Design and experiment of soil covering and compacting device for Panax notoginseng seedling sowing

Objective  Aiming at the special agronomy of small row spacing and shallow sowing depth of slot type Panax notoginseng seedling, a compact soil covering and compacting device for seed ditch was designed to improve the quality of P. notoginseng seedlings.

Method  On the basis of the field experiment to determine the range of matrix compactness with high emergence rate and the best seedling grade of P. notoginseng, the dynamic analysis of the contact between roller and soil was carried out to determine the relevant parameters of the soil covering and compacting device. The process of soil covering and compacting was simulated and analyzed using discrete element method. Taking ditching depth and forward speed of the planter as test factors, the covering soil thickness and consistency as the test indexes, soil trough test was carried out to verify whether the relevant structural parameters of soil covering and compacting device met the requirements.

Result  The results of field experiment showed that the range of substrate compactness was 200 to 400 kPa. The structural parameters of the soil covering and compacting device were as follows: The diameter of the pressing wheel was 150 mm, and the maximum spring stiffness was 140.5 N/mm. The simulation results showed that the soil covering thickness was 9.77 to 11.40 mm, the offset of grain spacing was 0.07 to 6.23 mm, and the offset of row spacing was 0.03 to 1.43 mm.The results of soil trough test showed that the optimal working parameters were as following: The trench depth was 25 mm, the forward speed of planter was 0.16 m/s, the average covering thickness was 11 mm, the consistency of soil covering thickness was 85.15%, and the compactness of substrate after compaction was 300 to 360 kPa.

Conclusion  According to the simulation analysis and soil trough test, the design of the soil covering and compacting device can meet the agronomic requirements of substrate compactness and covering soil thickness for P. notoginseng seedlings. The research results can provide references for the design of soil covering and compacting device of P. notoginseng.