Turning Dirt Part Two: Plows for Food-Plot Tractors

By Mark Trudeau

In this series of articles, The Whitetail Institute’s agricultural expert, Mark Trudeau, passes along his decades of real-world experience in farming and related matters to our Field Testers. In his last segment of “Turning Dirt,” Mark provided his insight to help first time tractor buyers shop for the right tractors to fit their needs. In this segment, Mark discusses plows, when they should and should not be used, and how to choose the right plow for different applications. In later segments, Mark will discuss other tractor implements for working soil and doing other food-plot work.

In the last segment, we discussed how to approach buying your first tractor for food-plot use. Once you have your tractor, you’ll need to attach implements to it to do the work you want it to do, and as food plotters, our first physical step in preparing a proper seedbed will be to do our initial groundbreaking. There are basically two kinds of implements designed to do that job: plows and discs. In many instances, initial ground breaking “can” be done with a combination of discing and, when appropriate, herbicides. In tougher situations, though, breaking ground with a disc can be a time-consuming and expensive proposition, since rougher ground may require repeated passes with a disc and still may not work the soil to the optimum degree. In some of these cases, plowing can cut the work load and give a superior result.


From the outset, you need to understand that while plowing may be a great option in some cases, in others it may not. For example, let’s say that your existing food plot is several years old and nearing the end of its life cycle and you are going to replant it with Imperial Whitetail Clover. Since Imperial Whitetail Clover grows in only the top few inches of soil, there’s no reason to turn the ground below that depth — discing just the top few inches of soil will probably be sufficient to work in lime and otherwise start preparing your seedbed for replanting. Consider also what effect plowing might have if you are in an area that receives low or seasonal rainfall. Plowing in such conditions may not be advisable since it can speed up the rate at which the soil loses what little moisture it has. And what if your ground has shallow topsoil? If your topsoil is only two or three inches deep, plowing may be something you actually want to avoid. An example that immediately comes to mind is an assignment the Whitetail Institute’s consulting arm, “A Team Consulting,” recently completed in central Florida. Most of the topsoil on the property had been decimated by years of overgrazing by cattle. To make matters worse, it was only 2- 3 inches deep, and below it was nothing but sand. It can take decades to recreate even one inch of top soil, and what little that landowner had left was as precious to him as gold. Since plowing would have destroyed the remaining top soil by mixing it with the sand below, we advised the landowner to avoid plowing at all costs. My point is not to tell you that you should never plow. I just want you to approach the issue in an informed manner. Make sure before you invest in a plow that you really need to plow and that it won’t end up causing more problems than it solves. If you do decide that plowing is appropriate given your soil and weather conditions, you’ll likely find it an effective and efficient way to do hard, initial groundbreaking. Let’s say, for example, that you are in an area that receives the sort of regular, abundant rainfall common throughout most of the eastern half of the United States. Let’s also say that you are going to be preparing a seedbed in a site that has either never or not recently been worked, and that you are planning on planting a deeply rooted forage such as Imperial Chicory Plus, Alfa Rack Plus, “Chic” Magnet or Extreme. In such cases, plowing can really speed things up, save you money and maximize the quality of your planting results.

 Let’s start out with a discussion of plow types. There are basically three: disc plows, moldboard plows and chisel plows.

Disc Plows: In earlier days of mechanized agriculture, most plows were disc plows. These are pretty simple implements. The cutting tool in a disc-plow assembly is basically just a big, round disc similar to the cutting tools on disc implements. Disc plows usually have either one or two discs mounted to the implement’s main frame.

Moldboard Plows: Also commonly referred to as “bottom plows” and “breaking plows,” moldboard plows are the next generation of plows after disc plows. The most immediately recognizable difference is the shape of the tool that actually turns the soil – the tool on a moldboard plow is longer and shovel-shaped instead of a disc. Moldboard plows consist of four standard components. They can also be had with optional features that are very desirable, but the basic components are: 1. The “moldboard” — a shovel-like curved blade that actually turns the soil, 2. The “plow point” or “plow tip” — the bottom of the moldboard that cuts the bottom of the plow furrow and can be replaced as it wears out through use, 3. The “plow shear” — the front edge of the moldboard that cuts the side of the plow furrow and can be replaced as it wears out through use, and 4. The “tag wheel” or “slide” that runs along inside the plow furrow as the implement is pulled. One optional component available for moldboard plows is coulter blades. If you are working up an existing food plot for replanting, you can usually do fine plowing without coulters, but if you’re plowing new ground, coulter blades can reduce the time and horsepower it takes to do the job. Coulters are essentially round blades like discs, but unlike discs which are concave, coulters are either flat or wavy. On a coulter-equipped plow, the coulters are mounted with a bearing to the implement’s frame directly in front of the moldboards, or more specifically in front of the plow shears. Their purpose is to make an initial slice in the surface of the soil just ahead of the moldboards, in effect pre-cutting the surface of the ground before the moldboards arrive. Coulter blades can be had with either smooth or notched cutting edges. Smooth blades work well for plowing areas covered in grass, turf or other tender rooted vegetation, but notched-edged blades are much more effective for slicing through briars, heavy roots and other woody matter often encountered when plowing fallow ground in the woods for the first time or old fields. Another optional item available for moldboard plows is “turnouts”. These mount at the top of each moldboard and are VERY effective in helping get a better turn on the soil, especially in sod. A third optional component available for moldboard plows is a “trip” function. I have found these to be of great value. If you hit a big underground rock or root with a plow equipped with a trip, the force will trigger the trip, allowing the plow to pop up instead of breaking or becoming lodged under the impediment. If the trip is triggered, all you have to do to reset the plow is back the tractor up a little until you can lift the plow implement, back the tractor up a little more, lower the implement back down onto a relatively hard surface (often the very thing that caused the trip to spring), and then back the tractor up a little more. This will reset the plow and the trip to their operating positions, and you can then resume plowing. Not all moldboard plows come with a trip feature, but take it from me — it’s a highly desirable option. Moldboard plows come in various sizes, the most common being 12, 14 or 16-inch models as measured off the plow’s tip. For food-plot tractors, you’ll do fine with a 12-inch model.
Chisel Plows: Chisel plows are simply long, curved shanks with replaceable points on their ends. If you decide to chisel plow, here’s a tip: if the surface of the ground is covered with debris, it can be a good idea to disc first. Chisel plows are curved with the concave toward the front. As a result, they tend to collect vegetation, sticks and other such surface debris as they move along. Discing first to chop up surface debris can help keep a chisel plow from clogging.

A Note about Subsoilers: Subsoilers are really only appropriate for large, agricultural farms and have little purpose in food plotting, and I only mention them here because you may have heard of them and wanted to know what they are. They’re very similar to chisel plows, but the shanks on a subsoiler are longer, usually 24-36 inches long, and can break ground as deep as 18-24 inches. Plowing with a subsoiler allows more moisture to go deeper into the ground. However, plowing to that depth is rarely if ever necessary when planting food plots. Also, they require a lot more horsepower to pull — about 35-40 Hp per shank, which may be above the power limits of most compact and utility tractors.


Disc plows, moldboard plows and chisel plows all break ground to a maximum depth, which is determined by the size of the cutting tool on each plow assembly on the implement. However, as I mentioned earlier, each uses a uniquely shaped tool to actually move the dirt. As a result, each leaves the soil in a different position (for lack of a better word) after it passes, and that is the most critical issue when deciding what type of plow you need. Again, it is absolutely crucial that you understand what each type plow does to the soil if you are to choose the correct kind of plow for your particular application. Let’s look at what each type of plow does to the soil between the moment the plow makes its initial cut and when it finishes its work.

Disc plows basically do the same thing a discing implement does, just deeper. The tool that the plow assembly uses to cut the ground is a disc that rolls the soil over (but not in a column the way a moldboard plow does) to a given depth (the radius of the disc blade) and then mixes it together.

Moldboard plows do not mix the cut soil the way disc plows do. Instead, they lift the soil as a column, invert it (turn the entire column upside down as a unit) and set it back down on its head in an adjacent plow furrow. As a result, surface soil is placed at the bottom of the column, the lowest soil lifted is placed on top, and the soil in the middle of the column is returned to about its original depth. A moldboard plow is absolutely great for turning over new ground covered in sod or other shallow-rooted vegetation. In such cases, a moldboard plow lifts the soil as a unit and then flips it, putting surface vegetation far below the surface and bringing up lower soil. As a result, existing surface vegetation is eliminated in one pass, and nutrients that have washed into lower soil levels are returned to the surface. In that way, a moldboard plow can do in one pass what would likely take multiple passes with a disc, perhaps even in conjunction with herbicide applications, to accomplish — to clear the plot’s surface of vegetation and leave only loosened soil on top.

Chisel plows also do a great job of breaking hardpan, but they neither mix the disturbed soil as thoroughly as disc plows nor invert it as a column the way moldboard plows do. Instead, they just break up compaction, leaving the soil looser but pretty much where it was. A chisel plow is an excellent choice if you want to break up hardpan to allow more moisture to get into the ground, even if you’ve already had a food plot growing on the site for a few years. It’s also a great option for loosening lower layers of soil if you are planning on planting deeply rooted forages such as Imperial Whitetail Chicory Plus, Alfa-Rack Plus, “Chic” Magnet or Extreme. So, in basic terms, you need to remember that a disc plow breaks and mixes the soil, a moldboard plow breaks, lifts and then inverts the soil, and a chisel plow breaks up the soil and leaves it pretty much where it was.


Now that you know what types of plows are available and what each does to the soil, let’s cover how different types and sizes are commonly referred to in conversation. Basically, all plowing implements consist of a main frame to which varying numbers of separate plowing assemblies are mounted. Each type of plow is described by its number of attached ground-turning assemblies. With moldboard plows, this number is described in “bottoms” and with chisel plows in “shanks.” The size of the shovel on a moldboard plow is further described in inches as measured from the plow’s tip. For example, if someone says that he has a “12-inch, two-bottom plow,” you’ll know he has a moldboard plow with two separate plowing assemblies mounted to its main frame, and that each moldboard is of twelve-inch size as measured from the moldboard’s tip. You’ll also know that as the implement is pulled through the ground, it will simultaneously cut two furrows and invert each furrow’s soil into an adjacent furrow. Likewise, you’ll know that a “six-shank plow” is a chisel plow that will simultaneously cut six furrows as it passes. You’ll also know that as the implement is pulled through the soil, it will break up the hardpan and leave the soil pretty much where it was instead of mixing or inverting it.


Plows and other implements that tractors pull attach to tractors in one of two ways — they are either “three-point-hitch mounted” or “semi-mounted.” Three-point-hitch is the common attachment method for two- and three-bottom plows, which are best suited for food-plot work with compact and utility tractors. Three-point-hitch-mounted implements attach to a tractor’s lift arms. Implement height is adjusted by the lift arms and an adjustable top link on the tractor. Three-point-hitch implements have either a smaller tag wheel or a flat, steel slide that is attached to the rear of the implement and that runs inside or along the edge of the plow furrow as the implement works. Semi-mounted implements are larger and better suited to commercial farming operations than food plot work. They also attach to a tractor by way of the tractor’s lift arms, which connect to the front of the implement’s main frame. Implement height is adjusted separately in the front and back. Front implement height is adjusted with the tractor’s lift arms, and rear height by a separate hydraulic cylinder that raises and lowers the tag wheel. The tag wheel on a semimounted implement is much larger than the tag wheel on a two- or three-bottom plow; it’s usually an air-filled tire, and, unlike the smaller implement’s tag wheel, a semi-mounted implement’s tag wheel runs beside the implement on level ground.


The biggest variable that will control how large a plow implement you select is the ability of your tractor to pull it. As we discussed in the last segment of “Turning Dirt,” a tractor’s ability to do work is expressed in horsepower, which is measured at either of two places depending on the type of work the tractor will be doing. The tractor’s capacity to turn rotational implements such as brush cutters and post-hole diggers is expressed as its “PTO Hp” (power-take-off-unit horsepower), and its ability to pull implements such as plows and discs is expressed as its “engine Hp.” Here, we are concerned with engine Hp. Broadly speaking, it takes 18 – 20 engine Hp to pull each plowing assembly on a moldboard plow implement, and 10-12 engine Hp per plowing assembly on a chisel plow. Be sure you read that carefully — I said “18 – 20 engine Hp to pull each plowing assembly on the implement,” not to pull the whole implement. For example, it will take a tractor with 36- 40 engine Hp to pull a two-bottom plow (18-20 engine Hp per plow assembly on the implement). Most tractors in the compact and utility categories produce engine Hp in this range. Remember also that we mentioned in the last segment of “Turning Dirt” that you should try to avoid the temptation to get an implement so large that your tractor has to continually operate at peak output to pull it because such constant, repetitive strain will prematurely age your tractor.


Now that you’re an expert in food-plot-tractor and plowing-implement terminology, capabilities and functions, I’ll talk to you as the expert you are. Assuming that you have a compact or utility tractor capable of delivering at least 18-20 engine Hp per plow (again, not per implement, but per plowing assembly mounted to the implement’s main frame), you will likely be best served with a 12-inch, two-bottom or three-bottom plow if you want to break the hardpan and invert the soil, or a two-shank plow if you just want to break up the hardpan. Smaller implements such as these usually attach by three point- hitch and are commonly available in a price range of $250 - $500 for a used model in good shape. (You can read Part One of the “Turning Dirt” series by going to www.whitetailinstitute.com and clicking on “Whitetail News Volume 16, No. 3.”)