In the control circuitry diagram (Figure 4), it consists of four sections which are power supply and connector, timer, adjustable motor pump and relay. Two potentiometers (RV1 and RV2) act as control input for the control circuitry that initially set by user, where the timer and desired fertilizer volume were set after all parameters for desired EC, (ECd) have been considered. Potentiometer, RV1 for time duration input setting while potentiometer, RV2 for injector flow rate value control input. The timer using monostable timer circuit is used for control of irrigation by preprogramming for initiation and termination of fertilizer injection process. A monostable circuit produces a single output pulse or stable in just one state (output low) when triggered and the output high state is temporary. When the preset time is attained, a signal is extended from the timer to control circuitry for opening of the adjustable motor driver circuit by applying a positive supply on relay. Pin-3 becomes high, and relay is operated. When the preset time of pump operation has been reached, the pumps stop injecting the fertilizer. However, the solenoid valve remains on by refilling the tank until water level reaches the high level of tank. After the water level sensor reach the maximum level of mixing tank, the solenoid valve turns off to shut the the water supply then the timer circuit is reset for the next mixing cycle. This operation would be repeated run as long as the water level is at the lower level inside mixing tank.