In a system for treating soil and turf by blowing and/or vacuuming through a duct network located underneath the turf, a low-pressure high-volume fan is typically used to move air into the soil profile or suck moisture out of the soil profile. U.S. Pat. Nos. 5,433,759; 5,507,595; 5,542,208; 5,617,670; 5,596,836; and 5,636,473 show different variations on equipment used for this purpose. Since a non-reversing fan always rotates in the same direction, changing the system from a blowing function to a vacuuming function requires disconnecting the duct network from the blowing outlet of the fan unit and connecting it to the vacuum inlet of the unit. In some variations, a 4-way valve is used to avoid the hassles involved with selectively connecting and disconnecting the duct network from the various ports of the fan unit.