The 5tm moisture sensor (Meter Group) is an accurate method for collecting data. Unfortunately, collecting data from multiple locations requires long runs of wire between the sensor and the data logger. These wires are a point of vulnerability the system, rodents chew any exposed cable and wild horses and cows unplug the sensors by tripping over the wires.
To solve this, data are collected and sent using an arduino pro mini attached to an NRF24L radio. This design is for the sensor end of the setup.