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Improved designs

The basic plough with coulter, ploughshare and mould board remained in use for a millennium. Major changes in design spread widely in the Age of Enlightenment, when there was rapid progress in design. Joseph Foljambe in Rotherham, England, in 1730, used new shapes based on the Rotherham plough, which covered the mould board with iron. Unlike the heavy plough, the Rotherham, or Rotherham swing plough consisted entirely of the coulter, mould board and handles. It was much lighter than earlier designs and became common in England. It may have been the first plough widely built in factories and commercially successful there.

In 1789 Robert Ransome, an iron founder in Ipswich, started casting ploughshares in a disused malting at St Margaret's Ditches. A broken mould in his foundry caused molten metal to come into contact with cold metal, making the metal surface extremely hard. This process, chilled casting, resulted in what Ransome advertised as "self-sharpening" ploughs. He received patents for his discovery.

James Small further advanced the design. Using mathematical methods, he eventually arrived at a shape cast from a single piece of iron, an improvement on the Scots plough of James Anderson of Hermiston. 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 1833 John Lane invented a steel plough. Then in 1837 John Deere introduced a steel plough; it was so much stronger than iron designs that it could work soil in US areas previously thought unsuitable for farming.

Improvements on this followed developments in metallurgy: steel coulters and shares with softer iron mould boards to prevent breakage, the chilled plough (an early example of surface-hardened steel), and eventually mould boards with faces strong enough to dispense with the coulter.

By the time of the early 1900s, the steel plough had many uses, shapes and names. The "two horse breaking plough" had a point and wing used to break the soil's surface and turn the dirt out and over. The "shovel plough" was used to lay off the rows. The "harrow plough" was used to cover the planted seed. The "scratcher" or "geewhiz" was used to deweed or cultivate the crop. The "bulltongue" and "sweeps" were used to plough the middle of the rows. All these metal plough points required being re-sharpened about every ten days, due to their use on rough and rocky ground.