# Research on Seeding Performance of Self-Propelled Industrial Hemp Seeder
## 1 Introduction  
Industrial hemp is an annual non-toxic herbaceous plant belonging to Cannabaceae. It has no psychoactive and drug utilization value with a THC (tetrahydrocannabinol) content of less than 0.3%. Industrial hemp is rich in nutrients with high economic use value. It is mainly divided into fiber type, seed type, and medicinal type by usage, and is widely used in textile, food, medicine, health, daily chemical, and other fields [1, 2]. According to statistics from China's Bureau of Statistics and the Food and Agriculture Organization of the United Nations, China has the world's largest industrial hemp cultivation area, accounting for about 50% of the world's total industrial hemp cultivation area. The industrial hemp industry is controlled by strict laws in China, and its legal cultivation area is mainly located in the Yunnan and Heilongjiang provinces of China. The mechanized planting area of industrial hemp is principally divided into the plain with vast territory and large seeding area, and the hills and mountains with little cultivated land and scattered seeding plots. The plain generally utilizes large-scale seeders or coating film seeders for work [3, 4]. The hills and mountains generally utilize small and medium-sized seeders for work. Nevertheless, due to the lack of specialist industrial hemp seeders for fiber use, the planting of industrial hemp for use in fiber in hilly areas is still predominantly manual or semi-mechanical, as there is a lack of professional joint seeders for industrial hemp. The fibrous industrial hemp in the mountains and hills area is suitable for dwarf dense planting, and the main planting type is stripe sowing, with a total seeding quantity of 57.6-62.4 kg/hm\({}^{2}\), row spacing of 150-250 mm, and sowing depth of 30-80 mm. The existing industrial hemp seederis mainly suspended, with large width and large turning radius. Consequently, it is not suitable for hilly and mountain operations, and the total seeding quantity does not meet the agronomic requirements [3; 4; 5]. Seeders are not only an essential element of the mechanized planting of industrial hemp but also an inevitable way to propel the production efficiency of industrial hemp [6; 7]. It is urgent to develop a self-propelled seeder suitable for planting fiber industrial hemp in mountains and hills areas. The seed metering device is the core part of the seeder. An efficient and reliable seeder is the key to ensuring the working quality and efficiency of the seeder [8; 9; 10]. According to the working principle, the seed metering device is divided into mechanical and pneumatic types [11; 12; 13]. Pneumatic seed metering devices have good adaptability to seeds, high precision of single seed metering, and low seed damage rate. Nevertheless, its complex structure, high energy consumption, and easy sealing can be affected by machine vibration, leading to strict requirements for the working environment. The mechanical seed metering device has the advantages of simple structures, strong versatility, and easy to achieve dense seeding [14; 15; 16], which has become the first choice for mechanized seeding of hemp for the fiber industry in hilly and mountainous areas. The fiber industrial hemp shape ellipse, small particle size, lightweight, researchers worldwide have conducted numerous studies on small size seed metering devices. For instance, [PERSON] et al. [17] designed a central roller seed arrangement device to address the common problems of high damage rate and low seeding accuracy in the rice seeding process, researched the influence of roller speed on seed arrangement performance, and improved the applicability to different seeds by replacing rollers with shaped holes. To meet the requirements of high speed and precision seeding of corn seeder, according to the material characteristics of flat corn seeds, [PERSON] et al. [18] designed a horizontal disc metering device with an inclined longitudinal rectangular hole to make the metering plate.