Abstract: Aimed at the problem that traditional fertilizer distribution devices in orchards had difficulty in real-time adjustment of the fertilization amount, this research undertook a comprehensive study to develop an advanced fertilization solution. The core of this study was to design a chain - type ditching and fertilizing machine and propose a dual - parameter joint control fertilization scheme, accompanied by the development of a sophisticated control system.The control system integrated the BeiDou Navigation Satellite System (BDS) technology. By integrating BDS, the tractor could achieve automatic driving, greatly improving the efficiency and precision of the fertilization process. Through satellite messages, the system could accurately obtain the longitude and latitude coordinates of the orchard area. Based on these coordinates, the system could precisely determine the appropriate fertilization amount according to the specific soil conditions and crop requirements in that area. At the same time, considering the forward speed of the tractor, the system looked up a pre - established table to obtain the dual - parameter adjustment information for the fertilizer outlet height and the fertilizer discharge speed. This dual - parameter control method ensured that the fertilization process could be precisely adjusted according to different situations in the orchard.In terms of the adjustment of the fertilizer outlet height, stepper motors were used in conjunction with displacement sensors. The stepper motor provided accurate power for the height adjustment, and the displacement sensor could precisely measure the actual height of the fertilizer outlet. By comparing the measured value with the target value, the system could make timely adjustments to ensure that the fertilizer outlet height was always at the optimal position. For the regulation of the hydraulic motor speed, a position - type proportional integral derivative (PID) control method was adopted. The PID controller could adjust the opening degree of the proportional speed control valve in real - time according to the deviation between the actual speed and the target speed, thereby achieving real - time regulation of the hydraulic motor speed. To optimize the performance of the PID controller, a joint simulation using AMESim and Matlab/Simulink was carried out. Through this simulation, the PID parameters could be accurately tuned. In the static calibration test, a series of experiments were conducted to obtain the corresponding relationship between the motor speed and the duty cycle. After that, speed adjustment experiments were carried out to verify and correct the simulation results. Through repeated tests and adjustments, the PID parameters were re - tuned to achieve the best control effect. The re - tuned parameters were K_p = 0.029, K_i = 0.05, and K_d = 0.000 7. In order to accurately test the speed - tracking performance of the system, tests were conducted under dynamic load conditions at low, medium, and high speeds. The results showed that all three speeds could achieve rapid responses. For example, the overshoots at low, medium, and high speeds were 16, 2.28, and 2.3 r/min respectively. And the time to reach the steady state was 5.5 s, 2 s, and 1.5 s respectively. Moreover, the steady - state errors at all three speeds were relatively small, which indicated that the system had good stability and control accuracy.Finally, fertilization tests were carried out to evaluate the overall performance of the system. It showed that both the fertilizer outlet height and the fertilizer discharge speed could be adjusted in real - time according to the requirements. In the fertilization areas with target fertilization amounts of 2.75 and 3.61 kg/m, the average fertilization amounts were 2.824 and 3.810 kg/m respectively. The relative errors between the average fertilization amounts and the target fertilization amounts were 4.590% and 5.546% respectively, and the variation coefficients of the fertilization amount were 7.487% and 4.720% respectively. These results met the requirements for fertilization accuracy, which meant that the designed system could effectively solve the problem of real - time adjustment of the fertilization amount in orchards.In conclusion, the research findings provided a valuable reference for variable organic fertilizer application in orchards. This new - type fertilization system had great potential for application in the agricultural field, which could improve the efficiency and quality of fertilization.