Harrow (tool)

The purpose of harrowing is to break up clods and to provide a soil structure, called tilth, that is suitable for planting seeds.

Harrows differ from ploughs, which cut the upper 12 to 25 centimetre (5 to 10 in) layer of soil, and leave furrows, parallel trenches.

Harrows were originally drawn by draft animals, such as horses, mules, or oxen, or in some times and places by manual labourers.

Tine harrows are used to refine seed-bed conditions before planting, remove small weeds in growing crops, and loosen the inter-row soils to allow water to soak into the subsoil.

Similarly, in sports-ground maintenance, light chain harrowing is often used to level off the ground after heavy use to remove and smooth out boot marks and indentations.

Used on tilled land in combination with the other two types, chain harrowing rolls remaining larger soil clumps to the surface, where weather breaks them down and prevents interference with seed germination.

Giant scalloped-edged discs operate in a set, or frame, that is often weighted with concrete or steel blocks to improve penetration of the cutting edges.

An Arabic reference to harrows is to be found in Abu Bakr Ibn Wahshiyya's Nabatean Agriculture (Kitab al-Filaha al-Nabatiyya), of the 10th century, but claiming knowledge from Babylonian sources.