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Podcast Transcript
For most of human history, growing food depended on one deceptively simple piece of technology.
Over thousands of years, it evolved from little more than a sharpened stick into a machine that could transform entire landscapes, open new regions to farming, and support much larger populations.
Its development helped shape settlement patterns, economies, and even the rise of civilizations.
Learn more about the history of the plow on this episode of Everything Everywhere Daily.
Before you think that this episode will not be interesting, and that a plow is something that isn’t something to get excited about, I’d ask you to hold on for a minute.
Most of us are not farmers. The percentage of people who are actively involved in agriculture today is around 2% in the developed world. However, historically, that number was probably closer to 90%.
The plow isn’t something that most of us are intimately familiar with. Yet it is one of the most important inventions in human history, and that is no exaggeration.
It was the plow that allowed us to develop large-scale agriculture, expand into marginal agricultural lands, and create a food surplus that made modern civilization possible.
Before I get into the plow itself, I should first address the question: why do you need to plow in the first place?
Imagine trying to plant wheat in an undisturbed field covered with grasses, weeds, roots, and the remains of last year’s vegetation. Simply scattering seed onto the surface yields poor, inconsistent results. Most seeds wouldn’t germinate and many would be eaten by birds.
Plowing traditionally performs several jobs at once.
First, it loosens the soil. Compacted soil can make it difficult for seedlings to establish roots. Loosened soil gives roots easier access to water, oxygen, and nutrients.
Second, plowing creates a seedbed. Seeds germinate most reliably when planted at an appropriate depth and surrounded by reasonably loose soil, rather than lying on hard ground.
Third, plowing historically provided weed control. Turning the soil can uproot existing weeds and bury their vegetation.
Fourth, a moldboard plow can bury crop residues, manure, fertilizers, and organic material, mixing them into the upper soil. More on moldboards in a bit….
Finally, fifth, plowing can temporarily alleviate some types of soil compaction and expose soil to air, accelerating biological and chemical processes that release nutrients.
So, there are a host of reasons to turn up the soil before you plant. In fact, this was one of the first things humans figured out when they started planting crops, and it was discovered independently around the world.
The earliest farmers of the Neolithic period did not have plows. They cultivated relatively small plots using digging sticks, stone hoes, and similar hand tools.
This worked surprisingly well for garden-scale agriculture, especially in loose soils. But it was extremely labor-intensive.
A person with a hoe can cultivate only a relatively small area. A hoe is probably the best option for someone today if you just have a small garden plot you want to till; however, if agriculture was going to support larger settlements, farmers needed some way to harness animal power.
The earliest plows were what archaeologists usually call ards, or scratch plows. The ard probably appeared in the ancient Near East sometime during the fourth millennium BC.
An ard was little more than a pointed wooden implement attached to a beam. An ox or other draft animal pulled it through the soil while the farmer guided it from behind.
Instead of turning the soil over, the ard scratched a narrow groove through it. Think of it as a giant animal-powered digging stick.
The great advantage was speed. A farmer could make long furrows far faster than people could prepare the same land with hoes. Fields could therefore become much larger.
The ard was particularly well suited to the relatively light, dry soils of the Mediterranean, Middle East, and parts of southern Asia. Farmers could plow once in one direction and then again at right angles, producing a crosshatched field.
Many of these early ards were pulled by humans. The plow became far more significant when combined with specialized draft animals.
Oxen were particularly important. Cattle could convert grass and crop residues that humans could not digest into mechanical power. A team of oxen could pull an implement much larger than anything a human could operate alone.
The next important development was the plowshare. The plowshare, or just “share,” is the cutting edge that slices horizontally through the soil.
Early plowshares were wooden or tipped with stone or bone and were eventually made of metal. Metal was transformative because soil is extraordinarily abrasive. Wooden points wear down rapidly.
Bronze and especially iron allowed farmers to make thinner, stronger cutting surfaces that penetrated difficult soils. Iron agricultural implements became increasingly common in several ancient civilizations.
China became particularly advanced in the use of iron plow components. Archaeological evidence shows iron plowshares during the Warring States period, roughly 475 to 221 BC. By the Han dynasty, iron plowshares were widely used.
While the plowshare was an advancement, the biggest revolution in plow design was the transition from merely scratching the soil to actually turning it over.
This required the addition of the moldboard. The moldboard is the large, usually metal, piece that lifts the resulting slice of soil, twists it, and flips it to one side.
Instead of merely scratching a groove, the plow cuts out an elongated strip of soil and overturns it. That strip is called a furrow slice. The result is the familiar appearance of a freshly plowed field that you might see today.
The biggest benefit of turning soil over is that it buries weeds, crop residue, and surface vegetation. Instead of merely cutting through them, the moldboard flips the furrow slice over, placing much of that material underneath the soil. This gives the next crop a relatively clean seedbed and was especially valuable before modern herbicides.
It also helps incorporate manure, lime, and other soil additives into the upper soil rather than leaving them entirely on the surface. Turning can expose fresh soil, break up some compacted surface layers, and make subsequent planting easier.
In heavy or wet soils, moldboard plowing can also create furrows that improve drainage. Historically, this was one reason it was so useful in northern Europe, where simple scratch plows were poorly suited to dense clay soils.
The coulter was also an addition to plows. It was a blade in front of the plowshare that made a narrow cut in the soil to reduce resistance for the rest of the plow.
Another improvement involved not the plow itself but its power source. Oxen are strong and relatively easy to feed, but they are slow.
During the Middle Ages, improvements in the horse collar and harness allowed horses to be used much more effectively for heavy draft work. Horses could generally work faster than oxen.
Combined with horseshoes and improved harness systems, horse-drawn plowing increased the amount of land that could be worked during the critical planting season.
This mattered because there is often only a limited window when soil moisture and weather are suitable for plowing and sowing. A farmer who could prepare more acreage during that window could cultivate a larger farm.
These developments led to the creation of the carruca, which was a heavy plow. What set the heavy plow apart from other plows was the addition of wheels.
This was a huge improvement because it allowed farmers to plow land that was previously difficult to plow. Much of northern France, Germany, the Low Countries, Britain, Poland, and Scandinavia contains heavy, wet clay soils.
Consequently, some historians have argued that the heavy plow contributed substantially to the economic and demographic expansion of medieval northern Europe.
Modern research has found a significant relationship between areas suited to heavy-plow cultivation and later medieval population growth and urbanization.
In effect, plow technology helped shift Europe’s agricultural center of gravity northward.
As plows got heavier, it often required more animals to pull them. Six or eight draft animals were not uncommon. While pulling a plow wasn’t a problem, turning a plow was a real headache. Farmers therefore preferred to make long passes before turning.
Fields consequently tended to be divided into long strips rather than small squares. This fit naturally into the medieval open-field system, where individual households cultivated strips on large communal fields.
Plowing technology therefore influenced not only agricultural productivity but also the physical landscape and social organization of medieval villages.
For centuries, plows were often built by local craftsmen. There was no standardized scientific design. The curvature of the moldboard depended largely upon experience and tradition.
During the 17th and 18th centuries, European farmers, engineers, and agricultural reformers increasingly tried to understand the plow’s geometry.
The goal was to create a moldboard that would turn soil smoothly while requiring as little pulling force as possible. This became particularly important during the British Agricultural Revolution.
One important advance was the Rotherham swing plow, developed in England in the early 18th century. Unlike many heavy wheeled plows, it was lighter and easier to handle.
Iron components increasingly replaced wood. This reduced the plow’s overall weight, meaning fewer animals could sometimes pull it.
This was significant economically because draft animals were expensive to maintain. A plow requiring two horses instead of four could dramatically reduce a farmer’s operating costs.
The Scottish inventor James Small made another important advance during the late 18th century. Rather than treating the moldboard as an arbitrary curved piece of material, Small experimented with its geometry.
By the 1770s, he had developed an improved iron swing plow whose shape allowed it to cut and turn soil with less resistance.
This was part of a broader trend taking place during the Agricultural Revolution. Farm machinery was increasingly being engineered rather than simply crafted.
Efficiency could be measured, draft resistance could be reduced, and parts could eventually be standardized.
One person fascinated by moldboard geometry was Thomas Jefferson. He attempted to mathematically calculate an ideal moldboard shape that would turn soil with minimal resistance.
Jefferson did not invent the moldboard plow, but his experiments illustrate how agricultural technology was increasingly being treated as an engineering problem during the Enlightenment.
The Industrial Revolution made another major improvement possible: cheap, standardized cast-iron plow components, rather than wrought iron.
English inventor Robert Ransome developed improved cast-iron plowshares during the late 18th century and later created hardened, self-sharpening designs.
Cast iron had several advantages. It could be poured into molds, which meant manufacturers could produce nearly identical parts in large numbers. Broken components could be replaced, rather than requiring an entire plow to be rebuilt by a local blacksmith.
A problem developed in the 19th century when homesteaders in the Great Plains tried to plow virgin prairie soil. Prairie soil was extraordinarily fertile, but it could be heavy and sticky.
Its thick network of grass roots created tough sod, and soil often clung to cast-iron moldboards. Farmers periodically had to stop and scrape the plow clean.
In 1837, Illinois blacksmith John Deere developed a commercially successful self-scouring steel plow designed for prairie conditions. The critical feature was a smooth, polished steel working surface. Instead of sticky prairie soil adhering to the moldboard, the soil slid across it, polishing the surface further.
It was the steel plow that opened up what would be the most productive agricultural land on Earth.
In this podcast, I’ve covered many inventions that have transformed human civilization. Take any one of them away, and the world would be a very different place.
Without question, one of the items we have to put into the Everything Everywhere Hall of Fame of things that made the world possible would be the humble plow.
It isn’t sexy, but we wouldn’t be here without it.