Evaluation of Seed Distribution Uniformity of a Multi-flight Auger as a Grain Drill Metering Device

The study of fluted-roller seed meter, the commonly used feeding device on grain drills, revealed that the seed metering uniformity is impaired due to sudden release of seed batches. The use of multi-flight screws (augers) as a seed metering and feeding device for grain drills was studied. As preliminary test, 12 multi-flight auger configurations were designed and evaluated for seed spacing at three travel speeds. The uniformity of seed distribution was evaluated by a laboratory method using the coefficient of uniformity. The different auger configurations studied are the auger groove depth and width, number of flights, auger outer diameter and rotational speed.Results indicated that different auger characteristics have significant effects on seed uniformity discharge from the feed units. In general, the uniformity tended to increase with increasing auger outer diameter, depth and width of grooves, number of auger flights and rotational speed. Based on the results of the preliminary test, two extra augers were designed and developed. The first auger was 50 mm in diameter with seven flights and a 10 mm groove depth and width (A5), while the second one was 70 mm in diameter with seven flights and a 14 mm groove depth and width (B5). The performance of these augers was evaluated and compared to that of fluted-roller feed device. The coefficient of uniformity was calculated at three different travel speeds of 2·86, 4·78, and 6·61 km h−1. The coefficient of uniformity of augers was mostly higher than those for the fluted-roller metering device. The auger coefficient of uniformity was significantly higher than those for the fluted-roller meter at lower speeds. However, there was not any significant difference at higher speeds between the feed units tested. The coefficient of uniformity, over all speeds, for the fluted-roller, auger A5 and auger B5 were 0·89, 0·91 and 0·92, respectively.