A row-crop tractor is a tractor tailored specifically to the growing of row crops (crops grown in rows, as in truck farming), and most especially to cultivating. Cultivating can take place anytime from soon after the crop plants have sprouted until soon before they are harvested. Several rounds of cultivating may be done over the season. A row-crop tractor essentially brings together a farm tractor and its cultivator into one machine, in the same way that motive power has been combined into other machinery (for example, horseless carriages combined the motive power into transport vehicles; self-propelled guns combined the artillery tractor and its gun into one machine).