Design and Investigation of a Sweep Coulter with a Semi-Ellipsoidal Scatterer for Lateral Distribution of Wheat Seeds

Achieving uniform lateral seed distribution across the working width of a sweep coulter remains a challenge in intrasoil-broadcast sowing. This study presents a sweep coulter equipped with a stationary semi-ellipsoidal seed scatterer with two symmetrical radial through-slots. The research combined theoretical analysis of seed motion, Discrete element method (DEM) simulations, laboratory experiments, and statistical analysis. The theoretical model described the dependence of lateral seed-flight distance on the scatterer geometry and impact conditions. DEM simulations provided qualitative mechanistic evidence, supplemented by descriptive quantitative results, of lateral flow division and ballistic seed motion after impact. A three-factor, three-level full factorial design 33 comprising 27 experimental runs was used to investigate the effects of scatterer base diameter (d), mounting height (h), and scatterer height (H) on the coefficients of variation in lateral seed distribution and total seeding. Based primarily on the Y1 response surface, the parameter ranges d = 39–41 mm, h = 17–19 mm, and H = 19–21 mm were selected as a compromise range within the investigated design space. Y2 was considered only descriptively because its quadratic model was not statistically significant. The theoretical model indicated a range-maximizing rebound angle of approximately 22.6–23.2° under the investigated conditions. ANOVA showed that the Y1 model was significant (F(9,17) = 50.571, p < 0.001), with base diameter having the strongest linear effect. The Y2 model was not significant (F(9,17) = 1.867, p = 0.128) and was interpreted descriptively. The results show the effects of the scatterer geometric parameters within the investigated design space and provide a basis for further experimental evaluation of the proposed coulter design.