If, for any reason, the installation of soil moisture sensors in unpracticable in your case, your Meteobot® can be equipped with a solar irradiance sensor. By taking into account solar irradiance data, as well as temperature, air humidity and wind, Meteobot® calculates how much water is evaporated from the soil and transpired by the plants every day (so called “evapotranspiration”). When you know the water losses from the soil for a certain period, you can find out how much you need to irrigate (e.g. 5 days x 4 liters evapotranspiration per day = need for 20 liters of irrigation).

irrigation evapotranspiration

Meteobot Meteostation