# Optimal Design and Experiment of Corn-Overlapped Strip Fertilizer Spreader
## 1 Introduction  
China's geographic environment, where hilly mountainous areas account for 43% of the complex landscape, restricts the development of agricultural mechanization [1]. Excellent corn fertilizer chasing machinery can not operate in the field, and due to the lack of a small fertilizer spreading device, fertilization is still dominated by manual spreading [2]. Uneven spreading of fertilizer can also lead to low fertilizer utilization, reduce the quality yield of maize, and cause problems such as the environmental pollution of soil slab [3, 4]. Therefore, it is necessary to study the corn fertilizer fertilization device in hilly areas to enhance the spreading efficiency, increase the emergence rate, and improve the soil environment of the seed bed. The mechanical fertilizer spreading method is mainly divided into strip application and spreading; the inline gravity type belongs to strip application, applying fertilizerwithout a power source and low fertilizer utilization, and the centrifugal spreading type belongs to spreading, and fertilizer spreading needs a power source [5; 6]. In recent years, the discrete element method has been used to simulate and analyze the interaction between agricultural bulk materials and mechanical equipment to good effect [7], providing a new means of digital design for modern agricultural equipment. Especially in the application of fertilizer discharges, fertilizer application devices and fertilizer spreading devices are more common. Researchers have conducted many studies on fertilizer spreading devices. [PERSON] [8] et al. designed an auxiliary roller for the side-throwing of organic fertilizer on the opposite swashplate and studied the influence of the roller speed, spiral angle, and blade number on the uniformity variation coefficient using the discrete element method; [PERSON] [9] et al. designed a pneumatic seed fertilizer cavity application device and used the coupled CFD-DEM method to clarify the flow field distribution within the fertilizer delivery mechanism and its effect on the movement of fertilizer masses under different delivery paths, which ultimately improved the fertilizer yield; [PERSON] [10] et al. designed fertilizer discharge wheels with different groove shapes and number of groove columns, and used EDEM simulation and bench tests to test the discharge range of each wheel, as well as the pulsation and accuracy when discharging fertilizer so as to preferably select a fertilizer discharge wheel that meets the requirements of UAV fertilizer application; [PERSON] [11] et al. designed a spiral cone centrifugal fertilizer application device, based on a discrete element approach to optimize the curved conical discs that affect the uniformity of the fertilizer application device; [PERSON] [12] et al. designed a dual-frequency fertilizer applicator and used the discrete element method (DEM) to model the operating process of the applicator to examine the effect of machine parameters on the ratio of starting fertilizer to base fertilizer discharged and the separation distance of the fertilizer band. The above-mentioned studies on discrete elements in agricultural machinery all provide good technical tools and methods for this study. Overall, the existing research provides further research for ample fertilizer spreading devices. However, fewer small fertilizer-spreading machines have fully considered non-powered drives. For the complex terrain of hilly mountainous areas, choosing a minor, lightweight, low-power fertilizer spreading device is more suitable [13; 14]. Therefore, based on the gravity inline fertilizer spreading technology, the development of new fertilizer spreading machinery structures to increase the spreading width and fertilizer utilization rate under the premise of low power consumption deserves more in-depth research. Therefore, this article combined the gravity inline fertilizer spreading method and proposed a corn-overlapped strip fertilizer spreader without an external power source.