Optimized design and experiment of a controllable rotary tube strip fertilizer spreader for hilly mountainous terrain

The existing fertilizer spreader has suboptimal performance in terms of fertilizer uniformity, lack of controllability of fertilizer spreading width, low utilization rate, and inability to meet the requirements of hills, mountains, and other complex terrains. In response to these shortcomings, we have developed a rotary tube fertilizer spreader for mountainous terrain. This device uses a fertilizer trajectory based on the drop distribution of overlapping prolate cycloids, which enables uniform fertilizer application in both the transversal and longitudinal directions. Based on an analysis of the structure and operating principles of the device, Table L₉ (3⁴) was selected for orthogonal array testing, and the results showed that the transversal fertilizer distribution uniformity (Y₁) and the longitudinal fertilizer distribution uniformity (Y₂) were 14.24% and 12.75%, respectively, when the number of rotating tubes was Z = 3, the angle θ of the rotating tubes with respect to the vertical was 50°, and the length of the rotating tubes was L = 100. The results of the simulation experiments were validated through bench experiments, and the relative errors of the coefficients of variation of traversal and longitudinal fertilizer distribution uniformity in the bench verification experiments were 11.45% and 2.8%, respectively. This demonstrated that the results of the simulation experiments were reliable. A mathematical model was constructed through bench experiments, in which the width of transversal fertilizer spreading (y) was regulated by operating parameters such as the rotational speed of the rotary tube (n) and the height of the tube mouth from the ground (h). The fitting results showed a corrected coefficient of determination of 0.9906. The experimental results were in agreement with the fitted results, thus adapting to crops with 40 cm to 160 cm spacing between rows. This study offers a theoretical foundation for the design of a rotary tube strip fertilizer spreader.