An agricultural row unit includes an attachment frame adapted to be rigidly connected to a towing frame, and a linkage assembly pivotably coupled to the attachment frame to permit vertical pivoting movement of the linkage assembly relative to the attachment frame. A hydraulic cylinder is coupled to the linkage assembly for urging the linkage assembly downwardly toward the soil, and an accumulator is mounted to the hydraulic cylinder for supplying pressurized gas to the hydraulic cylinder urging the linkage assembly upwardly away from the soil. A manifold is removably mounted to the hydraulic cylinder via a mounting interface, the manifold being selected from a group of different types of modular manifolds in which each manifold is removably mountable to the hydraulic cylinder, one at a time, via the same mounting interface, the manifold having two hydraulic-fluid ports including an inlet port and an outlet port.