Fjordworks: Plowing the Market Garden
by Stephen Leslie with technical assistance provided by Kerry Gawalt, both of Cedar Mountain Farm at Cobb Hill co-housing in Hartland, VT.
Meditations on the Art and Science of the Moldboard Plow
PART ONE: To Plow or Not to Plow?
The plow is a tool that is as old as agriculture itself. In many parts of the world people can still be found tilling the soil with primitive “scratch” plows with a hardened wooden point pulled behind oxen, buffalo, donkeys, or horses. The invention in 18th Century England of the cast-iron moldboard plow constituted the beginnings of the modern agricultural revolution. It allowed farmers to work heavier soil types unsuitable to the scratch plow or wooden moldboards and, once coupled with an efficient harness system for hitching to horses, greatly expanded the amount of land that could be tilled in a season.
Moldboard plows fashioned of wood were already in use by farmers of the Roman Empire. The earliest known moldboard plows date back to Ancient China of the Third Century BCE. Known as kuan, these plowshares were fabricated out of malleable cast iron. They featured a central ridge terminating in a sharp point designed to cut the soil and wings which sloped up towards the center to throw the soil off the face of the share and reduce friction. This type of plow was first brought to Holland in the 17th Century and was probably the first iron plow to be seen in Europe. The Chinese plow may have been the inspiration for the rapid improvements that occurred in European designs thereafter. The new Dutch plows had a curved wooden moldboard reinforced with an iron point and cutting edge.
The first routine use of the moldboard plow in Northern Europe dates back to the early 9th century, a time period that corresponds to the widespread adoption of the three-field crop rotation scheme of cereal grains, legumes (peas, beans, lentils), and fallow. This period marked the beginning of a gradual transition from oxen to horse as the principal mode of draft power on the farm. Prior to this, a two-field rotation had been common practice, but the adoption of horse power over oxen required a more intensive land use pattern because of the horse’s higher feeding requirements. In compensation, the work horse provided a faster, longer-lived, more versatile form of motive traction.
The development of the steel moldboard plow by John Deere allowed early 19th Century American farmers to turn over two acres of sod in a day (prior to this an acre was the approximate measure of how much a team of oxen or horses could be expected to plow in one day). This might not sound like much compared to the 20-30 acres that can now be typically plowed in a day with a tractor, but if you consider the capital investment necessary to own the tractor, the team of horses hitched to this elegantly simple implement begins to make sense to the small scale producer.
For centuries, primary tillage for the production of annual crops has traditionally begun with a moldboard plow and even today the moldboard is still the basic utilitarian tool for soil and crop management on many small farms. Even though plowing is a common task it requires attention and skill. True mastery of the horse-drawn walking plow constitutes an art form. You have to know the intricacies of the tool and be a highly competent teamster to be effective. It can take years of practice. Prior to the introduction of tractors on the estates of Great Britain the plowman held an elevated position distinct from all other farm laborers. In this series of articles we will look at specific applications of both horse-drawn walking and riding plows in the management of a market garden.
In a horse-powered market garden in the 1- to 10-acre range the moldboard plow can still serve us very well as one valuable component within a whole tool kit of tillage methods. In the market garden the plow is used principally to turn in crop residue or cover crops with the intention of preparing the ground to sow new seeds. In these instances, the plow is often the most effective tool the horse-powered farmer has on hand for beginning the process of creating a fine seed bed.
The most often heard criticism of the moldboard plow is that its repeated use results in the formation of a plow pan (also known as hard pan) — an impenetrable floor just below the maximum depth of the share. This criticism needs to be balanced by considering the alternative methods of tillage.
The years following World War II ushered in what are surely the most rapid and radical changes in the history of agriculture. Farmers in the mid-west had only recently emerged from the devastating effects of the Dust Bowl years. In 1945 USDA agronomist Edward Faulkner wrote his treatise ‘A Plowman’s Folly’ in which he extolled the virtues of the disc plow. He chronicled the transition of the soil of his own farm — land that had been conventionally plowed for many years — to the alternative methods of using a disc plow and disc harrow to incorporate organic matter on the surface instead of burying it with the moldboard. Faulkner had many valid criticisms of the over-use of the moldboard plow and in many ways he was ahead of his time. He was often demonized by his contemporaries for his advocacy of alternative methods, though today many farmers follow his methods and solely rely on disc harrows, disc plows, field cultivators, or more recently, No-Till practices, to prepare the ground for their crops.
One of the most common tillage tools used on contemporary conventional and organic market gardens is the rotovator — a tractor-mounted rototiller. This tillage tool has the great advantage of reducing the number of implements and passes required to form a seedbed. In just one or two passes it can turn an over-grown garden bed into a perfect seedbed for waiting transplants. The tractor mounted rototiller rotates the tines through the soil by means of the PTO (power-take-off unit). In order to effectively till the soil the garden tractor is put in low gear and the implement is run at high speed — generally in the range of 2300 RPMs (revolutions per minute). The rotovator can be a useful tool, but if not employed judiciously it will eventually have detrimental effects on soil organisms and structure.
The intermittent use of the plow within the context of multiple crop rotations is a far cry from the routine seasonal turning of hundreds or even thousands of acres for the production of commodity field crops. On the small diversified farm the plow can be utilized strategically to actually aid in the quest to avoid erosion, increase soil organic matter, and maximize retention of soil moisture and nutrients precisely because of its ability to help the farmer manage the extensive use of cover crops.
At Cedar Mountain Farm, beginning in 1997 and continuing over the course of several years, we made the transition from tractor to all-horse-drawn implements in our market garden. Once we became 100% horse-powered the difference in soil tilth was quite palpable. Now a section of the garden that is spread, plowed, disced, harrowed, and cultivated with the horses is so friable you can plunge your hand deep into the loam, whereas in our tractor-powered phase, anywhere the tractor wheels had rolled — 3” below the ground was like pavement and the seedlings did not prosper. Even when the horses travel at a faster speed than the garden tractor the plows and harrows do not work the soil nearly as aggressively as tractor-powered tillage tools. The soil flora and fauna are not nearly as disturbed by the horse-drawn implements as they are by being run through such implements as rotovator or even the slower turning soil spader. And without the intermittent use of a chisel plow, the rotovator will form its own species of hard pan — as will a disc-plow and a disc harrow. On the balance, our experience has been that the fieldwork accomplished with the horse-drawn implements is gentler upon the ground even given the fact that we occasionally have to make multiple passes with secondary tillage implements to achieve acceptable results.
Whether or not the regular use of the plow will lead to hard pan is also a factor of your soil type. For the farm with a sandy or gravely loam the danger of creating a permanent plow pan with the moldboard is not as relevant as it is for the farmer working a clay or silt loam. On heavier soils the farmer has to be much more discerning about when to plow, as plowing when such unforgiving soil is too wet will haunt one for the rest of the season with cinder-like clods that never seem to break apart. Even when saturated, lighter sandier soils are less prone to the “smearing” effect of the plow (a smooth shiny appearance to the trough of the furrow that suggests the ground is too wet to be worked). In a dry year deeper spring plowing in a lighter soil might even help reduce the filtration of moisture back down through to the parent-rock as the dry of summer comes on.
The concerns stemming from issues of plow pan are perhaps most relevant to farms with deep glacial banks of topsoil such as are found in the Upper Midwest. Under those conditions, repeated plowing at the same depth may cut off the plant root zone from access to nutrients deeper down and affect the percolation of moisture through to these deeper zones. Here in New England most farmers are lucky to have 10” of quality topsoil. However, on any farm, varying the depth of successive tillage on any given section within a planned rotation of crops is a reflection of good common sense. In such a rotation, depth and type of tillage can be fine-tuned to best accommodate the needs of particular crops. For instance, if we have a section that was fall planted to oats and peas into which we are intending to transplant spring brassica, we know we can get by with simply discing and harrowing prior to planting because the transplants won’t be bothered by the resulting surface crop residue of the winter-killed cover crop. But if we are direct-seeding carrots into a section that has a catch-crop of over-wintered rye we will need to plow that in several weeks before the planting date in order to break down the rye’s seed-germination-inhibiting qualities and to have the crop residue digested into the soil to facilitate making a fine seed bed (we will also factor in enough time to get in at least a couple of stale- bed harrow passes prior to seeding to help reduce weed pressure).
There was once an astounding number and variety of horse-drawn plows manufactured in North America — a plow for virtually every arable soil type on the continent. The nature of live horse power encouraged this kind of ingenious customized design because horses pulling a plow cannot power their way through obstructions the way a tractor can. The modifications of horse-drawn plow designs enabled farmers to work any kind of soil capable of yielding a crop. The majority of these walking and riding plows were mass-produced between 1880 and World War II. Many of these plows are still serviceable, with replacement shares and parts available through brand equipment dealers and vintage equipment specialists. There are also several innovative lines of new horse-drawn plows being produced. The small companies that manufacture these plows are now finding an increased demand for them all across North America and as far away as Europe. In part two of this series we will examine how some of these old and new plows are being utilized on contemporary horse-powered market gardens.
END OF PART ONE