Typically, it will be attached to the tractor via the three-point hitch or draw bar. The planter is designed not only to take the effort out of sowing the crop, but also to introduce a greater degree of accuracy into the planting process. This is achieved by the even spacing of the planter row units and the steady speed of the tractor during planting.
Planters can vary extensively in size and capacity, from small single-row planters to large multi-row units such as the 48-row John Deere DB 120. Different planting patterns can also be achieved to suit different crops, simply by adjusting the row unit spacing. Some planters also feature an arm which extends a set length from the side of the machine to create a small furrow in the field to guide the tractor on its next pass. This guiding system can simply be a single harrow attached to an extending arm on either side of the planter unit.
While this is a common and simple approach on smaller or older planters, the more modern and larger units resort to technology to achieve the same goal. They will typically utilise GPS systems and the tractor\'s auto-steer functionality.
There are also computer-control systems for planters that can sow seeds in a precise pattern to an accuracy of just two centimetres. Such systems can also remember where they have already planted, so they will not sow the seed when the tractor retraces its steps in order to access areas in an irregular-shaped field.
A standard planter may have a seed bin for each row and also a fertiliser bin on board. Toothed plates are installed in each bin to suit a particular seed type. The technology is mature and fairly sturdy, and a used planter could easily give many years of trouble-free service.