Experimental evaluation of a fluted feed roller metering device performance in a pneumatic grain drill for rapeseed planting

In the present study, the application feasibility of an air-assisted centralized metering device equipped with a fluted feed roller was investigated. The performance of the proposed metering device for rapeseed planting was evaluated in the laboratory. For this purpose, effects of rotational speed (n) of the metering device shaft (at levels of 46.5, 48, 79, and 96 rpm), active roller length, L, (at levels of 1/6, 1/4, and 1/3 of the total length of the fluted roller), and number (N) of seed delivery tubes (at levels of 16, 24, and 32 outlets) on the seed weight delivery coefficient of variation (CV) and seeding rate (SR, kg ha^-1) were investigated. A factorial experiment arranged as a completely randomized design with three replications was used to perform the laboratory experiments. Results showed that the effects of all treatments (n, L, and N) on both SR and CV were significant. The interactions of N×L and L×n were also significant on both SR and CV. The interaction of N×n was significant only on the SR. The interaction of N×L×n was also significant on the SR. Results of mean comparisons revealed that the CV decreased as n and L increased; whereas, it increased as N increased. However, the opposite pattern was observed for the SR with changing the mentioned factors. Minimum SR value (6.1 kg ha^-1 – in the recommended SR range for rapeseed planting) was obtained at 46.5 rpm and L1 (1/6 of the total length of the fluted roller) with 32- outlet seed delivery tube.