Optimization of operating angles of disc coulters for maize residue management using discrete element method

Disc coulters are vital in conservation agriculture as effective tools for managing crop residues. Their operating angle parameters significantly influence the performance and effectiveness of disc coulters. A soil-disc coultermaize residue interaction model was developed using the discrete element method. The model was validated against field test results, demonstrating an overall error ranging from 4.21 to 12.31%. Central Composite Design simulated experiments were conducted to optimize the disc and tilt angle parameters for wavy, notched, and plain disc coulters. Four objectives, including draft force (FD), soil disturbance area (ASoil), flat residue-cutting efficiency (RFC), and standing residue-cutting efficiency (RSC), were selected for optimization. The simulation results showed that increasing the disc angle had a significant positive effect on FD and Asoil while also strengthening the sliding cutting action of the discs, resulting in higher RFC and RSC. Each disc type exhibited different trends in tillage performance with increasing tilt angle. The optimal angle parameter combinations for the three discs were determined as follows: wavy disc (5 degrees tilt angle, 7.5 degrees disc angle), notched disc (5 degrees tilt angle, 0 degrees disc angle), and plain disc (10 degrees tilt angle, 12.5 degrees disc angle). The average error between simulation and measurement results under the optimal parameters was less than 9%. Among the three discs, the wavy disc coulter is recommended as the preferred choice since its higher RFC and RSC values by 22.1-43.6%. The findings provide useful insights into optimizing parameters of residue management tools and understanding the interaction between soil-engaging components and residue-covered soil in conservation tillage.