A vertical variable cavity organic fertilizer and compound fertilizer apparatus were designed according to tobacco farming requirements to overcome issues of unstable fertilizer discharge and blocking in the fertilizer disk of an existing fertilizer apparatus. The structure and working principle of the fertilizer apparatus were described. Combined with the principle of anti-arch and the requirements of fertilizer application, the structure size of the fertilizer apparatus was determined. Using the opening degree and rotational speed of the fertilizer disk as the test factors and the fertilizer rate and variation coefficient of fertilizer application rate as the indices, the EDEM was used to conduct the single factor test and obtain the appropriate rotational speed range. The results indicated that the variation coefficient of the fertilizer uniformity apparatus was 0.96–5.22% under different rotation speeds and fertilizer disk openings, which satisfied design requirements. The orthogonal experiment explored the interaction between rotational speed and the opening. The influence of the opening adjustment on the fertilizer application rate and the coefficient of variation of uniformity were greater than the change in fertilizer disk speed. The bench and field tests aligned with the simulation test. These findings provide a reference and theoretical basis to design a fertilizer apparatus.

Cultivation and hilling are important steps in crop field management and provide an important guarantee of crop quality and quantity. With the aim of addressing how the soil flow direction of a traditional cultivation and hilling machine is difficult to control, and because it is difficult to achieve high ridge soil cultivation, among other issues, the components of the soil flow direction control of a hilling machine was designed. The components of the soil flow direction control consisted of a soil-feeding plough device, spiral knives and guide cover devices, etc. The design and analysis of the guiding parts for the two tools of the soil-feeding plough device and the spiral knife were performed to obtain an appropriate guide wall and helix angle. The guiding principle in the flow direction control components was analyzed. The design of the guide wall adopts the torsional columnar plough surface, and the elementary line angle changes from stable to increasing. The analysis of spiral milling showed that when the spiral angle is large, the milling effect is better. According to the discrete element method, the working part of the machine-soil interaction model was established. EDEM software was used to simulate the control components for the soil flow direction of the hilling machine for compound cutting. The design method with a two-factor comprehensive test was used to study the linear velocity along the outer part of the spiral knife and the influence of the forward velocity of machine of the implement on the soil cultivation effect. The results of the discrete element simulation showed that both the linear velocity along the outer part of the spiral knife and the forward velocity of the machine have extremely significant effects on the transportation of particles to the ridge top and the hilling thickness. Following multiple comparisons of the average hilling thickness with different linear velocities along with the outer spiral knife and different forward velocities of the machine, it is concluded that the performance of the machine is better when the linear velocity along the outer spiral knife is 3.01 m/s and the forward velocity of the machine is 0.7 m/s. The research conclusion had great theoretical value and practical significance for the design of the machine, which worked for cultivation and hilling. Keywords: compound cutting, hilling machine, flow direction control, discrete element method, design DOI: 10.25165/j.ijabe.20221503.5857 Citation: Tong Z W, Li L H, Zhang X L, Chen Y, Liu X C, Zhou P L, et al. Design and experiment of the components for soil flow direction control of hilling machine based on EDEM. Int J Agric & Biol Eng, 2022; 15(3): 122–131.

Rural domestic waste slag is often used to prepare organic fertilizer, thereby improving the environment and saving resources. The mixing of the raw materials and fermentation bacteria is key to the preparation of organic fertilizers. In the organic fertilizer continuous conveying device designed in this study, a paddle was substituted for a screw blade for transporting the material to improve the mixing performance. A discrete element method (DEM) model was established for the device. The influences of the paddle rotational speed n and paddle angle α were studied. The simulation results showed that mixing performance was improved when the paddle angle α was 45° and the paddle rotational speed n was 75 rpm, with an RSD of 15.96%. The larger the paddle rotational speed n, the larger the average normal contact force, and the smaller the influence of the paddle angle α. In addition, the paddle rotational speed n and paddle angle α could affect the speed of the particles in all directions in the device. The trajectory of a single particle in the device was analyzed, and it was found that changing the paddle parameters could improve the path length and improve the mixing performance. The research results lay the foundation for designing reasonable paddle parameters.