Ann industrial grade soil sensor to get moisture and temperature at two deep levels using two ComWin Top professional soil sensors and a ESP8266 development board (Wemos D1 mini Pro v2) battery powered with a solar panel support. The code reads the sensor values and publish them to a MQTT broker.
This is the "schematics"
And this is a moisture graph made with Grafana from the sensor data (20 and 40 cm deep)
Full history in my blog