Centrifugal variable-rate fertilizer spreaders have attracted attention for their low cost, high efficiency, and reduced crop damage. To improve real-time response and fertilization accuracy, this study developed three actuator-driven feed mechanisms: gear–rack structure A, electric handspike B, and screw slider C. Kinematic models and a time-delay fertilization model were established to analyze lag effects. Performance tests calibrated fertilizer lag distances, actuator response times, and flow rate errors. Results showed that average lag distances for A, B, and C were 3.56 m, 1.85 m, and 2.72 m, with correction times of 1.99 s, 1.48 s, and 1.74 s, respectively. A positive correlation was found between application increment and actuator response time (TBi > TCi > TAi). Flow errors decreased then increased with feed rate, with minimum error between 250–380 g/s, and γBi > γAi > γCi. Structure C was selected for integration, and with a correction time of 1.74 s applied, the average fertilization error reduced to 9.67% and lag distance to 0.37 m. Spreading tests under ISO 5690 and ASAE S341.2 showed optimal uniformity at 300 g/s and 600 r/min, with coefficients of variation of 14.25% and 13.86%. An S-shaped variable-rate model achieved fitting accuracy with R2 values of 0.91 and 0.82 for increasing and decreasing rates, and a prediction error of 9.47%. This study provides a foundation for improving response and uniformity in centrifugal variable-rate fertilization systems.