An agricultural sprayer (1) with a pump (20), a boom (15) with a plurality of spray nozzles, a valve arrangement (28) associated with the boom, a feed conduit (25) for establishing fluid communication between an outlet of the pump (20), a return conduit (32) branching off from the feed conduit (25), a regulation valve (30), the regulation valve (30) applying a variable degree of throttling to the fluid flowing from the feed conduit (25) through the return conduit (32) and a controller (50) configured to be in receipt of a group of signals. The group of signals includes a signal from a pressure sensor (41) providing a signal representing the pressure of the fluid delivered to the valve arrangement (28), a flow sensor (42) providing a signal representing the flow rate of the flow to the valve arrangement (28), a regulation valve position sensor (31) sensing the position of the regulation valve (30), a pump speed sensor (27) sensing the speed of the pump (20) and a sprayer speed sensor sensing the speed of the agricultural crop and field sprayer (1). The controller (50) is configured to control the position of the regulation valve (30) in accordance with a plurality of operation modes, and the controller (50) is configured to automatically select an appropriate one of the operation modes, the plurality of operation modes including a full functionality mode and a plurality of fail-safe modes.
