Disc harrow

A disc harrow is a farm implement that is used to till the soil where crops are to be planted. It is also used to chop up unwanted weeds or crop remainders. It consists of many carbon steel and sometimes the longer lasting boron discs, which have many varying concavities and disc blade sizes and spacing (the choices of the later being determined by the final result required in a given soil type) and which are arranged into two sections ("offset disc harrow") or four sections ("tandem disc harrow"). When viewed from above, the four sections would appear to form an "X" which has been flattened to be wider than it is tall. The discs are also offset so that they are not parallel with the overall direction of the implement. This arrangement ensures that the discs will repeatedly slice any ground to which they are applied, in order to optimize the result. The concavity of the discs as well as their offset angle causes them to loosen and lift the soil that they cut.

Name variations

In various regions of the United States, farmers call these implements just discs (or disks), and they reserve the word harrow for the lighter types of harrow, such as chain and tooth harrows. Therefore, in these regions, the phrase "plowing, disking, and harrowing" refers to three separate tillage steps. This is not any official distinction but is how farmers tend to speak.