The present invention provides an agricultural sprayer comprising: a tank for holding a liquid; a plurality of nozzles arranged along a spray boom and fluidly connected to the tank; a pump for transferring the liquid from the tank to the nozzles; a control valve for controlling the pressure of the liquid being transferred from the tank to the nozzles by the pump; means for determining a baseline parameter of the control valve; and a controller for controlling the parameter of the control valve dynamically relative to the baseline in response to change of one or more variables.
