Development of 2BZ-2 type fine and small-amount seeder for foxtail millet

Abstract: Foxtail millet is a kind of minor coarse cereal. It is not one of the main grain crops, and is a kind of rainfed crop. So, it is mainly planted in the hilly and mountainous areas in northern China. Foxtail millet is becoming more and more popular in congee because of its mellow taste and abundant nutritional value. Given the characteristics of small and scattered planting plots for foxtail millet in northern hilly and mountainous areas, small seeder is more suitable for this kind of plot. According to the agronomic requirements of fine and small-amount sowing for foxtail millet, we design and manufacture the 2BZ-2 type fine and small-amount seeder for foxtail millet. This seeder consists of 2 sowing units, transmission system, ground wheels and body frame. Every unit is mainly made up of seed-metering device, furrow opener, soil coverer and press wheel. We use the tilt dise-type fine and small-amount seed-metering device for foxtail millet that was designed previously, and its working angle is 45°, and it has 36 filling holes and 36 seeding grooves. This device has got the national invention patent in China, and we have published an academic paper about it on Transactions of the Chinese Society of Agricultural Engineering. We design a kind of ship-shaped shovel type furrow opener, and its penetrating angle is 60°, its soil-cutting angle is 30°, its trenching width is 30 mm, and its height is 100 mm. We design a kind of scraper type soil coverer, and it mainly consists of 2 covering boards, connecting board and pull rod. The covering board is trapezoid-shaped, and its length is 100 mm, its front width is 80 mm, its back width is 40 mm, and its thickness is 3 mm. The included angle between the 2 covering boards is 50°, the inclined angle of the covering board toward the ground is 70°, and the width of the back opening between the 2 covering boards is 30 mm. We push the seeder and provide the driving force. The ground wheels pass the driving force to the seed-metering device via the transmission system. The transmission system is composed of two-stage chain drive and one-stage bevel gear drive. The chain drive uses the 08B roller chains and the matched chain wheels to drive down. The bevel gear drive uses 45° straight bevel gears to realize constant speed drive. According to the experimental requirements of Chinese National Standards, we design and conduct the seeding performance experiments and the field sowing experiments to test the working performance of this seeder. The seeding performance experiments include the tests of the consistency of every row's seeding quantity, the steadiness of total seeding quantity and the percentage of damaged millet. The field sowing experiments include the tests of the uniformity of sowing quantity and the consistency of sowing depth. The results of the seeding performance experiments indicate that, the coefficient of variation of consistency of every row's seeding quantity is less than or equal to 1.10%, the coefficient of variation of steadiness of total seeding quantity is less than or equal to 0.66%, and the percentage of damaged millet is less than or equal to 0.05%. The results of the field sowing experiments indicate that, the qualified index of hill spacing is greater than 83%, the replay index is less than 7%, the miss-seeding index is less than 12%, the coefficient of variation of qualified hill spacing is less than 10%, and the coefficient of variation of sowing depth is less than 1.5%. All the 8 indices meet the requirements of Chinese machinery industry standards. This study can provide a theoretical reference for the design and analysis of the fine and small-amount seeding equipment for foxtail millet suitable for the hilly and mountainous areas.