An agronomic field-scale sensor network for monitoring soil water and temperature variation

Monday, 15 December 2014
David J Brown, Washington State University, Crop and Soil Sciences, Pullman, WA, United States, Caley Gasch, Washington State University, Pullman, WA, United States, Erin S Brooks, University of Idaho, Moscow, ID, United States, David Rhys Huggins, USDA-ARS, Land Management and Water Conservation Research, Pullman, WA, United States, Colin S. Campbell, Decagon Devices, Pullman, WA, United States and Douglas R Cobos, Decagon Devices, Research and Development, Pullman, WA, United States
Environmental sensor networks have been deployed in a variety of contexts to monitor plant, air, water and soil properties. To date, there have been relatively few such networks deployed to monitor dynamic soil properties in cropped fields. Here we report on experience with a distributed soil sensor network that has been deployed for seven years in a research farm with ongoing agronomic field operations. The Washington State University R. J. Cook Agronomy Farm (CAF), Pullman, WA, USA has recently been designated a United States Department of Agriculture (USDA) Long-Term Agro-Ecosystem Research (LTAR) site. In 2007, 12 geo-referenced locations at CAF were instrumented, then in 2009 this network was expended to 42 locations distributed across the 37-ha farm. At each of this locations, Decagon 5TE probes (Decagon Devices Inc., Pullman, WA, USA) were installed at five depths (30, 60, 90, 120, and 150 cm), with temperature and volumetric soil moisture content recorded hourly. Initially, data loggers were wirelessly connected to a data station that could be accessed through a cell connection, but due to the logistics of agronomic field operations, we later buried the dataloggers at each site and now periodically download data via local radio transmission. In this presentation, we share our experience with the installation, maintenance, calibration and data processing associated with an agronomic soil monitoring network. We also present highlights of data derived from this network, including seasonal fluctuations of soil temperature and volumetric water content at each depth, and how these measurements are influenced by crop type, soil properties, landscape position, and precipitation events.