Long-Range Bluetooth Smart Stake System for Soil Sensing

Precision agriculture depends on accurate spatial soil information to efficiently deploy resources. While remote sensing can provide high coverage, some soil properties must be measured in situ. The design of a low-power, long-range system for soil surveillance is outlined. Sensor nodes consist of battery-powered transmitters with temperature sensors at various soil depths. Nodes measure temperatures and broadcast data intermittently using Bluetooth long-range protocols and unacknowledged advertisements. A high-gain antenna connected to a receiver captures broadcasts from nodes. A prototype system was deployed outdoors for several weeks. Received data from transmitter nodes were used to reconstruct soil thermal histories at each node location. Good correlation with local weather data validates the data captured by the system.