The main aim of this research was to refine best management practices for dryland lucerne (Medicago sativa L.) crops in relation to crop water extraction. To do this, dryland lucerne was established at Lincoln University, New Zealand in two soils which differed in the plant available water content (PAWC). The low PAWC site (Ashely Dene) had a very stony silt loam soil with ~130 mm of water to 2.3 m. The high PAWC site (Iversen 12) is a deep silt loam soil with ~360 mm of water to 2.3 m. The available water for crop extraction in the establishment year was manipulated by imposing the second treatment, sowing date. This resulted in mean annual dry matter (DM) yields which ranged from 0.4 to 21.5 t DM/ha. A detailed examination of lucerne physiology was undertaken to determine how lucerne extracts water from the soil to explain these yield differences.