A Smart Sensor Array for Scheduling Precision Irrigation

To quantify the potential of precision irrigation, we began a research and demonstration project whose goal is to develop a soil moisture sensor-based variable rate irrigation (VRI) control system.  The control system consists of the University of Georgia Smart Sensor Array (UGA SSA) – a wireless soil moisture sensing system with a high density of sensor nodes, a VRI enabled center pivot irrigation system, and a web-based user interface.  The operational paradigm is that the field is divided into irrigation management zones.  The UGA SSA monitors soil condition within the zones and provides hourly soil moisture measurements to the web-based user interface.  At the interface, the soil moisture data are used by an irrigation scheduling model running in the background to develop irrigation scheduling recommendations by zone.  The recommendations are then approved by the user (farmer) and downloaded to the VRI controller on the center pivot as a precision irrigation prescription.  When the center pivot irrigation system is engaged by the farmer, the pivot applies the recommended rates. 

The project began during the spring of 2012.  The UGA SSA was deployed in eight of ten demonstration fields with a minimum of ten sensor nodes per field.  Field size averaged 80 ha.  The eight instrumented fields were planted to cotton or peanut.  Soil moisture data were collected hourly by the UGA SSA for the entire growing season and streamed to a web server where they were displayed.  All ten center pivot irrigation systems in the demonstration fields were equipped with VRI controls.  Full precision irrigation will be implemented during the 2013 growing season using the paradigm described above. This paper will describe our system in detail providing data from the components which have been completed and are operational.