Life Under Your Feet: An End-to-End Soil Ecology Sensor Network, Database, Web Server, and Analysis Service

Wireless sensor networks can revolutionize soil ecology by providing measurements at temporal and spatial granularities previously impossible. This paper presents a soil monitoring system we developed and deployed at an urban forest in Baltimore as a first step towards realizing this vision. Motes in this network measure and save soil moisture and temperature in situ every minute. Raw measurements are periodically retrieved by a sensor gateway and stored in a central database where calibrated versions are derived and stored. The measurement database is published through Web Services interfaces. In addition, analysis tools let scientists analyze current and historical data and help manage the sensor network. The article describes the system design, what we learned from the deployment, and initial results obtained from the sensors. The system measures soil factors with unprecedented temporal precision. However, the deployment required device-level programming, sensor calibration across space and time, and cross-referencing measurements with external sources. The database, web server, and data analysis design required considerable innovation and expertise. So, the ratio of computer-scientists to ecologists was 3:1. Before sensor networks can fulfill their potential as instruments that can be easily deployed by scientists, these technical problems must be addressed so that the ratio is one nerd per ten ecologists.