Aiming to solve the problems of easy generation of clods, poor soil fluidity and poor soil-covering effect in the no-tillage seeding operation mode, this study has designed a soil-covering device with a soil-closing function for the chisel-type furrow opener of a corn no-tillage planter. Theoretical analysis and design of the soil dividing plate and the soil-covering disc were carried out, and the key parameters were determined. Then, the soil-covering device with soil-closing function and the soil movement model was constructed in Altair EDEM, and the spatial soil particle mobility was analyzed. The numerical simulation method was combined with the center plane composite response test scheme to carry out the simulation test, and the optimal working parameter combination was obtained. The operating speed was 6.35 km·h⁻¹, the inclination angle of the soil-covering disc was 60°, the opening angle of the soil-covering disc was 70°, and the inclination angle of the soil dividing plate was 40°. A comparative test of the soil-covering effect and performance was carried out, and the results showed that the designed device was better than the traditional soil-covering device in terms of the consistency of soil-covering thickness and the stability of seed position deviation. The relative errors of the soil bin experiment results and the simulation optimization results for the cover soil thickness and seed position deviation were 5.7% and 11.1%, respectively. The operation effect of the designed soil-covering device with soil-closing function meets the requirements of soil covering under no-tillage conditions and provides a basis for the research and development of soil-covering suppression technology and devices under no-tillage seeding mode.

Wheat sowing has the characteristics of wide and short sowing periods, and there are situations in which the suitable sowing period is missed. In order to meet the needs of high-speed sowing, a centrifugal wheat strip seeding device was designed, the principle of which is that rotating parts were mainly composed of centrifugal concave plate and guide strip rotating in the shell to provide the mechanical force and drive the airflow and then realize high-speed seeding. The influence of the rotational speed of the seed discharging plate, the seed feed rate, and the dip angle of the guide strip on the distribution of the flow field and trajectory of seeds in the device was analyzed. The aerodynamic characteristics of seeds and the distribution of the gas-phase flow field inside the seed displacer under airflow were analyzed by CFD–DEM coupled simulation. The effects of three operating parameters on the coefficient of variation of sowing uniformity (CVSU) and the row-to-row seeding amount coefficient of variation (RSCV) were clarified, and the simulation results were verified by bench experiments after secondary optimization. When the centrifugal concave plate rotational speed, seed feed rate, and guide strip angle were 408 rpm, 4938 grains/s, and 69°, the results showed that CVSU and RSCV were 1.12% and 2.39%, respectively, which was in line with the standards for grain strip seeders stipulated. The designed seed discharge device can sow 3.4 ha per hour. This study provides a reference for research of centrifugal airflow-assisted high-speed seeding devices for wheat.