A plough (UK) or plow (US; both /plaʊ/) is a tool or farm implement used for initial cultivation to loosen or turn the soil in preparation for sowing seed or planting. Ploughs were traditionally drawn by working animals such as oxen and horses, but in modern farms are drawn by tractors. A plough may be made of wood, iron, or steel frame with an attached blade or stick used to cut and loosen the soil. It has been a basic instrument for most of history, and is one of the most significant inventions. The earliest ploughs were wheelless, with the Romans using a wheelless plough called the aratrum, but Celtic peoples began using wheeled ploughs during the Roman era.
The primary purpose of ploughing is to turn over the upper layer of the soil, bringing fresh nutrients to the surface, while burying weeds and the remains of previous crops and allowing them to decay. As the plough is drawn through the soil, it creates long trenches of fertile soil called furrows. In modern use, a ploughed field is typically left to dry out, and is then harrowed before planting. Ploughing and cultivating a soil homogenises and modifies the upper 12 to 25 centimetres (5 to 10 in) to form a plough layer, where the majority of fine plant feeder roots grow.
Ploughs were initially human-powered, but the process became considerably more efficient once animals were pressed into service. The first animal-powered ploughs were undoubtedly pulled by oxen, and later in many areas by horses and mules, although various other animals have been used for this purpose. The industrial revolution brought steam engines to pull ploughs, ploughing engines or steam tractors, which were gradually superseded by internal-combustion-powered tractors.
Modern competitions take place for ploughing enthusiasts like the National Ploughing Championships in Ireland. Use of the plough has decreased in some areas, often those significantly threatened by soil damage and erosion, in favour of shallower ploughing and other less-invasive conservation tillage techniques.
ARTICLES SOURCES : https://en.wikipedia.org/wiki/Plough