For the asterism known as "The Plough"...see: Ursa Major.
Ploughing has several beneficial effects. The major reason for ploughing is to incorporate the residue from the previous crop into the soil. Ploughing also reduces the prevalence of weeds in the fields, and makes the soil more porous, easing later planting.
The early German word before sound-shift is plug and in Old Prussian plugis. After the German sound shift (p = pf) it became the modern German word Pflug.
The early scratch-ploughs were simple forked branches and the plugis, recorded in Elbing, Warmia had to be used twice, once horizontal, then vertical. Later developed mouldboard ploughs (American spelling: moldboard) turned the soil in one run across the field, depositing the weeds and undecomposed remains of the previous crop under the soil, and raising the rain-percolated nutrients to the surface. This plough also allowed ploughing while the ground was wet. The water was drained due to channels formed under the overturned earth. It also had a coulter, which was a blade attatched to the leading edge of the plough to cut through the sod and which would cut deepset and tough roots. Since the mouldboard plough was harder to turn around than the scratch plough, its inception brought about a change in the shape of fields from mostly square fields into longer rectangular "strips".
The first commercially successful iron plough was the Rotherham plough, developed by Joseph Foljambe in Rotherham, England, in 1730. It was durable and light, and was engineered after the mathematical principles of James Small, who designed a mouldboard that would cut, lift and fully turn over the earth.
Steel ploughs were developed during the industrial revolution, and were lighter and more durable than ploughs made of iron or wood. The first of these were walking ploughs, having two handles held by the operator to provide a degree of control over the depth and location of the furrow. Riding ploughs with wheels and a seat for the operator came later, and often had more than one share.
Ploughs are assumed to be of non-Indo-European origin, as shown in early documents from the Middle-East. Stone-age petroglyphs show ploughs and oxen being used in the Alpine countries and Egyptian paintings of ploughs occur in farming scenes.
Frame
Frog
Share or Mouldboard
Landside
Handles
Hitch
Doubletree
Knife
On modern ploughs and some older ploughs, the mouldboard is separate from the shin and bottom, allowing these parts to be replaced without replacing the mouldboard. Abrasion eventually destroys all parts of a plough that contact the soil.
See also: Aratrum (Ancient Greek plough), Ploughman's lunchPlough Parts