Automated collection of soil-moisture data with a low-cost microcontroller circuit

Monitoring the moisture status of the soil profile is one method used to schedule irrigations. Manual collection of moisture-sensor data, however, can be labor- and time-intensive and cost prohibitive. Automating the data-collection process allows information to be collected at high frequency with less labor requirements. Reducing the cost of automated measurement equipment would allow more locations to be monitored cost effectively. A low-cost, microcontroller-based datalogger circuit board was designed to continuously monitor and record moisture-sensor data. Circuit boards were fabricated by hand at a cost of $20 in materials, and required 3 h of labor to construct. During two growing seasons, 150 dataloggers were deployed for use in scheduling irrigations. The design, components, programming, operation, and performance of the circuit are described in this article.