Disc harrow is used to till the soil where crops are to be planted. It is also used to chop up unwanted weeds or crop remainders. 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.