Ground-penetrating radar (GPR) is used to measure the volumetric soil water content (theta(V)) on large-field scales. The improved technique we use has been shown to be more effective than conventional GPR techniques. GPR has advantages over other methods (i.e. gravimetric method by oven drying, time domain reflectometry) because the antennae are lying on the ground surface and does not have to be inserted into the subsurface. Therefore, water content can rapidly be determined down to a depth of approximately Im by a high spatial resolution of a few meters.