By injecting a chemical fluid and a carrier fluid directly at each nozzle, and by then mixing the fluids at each nozzle to produce a mixed fluid, an improved spray system may be provided which does not contaminate the tank or distribution system with chemical fluid and which allows improved spraying with minimal delay. Accordingly, a system is provided on a field sprayer for independently controlling the flow rate of concentrated chemical fluid to individual spray nozzles using a high pressure chemical distribution rail or loop routed to each nozzle and solenoid injection valves to control the flow of chemical fluid to each nozzle independently.