Soil column to demonstrate soil-water movement

There is a continuing need to demonstrate soil-water movement concepts in a laboratory/classroom setting. A soil column system is presented that provides students and teachers with a resource to identify and understand the complex relationships between key soil variables such as soil textural class, water potential, and water content. The column is instrumented with tensiometers (pressure transducers in porous plate housings) to measure pressure and matric water potential and with time domain reflectometry (TDR) probes to measure water content. Solenoid valves control the filling and draining of water to and from the column. All control and data collection tasks can potentially be overseen by a single datalogger. Water potential and water content can be varied hy raising and lowering the water table in the column. Basic soil physics concepts can be demonstrated, as well as more complex behavior such as hysteresis. Various soil types and profile configurations can also be investigated. The column proved useful and instructive once complete and functioned without incident.