Hoeing
When agriculture was first developed, simple hand-held digging sticks or hoes would have been used in highly fertile areas, such as the banks of the Nile where the annual flood rejuvenates the soil, to create furrows wherein seeds could be sown. To grow crops regularly in less fertile areas, the soil must be turned to bring nutrients to the surface.
Scratch plough
The domestication of oxen in Mesopotamia and by its contemporary Indus valley civilization, perhaps as early as the 6th millennium BC, provided mankind with the pulling power necessary to develop the plough. The very earliest plough was the simple scratch-plough, or ard, which consists of a frame holding a vertical wooden stick that was dragged through the topsoil, it is still used in many parts of the world. It breaks up a strip of land directly along the ploughed path, which can then be planted. Because this form of plough leaves a strip of undisturbed earth between the rows, fields are often cross-ploughed at 90 degree angles, and this tends to lead to squarish fields. In the archaeology of northern Europe, such squarish fields are referred to as “Celtic fields”.
Crooked ploughs
The Greeks apparently introduced the next major advance in plough design; the crooked plough, which angled the cutting surface forward, leading to the name. The cutting surface was often faced with bronze or (later) iron. Metal was expensive, so in times of war it was melted down or forged to make weapons—or the reverse in more peaceful times. This is presumably the origin of the expression found in the Bible “beat your swords to ploughshares”.
Mouldboard plough
A major advance in plough design was the mouldboard plough, which aided the cutting blade. The coulter, knife or skeith cuts vertically into the ground just ahead of the share (or frog) a wedge-shaped surface to the front and bottom of the mouldboard with the landside of the frame supporting the below-ground components. The upper parts of the frame carry (from the front) the coupling for the motive power (horses), the coulter and the landside frame. Depending on the size of the implement, and the number of furrows it is designed to plough at one time, there is a wheel or wheels positioned to support the frame. In the case of a single-furrow plough there is only one wheel at the front and handles at the rear for the ploughman to steer and manoeuvre it.
An advance on the basic design was the iron ploughshare, a replaceable horizontal cutting surface mounted on the tip of the share. The earliest ploughs with a detachable and replaceable share date from around 1000 BC in the Ancient Near East, and the earliest iron ploughshares from ca. 500 BC in China. Early mouldboards were basically wedges that sat inside the cut formed by the coulter, turning over the soil to the side. The ploughshare spread the cut horizontally below the surface, so when the mouldboard lifted it, a wider area of soil was turned over. Mouldboards are known in Britain from the late 6th century on.
Loy ploughing
Loy ploughing was a form of manual ploughing which took place in Ireland on very small farms or on very hilly ground, where horses could not work or where farmers could not afford them. It was used up until the 1960s in poorer land. This suited the moist climate of Ireland as the trenches formed by turning in the sods providing drainage. It also allowed the growing of potatoes in bogs as well as on mountain slopes where no other cultivation could take place.
Heavy ploughs
In the basic mouldboard plough the depth of the cut is adjusted by lifting against the runner in the furrow, which limited the weight of the plough to what the ploughman could easily lift. This limited the construction to a small amount of wood (although metal edges were possible). These ploughs were fairly fragile, and were not suitable for breaking up the heavier soils of northern Europe. The introduction of wheels to replace the runner allowed the weight of the plough to increase, and in turn allowed the use of a much larger mouldboard faced in metal. These heavy ploughs led to greater food production and eventually a significant population increase around 600 AD.
Before the Han Dynasty (202 BC–220 AD), Chinese ploughs were made almost entirely of wood, spare the iron blade of the ploughshare. By the Han period, the entire ploughshare was made of cast iron; these are the first known heavy moldboard iron ploughs.
The Romans achieved the heavy wheeled mouldboard plough in the late 3rd and 4th century AD, when archaeological evidence appears, inter alia, in Roman Britain. The first indisputable appearance after the Roman period is from 643, in a northern Italian document. Old words connected with the heavy plough and its use appear in Slavic, suggesting possible early use in this region. The general adoption of the mouldboard plough in Europe appears to have accompanied the adoption of the three-field system in the later eighth and early ninth centuries, leading to an improvement of the agricultural productivity per unit of land in northern Europe.
Research by the French historian Marc Bloch in medieval French agricultural history showed the existence of names for two different ploughs, “the araire was wheel-less and had to be dragged across the fields, while the charrue was mounted on wheels”.
Improved designs
The basic plough with coulter, ploughshare and mouldboard remained in use for a millennium. Major changes in design did not become common until the Age of Enlightenment, when there was rapid progress in design. Joseph Foljambe in Rotherham, England, in 1730 used new shapes as the basis for the Rotherham plough, which also covered the mouldboard with iron. Unlike the heavy plough, the Rotherham (or Rotherham swing) plough consisted entirely of the coulter, mouldboard and handles. It was much lighter than conventional designs and became very popular in England. It may have been the first plough to be widely built in factories.
James Small further improved the design. Using mathematical methods he experimented with various designs until he arrived at a shape cast from a single piece of iron, the Scots plough. A single-piece cast iron plough was also developed and patented by Charles Newbold in the United States. This was again improved on by Jethro Wood, a blacksmith of Scipio, New York, who made a three-part Scots Plough that allowed a broken piece to be replaced. In 1837 John Deere introduced the first steel plough; it was so much stronger than iron designs that it was able to work the soil in areas of the US that had previously been considered unsuitable for farming. Improvements on this followed developments in metallurgy; steel coulters and shares with softer iron mouldboards to prevent breakage, the chilled plough which is an early example of surface-hardened steel, and eventually the face of the mouldboard grew strong enough to dispense with the coulter.
Single-sided ploughing
The first mouldboard ploughs could only turn the soil over in one direction (conventionally always to the right), as dictated by the shape of the mouldboard, and so the field had to be ploughed in long strips, or lands. The plough was usually worked clockwise around each land, ploughing the long sides and being dragged across the short sides without ploughing. The length of the strip was limited by the distance oxen (or later horses) could comfortably work without a rest, and their width by the distance the plough could conveniently be dragged. These distances determined the traditional size of the strips: a furlong, (or “furrow’s length”, 220 yards (200 m)) by a chain (22 yards (20 m))—an area of one acre (about 0.4 hectares); this is the origin of the acre. The one-sided action gradually moved soil from the sides to the centre line of the strip. If the strip was in the same place each year, the soil built up into a ridge, creating the ridge and furrow topography still seen in some ancient fields.
Turnwrest plough
The turnwrest plough allows ploughing to be done to either side. The mouldboard is removable, turning to the right for one furrow, then being moved to the other side of the plough to turn to the left (the coulter and ploughshare are fixed). In this way adjacent furrows can be ploughed in opposite directions, allowing ploughing to proceed continuously along the field and thus avoiding the ridge and furrow topography.
Reversible plough
The reversible plough has two mouldboard ploughs mounted back-to-back, one turning to the right, the other to the left. While one is working the land, the other is carried upside-down in the air. At the end of each row, the paired ploughs are turned over, so the other can be used. This returns along the next furrow, again working the field in a consistent direction.
Riding and multiple-furrow ploughs
Early steel ploughs, like those for thousands of years prior, were walking ploughs, directed by the ploughman holding onto handles on either side of the plough. The steel ploughs were so much easier to draw through the soil that the constant adjustments of the blade to react to roots or clods was no longer necessary, as the plough could easily cut through them. Consequently it was not long after that the first riding ploughs appeared. On these, wheels kept the plough at an adjustable level above the ground, while the ploughman sat on a seat where he would have earlier walked. Direction was now controlled mostly through the draught team, with levers allowing fine adjustments. This led very quickly to riding ploughs with multiple mouldboards, dramatically increasing ploughing performance.
A single draught horse can normally pull a single-furrow plough in clean light soil, but in heavier soils two horses are needed, one walking on the land and one in the furrow. For ploughs with two or more furrows more than two horses are needed and, usually, one or more horses have to walk on the loose ploughed sod—and that makes hard going for them, and the horse treads the newly ploughed land down. It is usual to rest such horses every half hour for about ten minutes.
Heavy volcanic loam soils, such as are found in New Zealand, require the use of four heavy draught horses to pull a double-furrow plough. Where paddocks are more square than long-rectangular it is more economical to have horses four wide in harness than two-by-two ahead, thus one horse is always on the ploughed land (the sod). The limits of strength and endurance of horses made greater than two-furrow ploughs uneconomic to use on one farm.
Amish farmers tend to use a team of about seven horses or mules when spring ploughing and as Amish farmers often help each other plough, teams are sometimes changed at noon. Using this method about 10 acres can be ploughed per day in light soils and about 2 acres in heavy soils.
Steam ploughing
The advent of the mobile steam engine allowed steam power to be applied to ploughing from about 1850. In Europe, soil conditions were often too soft to support the weight of heavy traction engines. Instead, counterbalanced, wheeled ploughs, known as balance ploughs, were drawn by cables across the fields by pairs of ploughing engines which worked along opposite field edges. The balance plough had two sets of ploughs facing each other, arranged so when one was in the ground, the other set was lifted into the air. When pulled in one direction the trailing ploughs were lowered onto the ground by the tension on the cable. When the plough reached the edge of the field, the opposite cable was pulled by the other engine, and the plough tilted (balanced), putting the other set of shares into the ground, and the plough worked back across the field.
One set of ploughs was right-handed, and the other left-handed, allowing continuous ploughing along the field, as with the turnwrest and reversible ploughs. The man credited with the invention of the ploughing engine and the associated balance plough, in the mid nineteenth century, was John Fowler, an English agricultural engineer and inventor.
In America the firm soil of the Plains allowed direct pulling with steam tractors, such as the big Case, Reeves or Sawyer Massey breaking engines. Gang ploughs of up to fourteen bottoms were used. Often these big ploughs were used in regiments of engines, so that in a single field there might be ten steam tractors each drawing a plough. In this way hundreds of acres could be turned over in a day. Only steam engines had the power to draw the big units. When internal combustion engines appeared, they had neither the strength nor the ruggedness compared to the big steam tractors. Only by reducing the number of shares could the work be completed.
Stump-jump plough
The Stump-jump plough was an Australian invention of the 1870s, designed to cope with the breaking up of new farming land, that contains many tree stumps and rocks that would be very expensive to remove. The plough uses a moveable weight to hold the ploughshare in position. When a tree stump or other obstruction such as a rock is encountered, the ploughshare is thrown upwards, clear of the obstacle, to avoid breaking the plough’s harness or linkage; ploughing can be continued when the weight is returned to the earth after the obstacle is passed.
A simpler system, developed later, uses a concave disc (or a pair of them) set at a large angle to the direction of progress, that uses the concave shape to hold the disc into the soil—unless something hard strikes the circumference of the disk, causing it to roll up and over the obstruction. As the arrangement is dragged forward, the sharp edge of the disc cuts the soil, and the concave surface of the rotating disc lifts and throws the soil to the side. It doesn’t make as good a job as the mouldboard plough (but this is not considered a disadvantage, because it helps fight the wind erosion), but it does lift and break up the soil (see disc harrow).
Modern ploughs
Modern ploughs are usually multiple reversible ploughs, mounted on a tractor via a three-point linkage. These commonly have between two and as many as seven mouldboards—and semi-mounted ploughs (the lifting of which is supplemented by a wheel about half-way along their length) can have as many as eighteen mouldboards. The hydraulic system of the tractor is used to lift and reverse the implement, as well as to adjust furrow width and depth. The ploughman still has to set the draughting linkage from the tractor so that the plough is carried at the proper angle in the soil. This angle and depth can be controlled automatically by modern tractors. As a complement to the rear plough a two or three mouldboards-plough can be mounted on the front of the tractor if it is equipped with front three-point linkage.
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