’s plow and keyline design cite a number of benefits.  They say it reduces compaction, and can build up to a foot of topsoil per year.  It is also touted as a method for increasing carbon sequestration. It seemed strange to me that simply ripping thin lines through a pasture could do all that.  As a soil scientist, I look for data and so I began the search.  I found nothing online, in journals, or from farmers who had tried it.

I attended a two-day course on keyline plowing with Darren Doherty, an expert on Keyline plowing from Down Under.  I asked him for some data. He said that in one case, soil was tested before and after keyline plowing, and its CEC (capability to hold nutrients) went from 6 cmolc/kg to 12 cmolc/kg. But they also limed the soil while they keylined it. We all know that when soil pH goes up, the CEC goes up too. So the change was likely a result of the lime and his data were meaningless.

Waldorf and StatlerHere’s where I start turning into one of the two grumpy Muppets in the box seat. The buzzing from my Believe-It-Or-Not-O-Meter is going off like a smoke detector. Deep breaths, and we’ll get to the bottom of this.

I decided to study the practice myself and got together with a team from University of Vermont, including fellow soil scientist Josef Gorres and graduate student Bridgett Hilshey. In Vermont, four dairy farmers agreed to let us keyline plow their pastures. We partnered with Mark Krawcyk of Keyline Vermont. Mark is a wonderful guy, with a soft, clear way of explaining things. He worked with each of the farmers, showing them how he found the keyline in their pastures. He also keyline plowed each of the target pastures four times over two summers, following the recommended protocol for keyline plowing.

Mark running the Keyline plow in our experiment.
Mark running the Keyline plow in our experiment. Photo courtesy of Jennifer Colby.

Even with Mark’s conservative pricing structure, it cost approximately $160/acre to plow the recommended four times.  Add to that the cost of running the tractor pulling the plow, and the total cost for the treatment was $280/acre.

The results

To measure the effects of keyline plowing, we collected soil and forage samples from the keyline plowed pastures and from similar adjacent pastures. For good measure, we also tested penetrometer resistance and rated the pastures’ conditions. We sampled before, during, and after the two years of plowing.

With thousands of soil samples, and hundreds of readings and scores, we found nothing; no increased organic matter, no changes in penetrometer resistance, no change whatsoever, unless you measure in worms. We did find more worms in our treated pastures.

There are folks out there, who are very nice people, who believe in the use of the keyline plow, who will be alarmed at these results. So next week, we’ll describe more about this trial and its results. We’ll even tell you more about worms and why more of them may not be as positive a result as you might think. Down the road we’ll also share some results from a study on the use of keyline plowing to enhance carbon sequestration. In the meantime, if you have experience with keyline plowing, and you have any data, please share it with us!

Read part 2 in this series here

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Rachel Gilker
Rachel Gilker
Rachel's interest in sustainable agriculture and grazing has deep roots in the soil. She's been following that passion around the world, working on an ancient Nabatean farm in the Negev, and with farmers in West Africa's Niger. After returning to the US, Rachel received her M.S. and Ph.D. in agronomy and soil science from the University of Maryland. For her doctoral research, Rachel spent 3 years working with Maryland dairy farmers using management intensive grazing. She then began her work with grass farmers, a source of joy and a journey of discovery.


  1. The keyline plow (I always want to type “key lime” plow) discussion seems to fit in the “hammer and nails” category: If all you have is a hammer, all your problems look like nails.

    As with any system, it will come into equilibrium over time given that all parts of the system stay the same – even though the system may not be operating at its optimum state. However, when one part of a system changes, the other parts of the system will change in response to the original change. In the instance of an agricultural system, the initial change could be the use of a keyline plow. As the information on the keyline plow states, the plow is basically a subsoiler and it is “… used to loosen and break up soils to double the 6 to 8 inch depths that a traditional disk harrow reaches.” This kind of subsoiling operation would benefit situations where there is a compacted layer within that 12″ to 16″ depth that is restricting root and water penetration. Also, the plow would seem to have some positive effect on soil aeration and, therefore, improve root functioning and microbiology. However, if compaction and aeration are not what is causing the system to be out of optimization, then using a keyline plow would probably have negligible results.

    A system needs to be evaluated from a Hazard Analysis & Critical Control Points (HACCP) standpoint; i.e., every part of the system needs to be evaluated to determine the impact of the management scheme on the optimum functioning of every part of the agricultural system. Only after the HACCP evaluation has been thoroughly implemented can a “prescription” be formulated and implemented to bring the system back to optimum production. A keyline plow could be a part of the prescription only if the plow’s effect on the entire system is seen to be needed to solve the particular identified problem that is keeping the entire pasture system at a suboptimal level of production.

    Without a thorough evaluation of each part of the entire agricultural system, the use of a keyline plow falls under the category of “trial and error”. Confounding the evaluation of the efficacy of the plow could be that its effects on the system may actually be somewhat beneficial but that its use is not really solving the weak link in the system and the system would continue to operate below its optimum level, albeit at a higher level than before the plow’s use but still at a suboptimum level.

  2. Thanks again Rachel for another interesting article. I’m very interested the “keyline” concept and also Geoff Lawton’s swale concepts which I believe are somewhat similar.
    I think all of the comments are also quite insightful, especially Owen’s. The bottom line is that every situation is unique and blanket statements as to wether something works or not, are not beneficial to the whole. You can say it didn’t work with your methodology and with your initial conditions, but that may not be applicable across the board.
    I’m hoping to attend a keyline course that Owen is teaching in Carbondale, CO next month if I can scrape the cash together. I’m hopeful that I can learn more of the “ins &outs” of keyline design and get handle on the situations where the phrase “it depends” means success or failure. Or probably better worded – response vs. no response.

  3. Greetings,

    Thank you Rachel for your interest, attention, and especially ACTION around this topic. Far to few of us interested are effectively in a position to organize credible research about it, so hat is off for that!

    In my own work with Keyline systems and Yeomans’ plow sub-soiling (a consultant/educator and one of Darren Doherty’s mentees in the U.S.) with many different clients, we have thusfar always experienced improvements and different degrees of success. So, will have to add to the further accounts of success already offered in these comments (Chris Gill, Darren Doherty…)

    One important and sometimes overlooked factor is the beginning condition of the area you are treating. You don’t give any indication how healthy an initial condition you began with in your study, which perhaps you will address in a future article. The most improvements will obviously come from situations where beginning conditions are poor to sub-healthy. Where you are already happy with conditions in the first place it probably makes little sense to apply the sub-soiler, as even if there are improvements they are less likely to justify the expense. I know a livestock operator in Saskatchewan who experimented with sub-soiling his already incredibly healthy (through holistic grazing practice) pasture in places and he observed a decline in brix reading afterwards. Could be a case of ‘if it’s not broke’…

    That said, in less than healthy situations, my experience is that this can be a highly effective tool for decisively crossing a threshold to move towards significant improvement in ‘stuck’ systems. Sometimes astoundingly so. One small example, a client (who is also an ecologist) in Pecos, New Mexico who had a pasture that was resisting changes he attempted (weeding, seeding, etc) over many years. Flooding rains would periodically wash away any litter layer he could slowly build. After using the Yeomans plow on Keyline Pattern Cultivation he again experienced flooding rains, and this time no litter loss (since the water was soaking into the soil rather than running off the land), and huge amounts of seed recruitment in response. The system shifted completely.

    Another example where I do have some specific data are from southwestern New Mexico, where we used the keyline subsoiling treatment on an abandoned cotton farm that had been in a bare ground state for over 20 years subsequent to abandonment. Here I did sample 5 separate areas before and after for the following indicators, with the following results averaged across the 5 areas (soils were clay loams) :
    pH dropped an average of 0.3
    Salinity dropped 59%
    Compaction reduced 70%
    Rate of Water Infiltration increased to 11 times faster
    Organic Matter increased 0.4 %

    Across the whole site plant cover went from less than 5% to above 80%. Soil aggregates improved structure. All ecosystem processes marked improvements. Went from a barren wasteland to an environment supporting frogs, ground nesting birds, and predators in about a year. Can youtube ‘water and transformation in drylands – Owen Hablutzel’ for more…

    In any case my overall impression is that though I have heard of situations where little or no improvement is found (sometimes a result of too little rain following closely enough), on the whole my experience has been that more cases result in improvement than not.

    I won’t claim ‘a foot’ of topsoil per year, but neither have I ever heard such a claim by anyone out there actually working in the field (which makes me wonder where you heard this claim your article suggests) Nor will I claim even 8 inches a year, which your article also suggests is a claim being made by Keyline supporters. Of course you would be remiss not to be skeptical or want to see data. I would suggest however that nobody responsible is actually making the claim that Keyline subsoiling increases topsoil depth 8 inches a year, as your article claims. If so, they radically reduce the process of what actually happened at Abe Collins’ place in Vermont (which is where I believe this number of 8 inches has come from). The topsoil built by Abe Collins that year (be it 8 inches or some other number) was NOT built by the Yeomans’ plow alone, and to my knowledge he never made this claim. In fact Abe used a combination of keyline plowing, holistic high-density grazing, field applications of bio-stimulant such as raw milk and molasses, and perhaps more treatment options that i’m unable to recall at the moment. So truthfully, nobody informed has been making the claims for Keyline plowing that the article suggests are being made, so the article risks presenting a bit of a straw man to argue against.

    Anyhow, not a big quibble, and am happy to see the research you are doing going forward. Thank you for this contribution to the wider conversations that can help us all find effective tools, skills, and actions to address our increasingly complex situations.

    Thanks again Ms. Gilker!

  4. Hi Rachel,
    Thanks for doing this work. This is a subject that I’ve been interested in for a while.
    Can you provide more details about the pastures that you ran these experiments on?
    We obviously don’t have the evidence to prove this right now, but it seems that soils, climate and forage species would make a pretty big difference. In the some instances, plants are simply not going to be very limited by rooting depth or water distribution. In others, that may be the key factor holding back plant productivity.

    I’d be pretty surprised if there wasn’t improvement from keylining a pasture with lots of alfalfa, on sandy upland soil with a hardpan layer at 10″.
    Similarly, I’d be pretty surprised if a bluegrass-clover pasture on wet, bottomland clay gave much response.

    Look forward to hearing more.

  5. Dear Mrs Gilker,

    We ranch in the deserts of far-West Texas and have used the Yeomans Keyline plow with great success.

    $280.00 per acre? Not counting amortization of tractor and plow but only fuel, repairs (tires, motor maintenance etc.) and labor, the cost is about $10.00/acre.

    One treatment is all that I would recommend, although desert soils will reseal and unless plants are growing by then further treatment may be needed in years to come. Four treatments is complete overkill.

    We have treated about 3,500-acres so far.

    You must use a transit to set your contours; laser transit is best.

    The reason this device helps desert grass plants is because (1) it opens crusted desert soil to increase water penetration and (2) the pattern spreads and slows water. It makes scant desert rainfall more effective.

    I have never not seen plants respond to this treatment: some slightly and some dramatically.

    It has to rain to work.

    Where there are colonies of grass still alive the result can be amazing and where the ground is dead and bare the result is much less but still there is response.

    If you get plant roots to penetrate dead dirt and deposit carbon, you are creating topsoil. How much how fast I will leave to the theorists: I just watch the grasses and forbs green up and grow. I have dug many test holes after rains have fallen and assure you water penetration is all the way to the bottom and multiples of normal soaking.

    The Keyline Plow is a small add-on to cattle used holistically so if there is no grazing this will not work over long terms.

    It is not magic and wild claims should be taken with caution: but absolutely, this thing works.

    Please visit this site to see more:


    Christopher Gill
    Circle Ranch
    Van Horn Texas

  6. G’day,

    As someone who’s done a lot of Keyline system advocacy, perhaps the most since P.A. Yeomans himself and especially internationally, I am naturally curious as to the process used to develop a deeper rhizosphere in these experiments, which is ostensibly the outcome I seek when using the tool of Keyline Pattern Cultivation. Mark Krawczyk has attended a few of our Heenan Doherty workshops over the years and is a very thorough person, as anyone who works closely with the likes of Dave Jacke would be.

    I am also aware of the work done on a Californian client’s property, Nicasio Native Grass Ranch, where as part of the research project for the Marin Carbon Project, Professor Wendee Silver’s findings were also not very encouraging when it came to Keyline Pattern Cultivation. In this case I do know that the what I would describe as a proper process was followed and that the results were less than encouraging when it came to soil carbon sequestration, and this is where the tool of Holistic Management planned grazing was also applied as is in my opinion best practice. I’ve not seen the final findings of this research and not been back to this site to witness first hand the changes, if any, that have occurred in this case as a result of the use of the Keyline Plow.

    In my own experience, when the Keyline Plow (and other similar implements) are used they are not a silver bullet. Rather for the results to be optimal one needs to manage the pasture recovery following cultivation and that the timing of both cultivation and the grazing/mowing that is a important part of the process is to me quite important in order to warrant the expense. Certainly there are many properties that I’ve worked on over the 19 years since I got my first Keyline Plow that have not had soils develop as one would have hoped however I can usually point to the lack of due diligence when it comes to the application of the timing and process that has been the cause of this, and this is on a myriad of sites, climates and production systems, though in most cases in pastoral systems.

    On our own place the proper process has been undertaken and the results have been quite compelling and we’ve published quite a few ‘before and afters’ and the odd video. Have the agronomical outcomes improved, well for a Holistic Management person then I would say yes as many of our goals have been attained though we still have some way to get to where we want to get to and the plow’s use has been but one of the tools used to get there.

    We have increased our soil depth considerably from 2-4″ to 8″-12″. What exactly does this mean by ‘increasing soil depth’? Well from my un-trained, non-scientific mind, it means that the active rhizosphere has deepened and the soil colour has changed considerably and the obvious biological activity (and its by-products) has also increased to the aforementioned depths. Our plant diversity has also increased considerably from around 5 mostly annual species to now around 30 in a 6 year timespan. The function of these species I would say is still that of primary succession, however we are starting to witness a number of native perennial grasses that are higher succession and very long lived and importantly, palatable and therefore a reflection of the inherent increases in fertility.

    In terms of sum biomass before and after (discounting the anomalous ‘Canonical’ La Nina event we went through from June 2010-Sept 2012 {more or less}), we’ve increased pasture yields from around 2.5-3t/ha to 3.5-5t/ha in different zones over our 25 acre (9ha) holding. We have quite varied ground and topography and this in itself is responsible for considerable variations on what is a relatively small site and therefore sample.

    What is perhaps the greatest outcome at our place, and that which we’ve seen repeatedly on a number of site around the world, has been the ability of treated soils to ‘hang on’ longer, that is to stay growing for longer than on untreated sites. Also, as any professional livestock manager would understand and appreciate, that the livestock themselves will more often than not, self-select areas to graze where the treatment has been applied which is very interesting indeed. For people such as Kathy Voth and her work, I would have thought that this is worthy of note as it indicates a degree of self-selection such as happens when particular plants colloquially referred to as ‘weeds’ in most circles are sought out by livestock to apparently service their own mineral and biochemical needs. The use of ‘Free Choice Minerals’ is a somewhat perverse application of a similar self-selection and indeed self-medication.

    With regards the reference to Abe Collins work, and I regard Abe as a friend and colleague, I have only seen photographic evidence of the outcomes of his application of the use of the Keyline Plow and again the outcomes have been similar to that of my own, however the rhizosphere development was considerably greater than ours over a shorter period. I do recall however that he remarked that his soil carbon tests were not encouraging. As land managers we are typically more concerned with the cost benefit of our inputs and that of livestock and pastoral health and so it would be great to have a research scientist following us around but of course in the current paradigm and terms of trade that is clearly not going to happen and so we are stuck in ‘farmer anecdote land’…

    Further to this this discussion is the whole issue of research of Keyline. According to P.A. Yeomans himself, in 1958, the then head of CSIRO and renowned veterinarian, Sir Ian Clunes Ross (who was on the Australian $50 note for nearly 20 years!), sanctioned a wide ranging research project on the whole Keyline system. The following year Sir Ian, following a trip to the US, unfortunately died aged just 60. The CSIRO was then headed by a physicist and the so did the champion of this research project. To my knowledge there have been no wide ranging longitudinal studies into the outcomes of Keyline systems whilst there have been smatterings of smaller projects and this one completed by Rachel Gilker (I went to the trouble of getting her name right!) none have been what I would call comprehensive, though the Marin Carbon Project work did go over a longer period and was evidently quite rigid in its process (I have not seen the final report or paper on this to comment further).

    On this front Keyline Design Course students of HeenanDoherty, Ethan Roland and Mark Krawczyk did apply for a SARE grant a few years back to complete a 3 year study (from memory) on the broad effects of Keyline Pattern Cultivation. This grant was rejected on the grounds that ‘this research has been done before’, to which we all replied “that’s great, where is it ’cause we want to see it as it will save us the effort”. No response was given to this request. Now, clearly I am not an academic and have no wish or desire to be, however I do understand that its unprecedentedly easy to access research papers and I am sure lettered folks such as Ms. Gilker would have found it if there was any such research otherwise they would not have bothered either.

    I applaud any efforts to find truths wherever they can be found as to us integrity and honesty are everything in this world and if we can find that what we know is not what it seems then I have a track record of not having any issue with acknowledging these new-found truths provided they are holistically based, the methodologies for their retrieval are also holistic and thorough and that the treatments under analysis are following the appropriate process accepted by many as optimal.

    Thanks to Ms. Gilker and the team involved for raising this issue and for doing the research that they have. I and I am sure many others look forward to the further release of any outcomes including detail on the treatments, their timing and the conditions, such that we can make for a more informed discussion than we otherwise can at this stage with relatively scant details.

    Thanks and all the best,

    Darren Doherty

  7. Hello Rachel,
    Nice to see some discussion happening on this topic and wishing to share some of my thoughts.
    As I understand keyline is a tool, one of many with a very strong potential in land regeneration.
    Amongst potential regenerative tools are also compost/compost tea, holistic grazing management etc.
    And for me it is clear, all these tools can be used with or without results because in life as in Permaculture, it all DEPENDS…and in this case on MANAGEMENT.
    So the question is: How were the animals/pasture managed during these two years of plowing? How was the soil during plowing (after/before rain/snow? At what depth was it plowed? Were seeds dropped in the furrows? Were chemical applied? Was liquid manure spread?
    Until we get the big picture it will not make sense.
    Best wishes for the exploration of this topic,

  8. Holistic, high stock density, AKA mob grazing is thought to confer the same benefits as Key-line for building top-soil, but I’m not aware of data there either. I’ll be surprised if data does not START coming within a year or two, but In any case, I think we would all be enthusiastic if someone (competent) would compare the two systems side by side.

  9. Thank you for this excellent article. I’ve often wondered how successful use of a keyline plow would be. There always seemed to be more hype then actual research. The results of your research and this article have been very informative. thanks!

  10. Rachel,
    Thanks for doing this research. I’ve been curious about it since Abe Collins visited Wisconsin several years ago plugging the concept of Keyline plowing, but did not have the money to invest in a keyline plow.

    In terms of capturing water, such as using ponds for irrigation, I am still wondering if that is a valuable long term solution? So much water falls on our ground in winter and spring, that it would be nice to capture, store and efficiently utilize it during the summer dry period. I have not done this yet, since all of my land is leased, and the cost to implement is too high, in my estimation, for land I don’t own.

    Regardless, I look forward to the next article on the subject.

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