Disclosed are methods and apparatus for blending wastewater with fresh water for fertigation of a crop. In one embodiment, the wastewater and the fresh water are blended at a predetermined flow ratio through a blending valve to obtain a blended stream. A logic based controller controls the blending valve to set a predetermined flow ratio according to the electricity conductivity (EC) of the blended water stream. The blending, measuring, and adjusting steps form a feedback loop so as to maintain the blended stream at a target EC value.
