AÃÂ disc harrowÃÂ is a farm implement that is used to till the soil whereÃÂ cropsÃÂ are to be planted. It is also used to chop up unwanted weeds orÃÂ cropremainders. ... The concavity of thediscsÃÂ as well as their offset angle causes them to loosen and lift the soil that they cut.