Sensecap2105 calibration for sandy soil

Hi ! i purchased sensecap2105 which i want to use for different type of soils including sandy, clay and so on. How can i calibrate this sensor since it seems it is not able to show EC for sandy soil while the soil moisture is displayed. my need is for application where soil moisture start from 20 wt%.
Thakn you fo ryour help !
Regards