One of the key challenges for AfSIS is how to measure soil functional properties on tens of thousands of georeferenced soil samples. Spectral diagnostics – the use of low cost, high throughput analytical techniques based on light reflectance – solves this problem. Infrared and x-ray spectroscopic analytical techniques that required minimal sample preparation are used as a front line screening tool. More expensive and time-consuming measurements of soil functional properties are then calibrated to the spectral measurements on a subset of samples.