Aiming at the problems of poor passability of a tracked chassis due to small plots, complicated road conditions and steep slopes during mechanized potato harvesting in hilly and mountainous areas. To design a potato combine harvester and take the tracked chassis of the harvester as the research object to study its driving performance under typical road conditions in mountainous areas. Firstly, mechanical analysis and theoretical calculation are carried out on the tracked chassis to obtain the relevant parameters of key components, and secondly, its driving performance is analyzed to obtain the driving limit values of passing performance under different working conditions; RecurDyn software was used to establish the dynamics simulation and analysis model of the whole machine, and the driving limit values of the harvester were determined under five different road conditions through simulation. The results show the following: the driving limit gradient angle is 20° in cross-gradient conditions, 25° in longitudinal up-gradient conditions, 25° in longitudinal down-gradient conditions, the limiting height of the chassis that can be overpassed in obstacle-crossing conditions is 450 mm, and the limiting width of the chassis that can be spanned in trench-crossing conditions is 1200 mm. The simulation results were verified through field tests, and the results of the field tests showed that the harvester met the requirements of stable travelling on longitudinal slopes of 24°, climbed over a 450 mm straight wall and crossed over a 1200 mm trench, which were similar to the simulation results, indicating that the simulation results were accurate and feasible, and met the design requirements for the travelling passage of the crawler potato harvester. This study provides an in-depth understanding of the tracked chassis of the potato combine harvester in hilly mountainous areas, with a view to providing reference for the design of tracked harvesters for other crops in hilly mountainous areas.

The strip mulch of corn straw planting technique is widely used in the Northwest rain-fed agricultural region of China due to the region’s good soil moisture-temperature properties. However, the hydrothermal properties and yield effects of this planting technique on different potato varieties are not clear. Therefore, a field experiment was conducted for two years (2015 and 2016) in the rain-fed area of Northwest China, to study the effects of different mulching treatments on the yield and water use efficiency (WUE) of potato with different maturation characteristics (potato varieties Longshu 7 and LK99). A split-plot experimental design was used. The experiment included corn straw strip flat cover planting (SMF), plastic film mulching (PMF), corn straw strip ditch mulching and ridge planting (SMFR), straw flat fully covered (SMWF), and uncovered and flat planting (CK). The results showed that straw mulch and plastic film mulch had significant effects on yield and WUE (p < 0.05). Compared with CK, SMF significantly increased the yield by 3.75–63.17% in the late-maturing varieties, and increased the yield by 24.96–79.02% in the early-maturing varieties. Among the mulching treatments, compared with SMF, PMF made no significant difference in the yield and WUE between the late-maturing varieties in the normal year and the early-maturing varieties in the dry year, but the yield and WUE of the early-maturing varieties in the normal year significantly decreased by 17.25% and 18.44%, respectively, and the yield and WUE of the late-maturing varieties in the dry year significantly increased by 27.57% and 29.26% respectively. Compared with SMF, SMFR reduced yield by 1.44–13.62%; SMWF decreased the yield of late-maturing varieties by 25.94% (p < 0.05), and WUE decreased by 7.65–23.44% (p < 0.05). It can be seen that under this experimental condition, SMF is more suitable for early-maturing varieties and PMF is more suitable for late-maturing varieties.

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.

Plastic film mulching is one of the key technologies for improving agricultural productivity in arid and semi-arid regions. However, residual plastic film can severely disrupt the structure of the topsoil in farmland, leading to a decrease in crop yield. The Hexi Corridor, as the largest seed maize production base in the arid regions of Northwest China, is facing an increasingly prominent issue of residual plastic film recovery. This study designed experiments based on the typical maize planting model in the Hexi Corridor. A discrete element simulation model of the residual film–soil–root stubble complex was established using the Bonding-V2 model and API rapid filling technology. The reliability of the simulation model was verified through shear and puncture tests. The study revealed that the soil type in the Hexi Corridor is heavy sandy soil. The differences between the average maximum shear forces in the simulated and actual shear tests for root stubble–soil complexes at depths of 30 mm, 50 mm, and 100 mm were 4.8%, 6.4%, and 6.5%, respectively. Additionally, the differences in the average maximum vertical loading forces in the simulated and actual puncture tests for root stubble–soil complexes at depths of 50 mm and 100 mm were 6.4% and 12.37%, respectively. The small discrepancies between the simulated and actual values, along with the consistency of particle movement trends with real-world conditions, confirmed the reliability and accuracy of the simulation model. This indicates that the established discrete element flexible model can effectively represent actual field conditions, providing discrete element model parameters and theoretical support for optimizing the design of key components in China’s mechanized root stubble handling and residual film recovery machinery.

To address the issues of the poor filling and clearing efficiency of spoon–chain potato seed dischargers, an optimization design was implemented in this study. Based on the motion characteristics of potatoes during the filling and transport processes, an inclination angle was set for the seed spoon cavity, and a seed-clearing brush was installed at the top of the seed discharger. A DEM-MBD coupled simulation model of the seed discharger was constructed. The working speed of the driving sprocket, the inclination angle of the seed spoon cavity, and the seed holding height were used as experimental factors, while the single-seed qualification rate, missed seed rate, and over-seeding rate were used as evaluation indices to conduct a quadratic regression orthogonal rotation combination experiment. This determined the optimal technical parameter combination for the best working performance. Based on the results of the DEM-MBD coupled simulation experiments, a response surface optimization test was conducted. The results showed that the optimal working performance was achieved when the working speed of the driving sprocket was 43 rpm, the inclination angle of the seed spoon cavity was 15°, and the seed holding height was 0.2 m. Under these conditions, the single-seed qualification rate was 95.28%, the missed seed rate was 0.92%, and the over-seeding rate was 3.80%. Further soil bin tests confirmed that, under the optimal working parameters, the relative deviations of all test indices from the response surface optimization test results were less than 2%. The research results provide new insights for the optimization design of spoon–chain potato seed-metering devices.