Abstract: Orchard ring-furrow fertilizer applicator can be subjected to complex and heavy-duty working conditions. The critical challenge is often required for the precise control of the curve fertilization trajectory. In this study, a ring-furrow control system was designed for the multi-segment arc trajectory during fertilization. The fertilization trajectory was precisely regulated by the transverse variable-speed telescopic motion of the furrow opener, in order to coordinate with the constant-speed linear forward motion of the fertilizer applicator. Firstly, the systematic analysis was implemented to determine the drive system for the transverse telescopic motion of the furrow opener, according to the variable-speed motion under the multi-segment arc trajectory. Three hydraulic circuits of the speed control were utilized to drive the transverse telescopic movement of the furrow opener. AMESim simulation was also performed to take the adjustment time and linear error as the indices, including the circuits with the proportional speed control, throttle, and directional valve. Secondly, the co-simulation system model was established with the segmental PID (proportional-integral-derivative) control using AMESim-Matlab platform. A hydraulic drive system model was integrated for the variable-speed telescopic motion of the furrow opener. A segmental increment PID control model was utilized under the working conditions, in order to meet the control accuracy in the full segment of the trajectory. Finally, the fertilizer-spreading and furrowing tests were conducted with the curve trajectory, in order to verify the control system. The results showed that the adjustment time was 0.02 s and 0.05 s for the extension and retraction speeds of the hydraulic cylinder in the proportional directional valve circuit to the step-change from 0 to 0.28 m/s, respectively. The linear errors of the extension and retraction speeds within 0−0.4 m/s were 0.16% and 0.07%, respectively. There was a significantly lower adjustment time and linear errors in the proportional directional valve circuit, compared with the proportional speed control valve or throttle valve. There were optimal dynamic and steady-state speed control features. The AMESim-Matlab co-simulation showed that the correlation coefficients between the actual and the target displacement curves of the furrow opener's transverse telescopic movement were all greater than or equal to 0.99986, with all root mean square errors less than or equal to 0.00188 m under four typical working conditions such as no-load, normal operation, compact soil, and sudden resistance. The segmental PID control also obtained the control accuracy for the full segment of the fertilization trajectory, indicating the excellent adaptability to the four typical working conditions. The fertilizer spreading test with the curve trajectory showed that the relative errors of the closest distance between the fertilization trajectory and the tree row, the base circle radius of the ring furrow, and the tangent arc radius were 1.76%, 1.27%, and 2.65%, respectively. The high control accuracy of the trajectory parameters was achieved through better adaptability to the plant spacing. The curve furrowing test indicated that the correlation coefficients between the actual and the target displacement curves of the furrow opener's transverse telescopic movement reached 0.9950 and 0.9991, respectively, with the root mean square errors of 0.0103 and 0.0078 m, respectively, for the plant spacing of 1.3 and 2.3 m, respectively. The control accuracy of the system fully met the requirements under the complex and heavy-duty working conditions of the curve furrowing. The fertilizer-spreading and furrowing tests with the curve trajectory verified that the control model was constructed to realize the mechanized operation of the curve furrowing and ring-furrow fertilization in orchards. The findings can also provide the basis and reference for the trajectory control of the working components of the agricultural machinery. A great contribution was also made for the technological development of the mechanized ring-furrow fertilization in orchards.