A liquid spraying system having an elongated liquid supply boom and a plurality of spray nozzle assemblies. The spray nozzle assemblies have a compact design with a nozzle body having a liquid inlet and a first spray nozzle carrying liquid outlet section on opposite upper and lower sides, second and third spray nozzle carrying liquid outlet sections disposed in transverse relation to the supply boom； and first and second check valve supporting sections disposed parallel to the liquid supply boom. A first of check valves is operable for controlling liquid flow from the supply boom to one or both of the second and third spray nozzles, and a second check valve is operable for controlling liquid flow from said liquid inlet to said first spray nozzle. The illustrated check valves are operable in response to the pressure of the supply liquid.
