An agricultural crop and field sprayer, said sprayer comprising: a sprayer fluid tank, a positive displacement pump, the inlet of the pump being in fluid communication with said tank, a boom divided in boom sections and each boom section being provided with a plurality of spray nozzles, a valve arrangement associated with said boom sections, a feed conduit for establishing fluid communication between an outlet of said pump and said valve arrangement, said valve arrangement being configured for selectively connecting the feed conduit to a bypass conduit or to one or more of the boom sections, a return conduit branching off from the feed conduit, a regulation valve, said regulation valve applying a variable degree of throttling to the fluid flowing from the feed conduit through said return conduit, said variable degree of throttling depending on the position of the regulation valve, a controller, said controller being configured to be in receipt of a group of signals from sensors associated with the agricultural sprayer, characterized by said controller being configured to control the position of said regulation valve in accordance with a plurality of operation modes, and said controller being configured to automatically select an appropriate one of said operation modes, said plurality of operation modes including a full functionality mode and a plurality of fail-safe modes, said controller being configured to operate said agricultural crop and field sprayer in said full functionality mode when all the signals of said group of signals are available to said controller, said controller being configured to register the availability of the sensor signals, and said controller being configured to automatically switch to operate said agricultural crop and field sprayer in one of plurality of the fail-safe modes when one or more of the signals of said group of signals is not available to the controller. a sprayer fluid tank, a positive displacement pump, the inlet of the pump being in fluid communication with said tank, a boom divided in boom sections and each boom section being provided with a plurality of spray nozzles, a valve arrangement associated with said boom sections, a feed conduit for establishing fluid communication between an outlet of said pump and said valve arrangement, said valve arrangement being configured for selectively connecting the feed conduit to a bypass conduit or to one or more of the boom sections, a return conduit branching off from the feed conduit, a regulation valve, said regulation valve applying a variable degree of throttling to the fluid flowing from the feed conduit through said return conduit, said variable degree of throttling depending on the position of the regulation valve, a controller, said controller being configured to be in receipt of a group of signals from sensors associated with the agricultural sprayer, characterized by said controller being configured to control the position of said regulation valve in accordance with a plurality of operation modes, and said controller being configured to automatically select an appropriate one of said operation modes, said plurality of operation modes including a full functionality mode and a plurality of fail-safe modes, said controller being configured to operate said agricultural crop and field sprayer in said full functionality mode when all the signals of said group of signals are available to said controller, said controller being configured to register the availability of the sensor signals, and said controller being configured to automatically switch to operate said agricultural crop and field sprayer in one of plurality of the fail-safe modes when one or more of the signals of said group of signals is not available to the controller.