The goal of accurately mapping soil variability preceded GPS-aided agriculture, and has been a challenging aspect of precision agriculture since its inception.  Many studies have found the range of spatial dependence is shorter than the distances used in most grid sampling.  Other studies have examined variability within government soil surveys and concluded that they have limited utility in many precision applications.  Proximal soil sensing has long been envisioned as a method that would provide the full field coverage needed to accurately delineate soil productivity zones.  Of the various sensing technologies, soil electrical conductivity (EC) sensing has seen the most widespread use, and adoption is increasing.  The soil EC signal responds primarily to soil texture changes and in cases where salinity levels are elevated, it delineates those areas as well.  While soil texture is an important factor in crop production, there are other factors to consider including organic matter, soil pH, and landscape position.  A new suite of soil sensors that simultaneously measures these properties has been commercialized by Veris Technologies.   To evaluate the accuracy of the sensors, a  multi-state, multi-field study was conducted, and sensor readings were validated with lab-analyzed soil samples.  Results show strong correlation between sensors and lab data, and overlaying sensor maps with soil surveys and 1 ha grid cells confirms the need for detailed soil mapping.