Coulter (agriculture)

A simple drawn plough: 4) marks the coulter (using an early knife-like design)

A coulter or colter is a vertically mounted component of many plows that cuts an edge about 7 inches (18 cm) deep ahead of a plowshare.^[1] Its most effective depth is determined by soil conditions.^[2]

History

Its earliest design consisted of a knife-like blade.^[3][1] Coulters with a flat rotating disc began being used c. 1900.^[4][1] Its advantage was a smoothly cut bank, and it sliced plant debris to the width of the furrow.^[2]

Results

In his 1844 book, Henry Stephens used dynamometer measurements to conclude that a plow without a coulter took about the same amount of force to pull but using a coulter resulted in a much cleaner result.^[1] It softens the soil, allowing the plow to undercut the furrow made by the coulter.^[1]

Jointer

Coulter (center) and Jointer (left)

A rolling coulter has an optional accessory called a "jointer".^[2] The jointer flips over a small part of the surface on top of the slice before the plowshare flips the main slice.^[2] It ensures that all of the plant debris gets covered by the flipped slice.^[2]

References