Analysis of the engineering properties of sorghum (sorghum bicolor (l.) moench) seeds for the design optimization of a tractor-drawn multi-crop planter

Abstract

Traditional planting systems often lack adaptability to diverse seed morphologies, compromising seed placement accuracy and crop productivity. This study evaluates the engineering properties of three sorghum varieties; ‘Dekeba,’ ‘ESH-4,’ and ‘Melkam’ to optimize critical components of tractor-drawn multi-crop planters for semi-arid regions. Geometric dimensions (major, intermediate, minor diameters) of 100 seeds per variety were measured with digital calipers. Geometric and gravimetric properties were measured and analyzed, revealing significant varietal differences. Findings revealed distinct component-level optimization needs for each variety. The seed metering mechanism, elongated seeds of ‘ESH-4’ (Geometric mean diameter: 4.16 mm) require cell dimensions of at least 4.5 mm in length and 2.8 mm in depth for accurate singulation. ‘Melkam,’ with its high flakiness ratio (69.39 ± 4.29%) and thousand-seed mass (34.71 g), demands a reinforced, wear-resistant drive mechanism and a hopper with a steep wall slope (≥ 450) integrated with a mechanical agitator to prevent bridging. The high sphericity of ‘Dekeba’ (80.66 ± 3.27%) necessitates metering cells with rubber gaskets and smooth seed tubes to mitigate roll-out and bounce. Furthermore, hopper design is governed by flow properties, where ‘ESH-4’s high angle of repose (33.070) accommodates a fixed, steep hopper, while ‘Melkam’ requires active agitation. This study provides a scientific framework for designing seed-specific planter components that enhance singulation accuracy, reduce seed damage, and improve field efficiency. These findings contribute to advancing precision planting technologies and strengthening food security strategies in semi-arid agricultural systems.