# Calibration and Analysis of Seeding Parameters of Soaked _Cyperus esculentus_ L. Seeds
## 1 Introduction  
_Cyperus esculentus_ L. is a herbaceous oil seed crop with strong environmental adaptability. It can be planted in barren, marginal, and sandy land, and it has a well-developed root system, offering advantages such as drought resistance, water conservation, wind-break, and sand fixation [1, 2]. _C. esculentus_ seeds are nutritionally rich and can be used for various purposes, such as oil extraction, brewing, food, feed, and pharmaceuticals. _C. esculentus_ boasts a high yield, producing 7.5 to 9.0 tons of dried tubers per hectare, withan oil extraction rate reaching up to 24%. The oil yield per unit area exceeds 1800 kg/hm\({}^{2}\), which is four times that of soybeans and twice that of rapeseed [3]. The \"14 th Five-Year Plan\" for National Planting Industry Development, compiled by the Ministry of Agriculture and Rural Affairs of China, includes _C. esculentus_ as a key variety for the development of oil crops, with its planting area expected to stabilize at about 200,000 mu by 2025 [4]. However, at present, the mechanization technology for _C. esculentus_ planting is still underdeveloped, and there is a shortage of effective _C. esculentus_ machinery, particularly in the area of precision sowing technology, which limits the potential for enhancing both the yield and quality of _C. esculentus_. To develop an air-suction-type precision seeder for _C. esculentus_ seeds, it is necessary to measure the characteristic parameters of the seeds and the contact parameters between the seeds and the seeder. However, the uneven and irregular shape of _C. esculentus_ seeds makes it difficult for them to be effectively adsorbed by the seeder, which significantly affects the precision seeding performance. Therefore, soaking the seeds before sowing helps to expand and round their surfaces, improving the seed shape parameters and facilitating effective adsorption during precision seeding. Additionally, soaking activates dormant seeds, enhancing germination rates. However, the characteristic parameters of the seeds change significantly after soaking, making it necessary to accurately measure the intrinsic parameters of soaked _C. esculentus_ seeds and the contact parameters between the seeds and the seeder. This will provide the necessary parameter support for the analysis of the precision seeding of soaked _C. esculentus_ seeds. The seeder is a core component in the planting of _C. esculentus_ seeds, and the performance of seed filling and discharge is a crucial step in improving efficiency. Traditional optimization processes often fail to account for the contact and motion of _C. esculentus_ seed particles with mechanical components during sowing, making it difficult to achieve the desired optimization goals. The discrete element method, a specialized numerical analysis method for multi-particle systems, has applications across industries such as agriculture and mining. The sowing process of _C. esculentus_ seeds involves classic interactions between particles and mechanical components, making it feasible to conduct calibration simulation experiments using EDEM [5; 6; 7; 8]. A linear function between the zero-level value and the measured value during factor calibration for two key factors--the interspecies static friction factor and the rolling friction factor--of the maize grain bonding model was established, demonstrating that the calibrated contact parameters of the maize discrete elements were plausible [9]. Parameter calibration tests on corn stover-cow dung blends were conducted, using a combination of simulation analysis and physical tests to verify the accuracy of the calibration parameters. The results of the study provide a reference for the discrete element simulation of the compression molding of corn stover-cow dung blends [10]. Parameter calibration tests on potato seeds were also conducted, with the results showing that the simulated particle stacking angle of the calibrated miniature potatoes and the seed distribution matched the real test conditions [11].