Abstract: The present invention provides an apparatus and method for accurately controlling the amount of NH3 to be applied to a field by measuring the NH3 flow rate without condensing or cooling the NH3. The system includes a control station 12 on the vehicle with a tachometer 12A or a GPS system for providing a vehicle speed signal to a control panel 13. The control panel includes a toggle switch 17 for adjusting the opening or closing of a valve 52 in the flow line to regulate the flow through the system, although the control panel alternatively may automatically control the valve 52. The vehicle transports a tank 20 containing liquid NH3 and a tool bar 30 for distributing the NH3 to the soil. After flowing through the flow meter 40, 60, 130, the NH3 is conducted to the soil through a series of hoses, fittings, a distributor, and tubing. The flow meter transmits a signal to the control panel, which is converted to a corrected flow rate signal in response to a fixed value vaporization correction factor.