Assessment of Physical Properties of Black Gram and Green Gram Seeds in Relation to the Design of Seed Metering Mechanisms

In 2023, a comprehensive study was carried out at the Department of Agricultural Engineering, IARI, New Delhi, India, focusing on the investigation of vital physical properties encompassing size, sphericity, test weight, bulk density, true density, coefficient of static friction, and angle of repose for black gram and green gram seeds. Black gram seeds were characterized by mean dimensions of 4.90 mm (length), 3.74 mm (breadth), 3.57 mm (thickness), and a geometric mean diameter of 4.02 mm. In contrast, green gram seeds exhibited corresponding values of 5.08 mm, 4.06 mm, 3.99 mm, and 4.45 mm. Sphericity percentages were quantified as 82% for black gram and 86% for green gram. Mean bulk density measurements of 0.86 g/cc (black gram) and 0.87 g/cc (green gram) were accompanied by true density values of 1.36 g/cc and 1.38 g/cc, respectively. The mean angle of repose measurements were recorded as 24.06° (black gram) and 23.94° (green gram). The mean coefficient of static friction exhibited variability across different materials: 0.50 (aluminum), 0.45 (mild steel), 0.47 (galvanized iron), and 0.60 (plywood) for black gram seeds; while for green gram seeds, corresponding values were 0.48, 0.43, 0.45, and 0.57. Additionally, the mean thousand-grain weight was found to be 41.82 g for black gram and 46.18 g for green gram.