Discrete Element Modeling and Experimental Validation of Soil Covering and Compaction Processes in the Precision Sowing of Panax notoginseng

Abstract

Highlights A DEM model of the soil covering–compaction process during the precision sowing of Panax notoginseng was established. The interactions among the seed, soil, and soil covering–compaction device were simulated using a DEM. The relative error between the DEM simulation and soil bin tests was only 6.06%. Abstract. In this study, Yunnan clay loam with a moisture content of approximately 25% was selected as the research material to increase the accuracy of discrete element method (DEM) simulations of the soil covering and compaction process during Panax notoginseng precision sowing under Yunnan clay loam conditions. The physical parameters of the clay loam were determined experimentally, and the Hertz–Mindlin with Johnson–Kendall–Roberts (JKR) contact model in EDEM software was used to conduct simulation tests to calibrate the relevant parameters. Through a Plackett–Burman design with the soil angle of repose as the response variable, the soil–soil static friction coefficient, soil–soil rolling friction coefficient, and JKR surface energy were identified as the primary factors affecting the angle of repose. Building on this information, a Box–Behnken design was used to establish a regression model linking these significant factors to the soil angle of repose. Using the measured angle of repose (29.4°) as the optimization target, the optimal parameter combination was determined as follows: a static friction coefficient of 0.8, a rolling friction coefficient of 0.05, and a JKR surface energy of 0.13 J/m 2 . With this optimal parameter combination, the DEM simulated interactions among soil particles, Panax notoginseng seeds, and the soil covering and compaction device, yielding the soil covering thickness. Validation via Soil bin test demonstrated a relative error of 6.06% between the simulated and measured average soil covering thickness, indicating that the calibrated parameters can reliably represent the soil covering and compaction process during the precision sowing of Panax notoginseng. These results provide a theoretical basis for optimizing and improving soil covering and compaction devices for Panax notoginseng seeders. Keywords: Discrete element method, Precision sowing of Panax notoginseng, Soil bin test, Soil covering and compaction process, Yunnan clay loam.