Method for determining the optimal quantity of water to be provided to a plot under cultivation comprising the following steps: a) acquiring information about the soil water content at the current time (D i-1 ) b) acquiring information about the soil features (TAW, RAW) c) acquiring information about the kind of crop present, and in particular its developing stage (Kc) and the level of water stress which the same is able to undergo according to the developing stage (MAD) d) acquiring information about the weather conditions foreseen in said time interval e) calculating, according to the information acquired in steps a) and b), a parameter indicating the level of water stress in the soil at the current time (Ks i-1 ) f) calculating, according to said parameter calculated at point e) and to said information acquired at points c) and d), a parameter indicating the water quantity lost by the soil due to evaporation and transpiration (ETci) g) calculating, according to said parameter calculated at point f), a parameter indicating the water stress in the soil at the time following the current one (Ks i ), in the hypothesis of no irrigation h) determining the water quantity to be provided at the current time (IRRi) in order that the value of said parameter calculated at point g) takes a value such that the water stress is lower than the water stress level that the crop is able to undergo (MAD).
