Definition: On a farm, a tractor can be used by someone with a plough, or animals are used to pull a plough to make furrows and turn over the soil. This is to break up the hard crust of the soil, ready for sowing. On the top of the soil, there may be dead crops from the previous harvest. These are broken up and mixed up with the soil during ploughing, as well as bringing up a fresh layer of soil with good nutrients to the top, ready for planting new crops.