It’s an underground Capacitive probe (60cm or 80 cm /32 mm (1.25 ”)). It measures soil moisture at 6 depths depending on the crop : 10 cm, 20cm, 30cm, 40cm, 50cm, 60 cm and /or 80 cm (60cm recommended for vegetables and 80cm for trees).
Measured data are sent to a datalogger than used by the final user.