Engineering properties of garlic bulbs essential for the design of garlic harvesting systems

Designing efficient machinery for ‘Yamuna Safed 5 (G-189)’ garlic requires evaluating its physical, mechanical, and field properties. Cultivated in sandy loam (10 × 30 cm spacing), the soil exhibited a bulk density of 1.79 g.cm-³, 14.80% moisture, and a 748 ± 14 kPa cone index. Average bulb depth was 55 ± 12 mm, and stem diameter was 10.20 ± 2.30 mm. Mechanical testing determined a maximum uprooting force of 29.33 ± 4.12 N and stem cutting forces from 28.15 to 69.35 N. Increasing operational velocity (20 to 40 mm.min−1) inversely reduced cutting energy by up to 74.20%. Biometrically, bulbs averaged 38.73 ± 2.60 mm (polar diameter), 42.45 ± 3.30 mm (equatorial diameter), and 32.08 ± 1.20 g (mass), with an oblate shape factor of 0.91 ± 0.07. Strong linear correlations (R2 = 0.85–0.91) between bulb mass and diameters offer precise grading parameters. Additionally, bulb bulk density was 460.0 ± 7.10 kg.m-³, and the angle of repose was 40.40° ± 3.50°. ANOVA confirmed cutting velocity significantly impacts maximum cutting load and energy, while stem diameter influences cutting energy and compressive extension. Ultimately, these crop thresholds directly informed the engineering specifications for a commercial harvester, establishing an 80 mm digging depth, 69.35 W cutting power, 38 N uprooting belt tension, and a 54° hopper angle to maximize efficiency and minimize damage.