A self-propelled machine for combined potato harvesting and residual plastic film retrieval is presented in this paper. The machine was designed collaboratively and built at the College of Mechano-Electronic Engineering of Gansu Agricultural University. It is intended for slow slope and horizontal terraces in hilly and mountainous areas of Northwest China, where regular-size harvesters cannot operate. The machine can realize the combined operations of potato digging, potato separation from soil and plastic film, potato collection and bagging, and residual plastic film retrieval. Through engineering analyses, the main systems of the machine were calculated, and their operating parameters were estimated. These include the digging and lifting device, the potato–plastic-film separation device, and the residual plastic film retrieval device. Field tests were performed at a 0.5 m/s driving speed of the machine, while the linear speed of the lifting chain of the digging and lifting device was 1.5 m/s, the tilting angle of the conveying chain of the potato and plastic film separation device was 50°, its linear speed was 0.6 m/s, and the linear speed of the lifting screen of the circulating lifting device was 0.7 m/s. With these settings, the average productivity of the machine was 0.12 ha/h. The loss rate, damage rate, and potato bruising rate were 1.8%, 1.4%, and 2.8%, respectively; the potato impurity rate was 3.6%; and the residual plastic film retrieval rate was 83%—all above industry standards. This research provides a solution to the problem of mechanized potato harvesting and plastic mulch retrieval on small, slopped plots of land in Northwest China and in other parts of the world where similar conditions exist.

The mechanized harvesting level of potatoes in the arid areas of Northwest China is low and mainly relies on simple machinery to dig the soil surface, and then people manually pick up and bag the potatoes. This harvesting method has the problems of a high labor intensity, low operation efficiency, and high labor cost. Based on this, a wheeled-chassis potato combine harvester with integrated bagging and ton bag-lifting systems was developed, which could complete potato digging, potato–soil separation, potato–film separation, automatic bagging, and field ton bag lifting in one go. Firstly, based on the agronomic requirements and unique terrain characteristics of potato planting in this area, the structural design of the whole machine was completed with SOLIDORKS 2019 3D software. Secondly, the dynamic model was established for a numerical analysis, and the core parameters of key components were determined. The field experiments showed that the potato loss rate was 2.1%, the potato damage rate was 1.7%, the skin breaking rate was 2.5%, the impurity content was 1.9%, and the productivity was 0.15~0.23 hm²/h. The above field test indexes met the requirements of national and industrial standards.

This paper presents the designs and calculations of a leaping type soil-covering device for potato cultivation. The device is based on the full-film mulching cultivation mode, where the seed rows are covered with soil. The working principle of the leaping type soil-covering device was analyzed and the core structural parameters were determined. In order to search for a reasonable rotation speed of the screw conveyor, the soil-covering process of leaping type soil-covering device is simulated based on the EDEM software. Through single factor simulation experiments, relationship between the width and thickness of covering soil and the rotation speed of the screw conveyor was studied. The optimal values obtained were the scraper height of 60 mm and the screw conveyor rotation speed of 169 r/min. Based on the quadratic function fitting, the relationship between the length of the soil cover and the position of the seedling belt was determined. With the optimization objective of the seedling belt misalignment rate, the length of the soil cover was determined to be 417 mm. A prototype of the device was manufactured and tested in the field. The field test showed that the qualified rate of the thickness of the seeded soil cover was 92%, the qualified rate of covering soil thickness was 91%, the dislocation rate between the seeding row with covering soil and the seedling belt was 5%, and the damage degree of plastic film was 49.2 mm/m². These results indicate that the designed potato planter with leaping type soil-covering device meets accepted agronomical requirements of potato planters and film-mulching planters. The natural emergence rate of potato seedlings reached 92% and the seedling burning rate was 7%.

In response to the problem of no supporting equipment for the cultivation of Codonopsis in the hilly and mountainous areas of northwest China, a combined machine for transplanting outcrop of Codonopsis with micro ridges covered with film is designed. The key components of the prototype are analyzed and designed, and the structures and working parameters of the seedbed preparation device, seedling-casting device, rotary tillage soil-covering device, film-covering device, seedling head burial, and film edge soil-covering device are determined. The transmission system scheme is established, and the working mechanism of the core components is analyzed. Field experiments show that when the target seedling spacing is 4.4 cm and the machine moves forward at a speed of 0.1, 0.15, and 0.2 m/s, the variation coefficient of planting spacing and the qualification rate of planting depth meet the standard requirements. The qualified rate of planting posture and film side outcrop are greatly affected by the operating speed of the machine and decrease with the increase in operating speed. When the operating speed reaches 0.1 m/s, the average variation coefficient of planting spacing is 0.08% and the average qualified rate of planting depth, planting posture and film side outcrop is 95.83%, 94.17%, and 93.33%, respectively, which shows that the operating performance is better than that of the operating speeds of 0.15 m/s and 0.2 m/s. This study provides a new reference for the theoretical research and design of mechanized and automated transplanting machinery for Codonopsis seedlings.

To address the challenges of labor-intensive, inefficient, and inconsistent manual hole sowing and transplanting of Angelica sinensis in rain-fed hilly regions of Northwest China, a pneumatic hole-sowing device was designed based on the principle of electromagnetically controlled, high-speed reciprocating cylinder motion. Considering the agronomic requirements for transplanting mulched Angelica sinensis, the device’s structure and operational parameters were optimized. The key mechanisms involved in hole sowing and seedling placement were analyzed. A pneumatic circuit system, controlled by a relay circuit, was established, and a hole-sowing mechanism with a delayed closure effect was designed. Using the Discrete Element Method (DEM) and Multi-Body Dynamics (MBD) coupling technology, a simulation of the hole-sowing process was conducted to evaluate the device’s performance and its impact on soil disturbance and hole reformation in the seedbed. Prototype device performance tests were conducted, using qualified seeding depth under mulch and hole spacing as indicators. When the theoretical hole spacing was 30 cm and the hole-sowing frequency was 60 plants/(min·row), the soil bin test results indicated a seeding depth qualification rate of 93%, a misalignment rate of 3%, and a spacing qualification rate of 83%; the field test results showed a qualified seeding depth rate under mulch of 96%, the hole misalignment rate was 5%, and the spacing qualified rate was 86%. The pneumatic hole-sowing device’s performance meets the agronomic requirements for vertical transplanting of Angelica sinensis seedlings. This research can serve as a reference for designing planting machinery for rhizomatous medicinal plants.

In response to the problem of no supporting equipment for the cultivation of Codonopsis in the hilly and mountainous areas of northwest China, a combined machine for transplanting outcrop of Codonopsis with micro ridge covered with film is designed. The key components of the prototype are analyzed and designed, and the structures and working parameters of the seedbed preparation device, seedling casting device, rotary tillage soil-covering device, film covering device, seedling head burial and film edge soil-covering device are determined. The transmission system scheme is established, and the working mechanism of the core components is analyzed. Field experiments show that when the target seedling spacing is 4.4cm and the machines moves forward at the speed of 0.1, 0.15, and 0.2m/s, the variation coefficient of planting spacing and the qualification rate of planting depth all meet the standard requirements. The qualified rate of planting posture and film side outcrop are greatly affected by the operating speed of the machine, and decrease with the increase of operating speed. When the operating speed reaches 0.1m/s, the average variation coefficient of planting spacing is 0.08%, the average qualified rate of planting depth, planting posture and film side outcrop is 95.83%, 94.17% and 93.33% respectively, which shows that the operating performance is better than that of the operating speed of 0.15m/s and 0.2m/s. This study provides new reference for the theoretical research and design of mechanized and automated transplanting machinery for Codonopsis seedlings.