Purpose <p>This study investigates the effects of soil moisture content and mechanical impact on soil detachment efficiency from garlic roots to optimize post-harvest processing systems and provide quantitative design criteria for mechanical soil removal equipment.</p> Methods <p>Garlic samples (n = 180) with two moisture levels representing practical drying conditions (12% after 1-day drying and 7% after 2-day drying) were subjected to controlled drop tests from heights of 0.5, 1.0, and 1.5&#xa0;m. Impact variables including force, contact time, and energy were normalized by sample mass to ensure accurate comparative analysis across varying garlic and soil weights. Soil detachment ratios (SDR) were calculated and statistical analyses including ANOVA and t-tests were performed to evaluate the significance of observed differences.</p> Results <p>Drying markedly enhanced soil detachment. The 7% moisture samples consistently showed higher SDR than the 12% samples across all heights, with a maximum SDR of 43.1% at 1.5&#xa0;m—about 45% greater than the 29.8% at 12%. The effect of drop height was stronger under drier conditions (R² = 39.1%) than under wetter ones (R² = 12.1%). Drier samples exhibited a 2.5-fold higher maximum impact force per unit mass (3,649 N kg⁻¹ in comparison with 1,452 N kg⁻¹) and shorter contact times (0.0054–0.0058&#xa0;s compared with 0.0067–0.0131&#xa0;s).</p> Conclusions <p>Controlled drying substantially improves mechanical soil removal efficiency in garlic processing. The results provide quantitative design criteria for impact-based removal systems and highlight moisture management as a key factor for optimizing mechanized operations. These findings can also inform the mechanization of other root crops with similar soil adherence issues.</p>