Seed motion characteristics and seeding performance of a centralised seed metering system for rapeseed investigated by DEM simulation and bench testing

Abstract

The landing position of rapeseed distributed from a centralised seed metering system directly affects seeding quality. However, the mechanisms involved in interaction between seeds and tubes are unclear. This study examined parts of the seeding process that are unmeasurable based on DEM simulation and used bench tests to determine seed distribution uniformity. The effects of the type and diameter of seed tube, seed-dropping height and forward velocity on seed motion characteristics, and seeding performance were investigated. Simulation results revealed that the seed tube diameter and seed-dropping height had a significant impact on the distribution position of seeds. For the seed tube diameter of 15 mm and seed-dropping height of 1100 mm, the average variance coefficient of seeding uniformity was ≤ 15.0%. The collision and bounce between seed and the distribution tube changed seed motion trajectory, causing the variations in seed velocity and a decrease in seed deposit uniformity. The bench tests showed the variance coefficient of seeding uniformity varied between 27.86% and 32.87% with the average ridge spacing on ridges of 114.9 mm when the diameter of smooth tube was 15 mm. The variance coefficient of seedlings distribution was 4.14%–20.17% in field experiments. The results contributed to improving knowledge of the causes of seed distribution variability and should help optimise the parameters of centralised seed-metering system.