US Patent 10182522 Depth control of an agricultural fertilizer row unit

A fertilizer row unit including a toolbar coupling, first and second suspension members, a pressure applying device, a tensioned wheel assembly, a knife assembly and a depth control system. The first suspension member has a first end pivotally coupled to the toolbar coupling. The second suspension member is generally parallel to the first suspension member. The pressure applying device is coupled to the first or second suspension member. The tensioned wheel assembly has at least one wheel. The knife assembly is pivotally coupled to both the first and second suspension members. The depth control system is coupled to the knife assembly for controlling the depth of penetration of the knife into the soil. The depth control system includes a sensor that provides a measured depth signal representative of a depth of the knife. The depth control system controls the pressure applying device dependent upon the measured depth signal.