This paper presents an agrochemical application system that could be incorporated into existing irrigating center-pivots. The system consisted of a hydraulic circuit with emitters, where the dose was individually controlled with variable valve timing. This paper describes the electronic control system, designed to be modular and distributed along the pivot. The main problem solved was the determination of the emitter’s absolute displacement to generate their adequate timing control. The paper ends with the test of a low-cost implementation of the complete system under real center-pivot operation.