An efficient irrigation system should meet the demands of the growing crops. While limited water supply may result in yield reduction, excess irrigation is a waste of resources. To investigate water use efficiency, on-the-go sensing technology was used to reveal soil spatial variability relevant to water holding capacity (in this example, field elevation and apparent electrical conductivity). These high-density data layers were used to identify strategic sites where monitoring water availability during growing season allowed quantifying shortage and/or excess of water supply. Nine locations in a 37-ha agricultural field have been selected to monitor soil matrix potential and temperature at four depths (18, 48, 78, and 108 cm) using wireless technology. These locations represented different growing conditions. The measurements were used to quantify temporal variability of soil water content and water depletion, and then to assess whether optimization of irrigation water supply could increase water use efficiency as compared to the current uniform irrigation scheduling practice.