System and method for the automatic adjustment of an agricultural implement using a measuring light screen

System for adjusting the height of an agricultural implement, comprising an arm that can be controlled so as to raise and lower the agricultural implement, a height measuring sensor mounted on the arm and positioned in front of the agricultural implement in a direction of travel of a vehicle intended to be equipped with the arm, and a calculator configured to provide a control set point for the height of the arm on the basis of the measurements obtained by the height measuring sensor, wherein the height measuring sensor is a light screen device formed by an emitter in the form of a column of light sources (S1, S2, Sm) and a receiver in the form of a column of photoreceptors, the emitter and the receiver being mounted on the arm facing one another and extending along their longitudinal axis, perpendicularly to the ground in order to make it possible to measure the height of plants located therebetween.