Simulation of canola seedling emergence dynamics under different soil compaction levels using the discrete element method (DEM)

Abstract

Understanding the dynamics during the seedling emergence process has important implications in creating favourable soil conditions for improved plant emergence. In this study, a model was developed using the discrete element method (DEM). The model simulated the emergence process of a canola seedling under six different soil compaction levels (L1 to L6). In the model, soil was represented by 2-mm spherical particles with bonds between particles. The bond parameters were calibrated using experimental data. The calibrated model was used to simulate the dynamics of the emergence process under different soil compaction levels. Depending on the soil compaction level, simulation results show that the calibrated bond normal stiffness is in the range of 3.10e+ 10–5e+ 11 N·m−3. The emerged canola seedling exerted great contact forces to the surrounding soil particles, which produced a dynamic influencing zone in the soil. The influencing zone was greater at higher soil compaction levels. The predicted canola emergence force (the total contact force between seedling and soil particles in the vertical direction) increased with the soil compaction level. The average emergence forces were 4.04, 5.81, 7.59, 8.18, 8.43, and 9.36 N for L1 to L6, respectively. The soil compaction levels (except for L1) were excessive for canola production, as they resulted in unacceptably low emergence rates. The study advances our understanding of the dynamics in the plant emergence process in a micro-scale soil environment.