A hydraulic system is provided for an air cart towed by a tow vehicle across a field. The hydraulic system includes a first selector valve configured to selectively communicate a first flow rate regulated by a first control valve to drive a hydraulic-driven auger mechanism at the air cart. The hydraulic system also includes a second selector valve control configured to selectively communicate a second flow rate regulated by a second control valve to drive a hydraulic-driven pressure source at the air cart. The first and second selector valves and first and second control valves are located at the tow vehicle, and are connected via a common hydraulic line to a main selector valve located at the air cart. The main selector valve is connected to selectively communicate the first hydraulic fluid flow rate to a pressure source and the second hydraulic fluid flow rate to the hydraulic-driven auger mechanism.