The method involves setting (1001) supply reference pressure (Pr) for tubes. A product i.e. water, is pulverized (1002) using supply setpoint pressure of the tubes as the reference pressure and by measuring supply pressure of the tubes. Flow of pesticide to a slope is measured (1003) using a flow meter. A modeling parameter is calculated (1004) according to a value of the measured flow and a value of the measured supply pressure of the tubes or reference pressure. A value of the calculated parameter is corrected (1006) by taking account of density of the pesticide. Independent claims are also included for the following: (1) a method for controlling a system of spreading of pesticide of ground or culture (2) a spreading system.
