Objective In view of the poor adaptability of the current fertilizer control system, and the need to recalibrate after changing fertilizer types and other problems, a fertilization control system with adaptive calibration function was designed.

Method The volume density was introduced into the conventional calibration formula and a new calibration formula for various fertilizers was established and verified by experiments. With fertilizer type and displacement as experimental factors, fertilizer discharge accuracy and coefficient of variation as experimental indexes, and conventional fertilizer control system as control, the performance of the adaptive fertilizer control system using the new calibration formula was tested.

Result The determination coefficient of the new displacement relation formula was 0.996, and the average relative error was 3.63%. Under the target displacement of 2000 to 12000 g/min in the adaptive control system using this formula, the maximum error of the discharge rate of spherical granular fertilizer was 5.46%, and the coefficient of variation was less than 3.54%. When using the conventional fertilizer control system (using compound fertilizer for calibration), the maximum relative error was 4.92% for compound fertilizer, 10.92% for slow-release mixed fertilizer and 50.11% for calcium superphosphate fertilizer.

Conclusion Compared with the conventional fertilization control system, the adaptive fertilization control system can adapt to a variety of fertilizers, and the displacement is accurate, which is helpful to improve the working efficiency and quality of the fertilizer applicator.