A system processes images of soil using image processing techniques that help to reveal soil characteristics and differences between soil characteristics. The characteristics may be indicative of soil type, and the differences between soil characteristics help to identify where soil types change in a field. The system may determine management zones for a field based on the soil characteristics, e.g., by identifying multiple regions within a field, each management zone corresponding to similar soil characteristics. The system may communicate the management zones to devices in the field, to land appraisers, or to customers who use the results to manage the soil, as just a few examples.