Design and Experiment of a Helicoidal Seed Tube to Improve Seed Distribution Uniformity of Seed Drills

Abstract

In a conventional seed drill, the flow of seeds into the planting bed is usually disrupted and irregular, which contributes to poor seed spacing uniformity. The seed tube of the seed drill may be one of the reasons for disrupted and irregular seed flow. A seed drill, in principle, has to deposit seeds into the ground at a uniform spacing to avoid nutrient competition for optimum yield. This study was inspired to develop a novel helicoidal seed tube that regulates the flow of seeds in a seed tube while being dispensed by the seed drill into the ground. The helicoidal tube was designed to fit the end of a conventional delivery tube of a seed drill. It works by allowing the falling seeds to move through the helix causing a frictional reaction, thereby regulating the velocity of the falling seeds. The developed helicoidal seed tube was tested under laboratory conditions at three heights of the helix (100, 150, and 200 mm) and four pitch sizes (28, 32, 36, and 40 mm). As a result of the laboratory tests, the optimum values for the helix height and pitch size were determined as 200 mm and 36 mm, respectively. The performance of the helicoidal seed tube (helix height of 200 mm and pitch size of 36 mm) was compared with the conventional (hollow) seed tube under laboratory and field conditions. Trials were carried out at a seeding rate of 200 kg/ha and a forward speed of 1 m/s for both wheat and barley seeds. Field trials showed that the coefficients of variation of seed spacing of the conventional seed tube decreased from 118.4% and 139.5% to 77.2% and 70.6% for wheat and barley sowing, respectively, when the helicoidal seed tube was used. Overall, the use of helicoidal seed tube provided a more equal growing area for each plant due to its lower coefficient of variation.