The disclosure herein describes a control device for use with an underground drainage and irrigation network formed of a main conduit line and of adjacently disposed water permeable secondary conduit lines. At least one head control stand is used defining a water-collecting chamber with a pair of float members therein. These floats are operatively connected to respective drainage and irrigation control valves. The chamber communicates with an underground duct having a free, perforated end positioned between a pair of secondary lines to collect underground water received in the chamber to influence the floats. The valves are operated by the floats to maintain an underground water table between the two adjacent secondary lines at a level adequate for optimal plant growth.