Assessment of Soil Mixing Ratios during Tillage: A Combined Simulation and Experimental Study

초록

Soil mixing ratio is an important indicator of soil structure improvement, fertility enhancement, and mechanical stability during rotary tillage. However, accurately quantifying soil mixing remains challenging because of complex soil–tool interactions. This study evaluated soil mixing ratios using a combination of discrete element method (DEM) simulation and experimental image processing. Soil bin experiments and DEM simulations were conducted under different tillage conditions using a four-flange J-type blade rotary tiller operating in sandy loam soil (57.5% sand, 25.6% silt, and 17.2% clay). A full factorial design included three forward speeds (0.2, 0.4, and 0.6 m/s), three tillage depths (50, 80, and 110 mm), and a fixed rotational speed of 270 rpm. The DEM model was developed to simulate soil–tool interactions and validated using experimental measurements. Soil mixing ratios from experiments were determined by processing digital images of soil cross-sections with grayscale threshold values of 180, 190, and 200. Model performance was assessed using RMSE, R², and MAE. Results indicated that threshold selection significantly affected soil mixing estimation, with a grayscale value of 190 producing the closest agreement with DEM predictions. The findings demonstrate that DEM can reliably predict soil mixing behavior and that optimized image processing improves experimental accuracy, providing a practical framework for evaluating and optimizing rotary tillage performance. © 2026, Asian Association for Agricultural Engineering. All rights reserved.

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