National Program for Sustainable Irrigation Fact sheet 2005/1 Australian studies show an average of 30% of applied irrigation water passes through the root zone without being used by the crops it is intended to sustain. This water either becomes groundwater recharge or is intercepted by drainage networks and contributes to waterway pollution. Subsurface drip irrigation has shown great potential for increasing crop yield and uniformity, while decreasing water use and environmental impact. Importantly, subsurface irrigation applies water directly to the