A modular sprayer system for use with heavy-lift unmanned aerial vehicles includes a liquid storage tank for receiving and storing any type of agricultural products. A mounting unit is located along the top of the tank and includes hardware for securing the system to a UAV. Skid-type landing gear is permanently secured to the outside of the tank, and an electric pump is disposed within the tank. The location of the pump dampens movement of fluid within the tank during flight. One or more elongated booms are in fluid communication with the pump and terminate into dispensing units having one or more nozzles for releasing the fluid. A control unit is in electrical communication with one or both of the UAV to which the system is secured and a system operator. A tank level sensor and imaging systems are communicatively linked with the control unit.