Soil moisture is critical to crops on the prairies, however, observations are available at a range of different scales. Point scale observations are simple, but may have limited value in representing conditions over the field. Large scale estimates can be obtained from remote sensing and models, but these also may not resolve conditions in a particular field. Field scale observations are possible using various methods, including geological weighing lysimeters. Sub-field scale estimates provide the most precise and useful information, and are needed for precision agriculture, but remain challenging. In this study we examine the performance of a geological weighing lysimeter installed at Duck Lake, Saskatchewan. We use a range of observations and models to critically assess the performance of this field scale estimate of soil moisture. We show that to explain nuanced differences between point scale measurements, field scale measurements, and model outputs, it is necessary to account for the heterogeneous infiltration, evapotranspiration and groundwater drainage fluxes that occur at sub-field scale. Where favourable conditions exist, geological weighing lysimeters can be a useful tool to track long term, high frequency (hourly) changes in field scale soil moisture.