The UC Merced testbed consists of two sites: The first site is an 8 acre pistachio orchard located south of Merced, California with 8 years old trees. The second site is a private 22-acre almond orchard at North West of Stevinson, California. This site includes 5 years old trees with some variability in soil type.
At this testbed, IoT4Ag researchers have designed and fabricated several sap-flow and trunk moisture sensors, light sensors, and low-power weather stations and developed software and hardware for Wi-Fi towers and data storage servers. However, these two tree crop sites have limited or no internet coverage, representing a realistic scenario and challenge for deploying IoT technologies in agricultural environments. Internet coverage at the pistachio site has been expanded by installing three Wi-Fi range extender towers in different places in the field and setting up a data server to collect sensor data from the field. In the Almond orchard where there is no internet coverage, a local data storage server has been specifically designed for this field and a battery-powered weather station that measures the ambient temperature, humidity, and barometric pressure was installed. As the trees get larger, they will become significant obstacles to the continuous connectivity of wireless systems and diminish the reliability, effectiveness, and range of the previously installed wireless systems in the field. Therefore, IoT4Ag plans to update and upgrade the wireless network based on the annual tree size changes in the testbed.