Simulation of the micro-dynamics in soil–cornstalk–disc interactions using the discrete element method

Understanding the interactions between soil, crop residue, and tillage tools is essential for improving tillage quality in conservation agriculture. This study developed a discrete element model to simulate soil–cornstalk–disc interactions, replicating the cutting of corn stalks by a concave disc in sandy loam soil. A soil bin experiment was conducted using a notched concave disc to cut corn stalks, measuring draft forces, vertical forces, and corn residue cutting effectiveness. Experimental data were used to calibrate and validate the model. After validation, the model was applied to analyse the micro-dynamic behaviours of corn stalks and soil under varying soil bulk densities and disc types. Three key parameters calibrated for the corn stalk model were 2.0 × 10⁹ N m⁻¹ for particle normal stiffness, 8.0 × 10⁶ Pa for bond tensile strength, and 0.5 for particle friction coefficient. The model effectively predicted corn stalk cutting effectiveness, draft force, and vertical force, with an overall relative error of 16.4%. Micro-dynamic analysis showed that as soil bulk density decreased (within a range of 1.06 to 1.52 Mg m⁻³), corn stalk sinkage and soil supporting force increased, while corn stalk intrusion force decreased. Compared to the notched disc, the plain disc exhibited greater corn stalk sinkage and soil supporting force but lower corn stalk intrusion force. This research provides a validated model for simulating soil–cornstalk–disc interactions, enhancing the understanding of disc performance in cutting crop residue.