Knowledge of the quantity of water draining below the root-zone is necessary in order to maximise and ensure sustainable water use, particularly when surface water is applied for irrigated agricultural production. Traditionally, this has been based on soil hydraulic properties which whether measured directly or correlated with soil morphological properties, is difficult, time-consuming and expensive to determine (Shaw, 1988). Shaw and Thorbum (1985) indicated that soil leaching is closely related to hydraulic conductivity (K) and that important soil properties that influence K, including; clay content, clay mineralogy (cation exchange Capacity/Clay % Ratio, CCR) and exchangeable sodium percentage (ESP), can be used to predict Ieaching fraction (LF) and deep drainage (DD). As a consequence an empirical model was developed into a program called Sodium-SaLF, which provides estimates of LF, DD and average root zone EC, at steady-state, based on these laboratory measured soil properties that are generally collected during soil surveys (ie. CEC and clay content). A small number of water quality parameters, such as EC, , depth of irrigation water applied and annual rainfall, as well as the crop being grown is also required by the model. Estimating deep drainage on the field-scale is complicated because of the relatively large spatial variation of soil. Over the last decade clay content (Williams and Hoey, 1987); depth to clay (Doolittleet al, 1994) and Ieaching fraction (Slavich and Yang, 1987) have been estimated using Electromagnetic instruments. Here we demonstrate the use of a Mobile Electromagnetic Sensing System developed by Triantafilis and MCBratney (1998) and its potential in estimating deep drainage and average soil EC, at steady state using EC, data and soil information coupled to a salt and leaching fraction model or Sodium-SaLF (Shaw and Thorbum, 1995). The research was carried out in a irrigated cotton field in the lower Gwydir valley, Australia.