Hu Liu

The mechanized transplanting of sweet potato slips onto mulched raised beds in China’s Huang-Huai-Hai region faces significant challenges due to fragmented smallholder farms and the specific agronomic requirement of “boat-shaped” horizontal planting. To address this gap, this study aimed to develop a compact, cost-effective transplanter that meets the “boat-shaped” planting agronomy and adapts to small plots. We designed the 2CGX-1 mini wheel-driven transplanter coupled with a tractor. This machine features a compact chassis ( ¥800/ha), this transplanter achieves a daily operational efficiency of ~0.35 ha/day (calculated by 0.55 km/h speed × 0.8 m working width × 8 h daily working time). Meanwhile, the consistency of its key planting indicators and the planting qualification rate are significantly superior to those of manual planting, while improving operational quality and significantly reducing labor cost input. Deviations in individual indicators mainly stem from planting positioning deviations induced by terrain undulations in hilly test areas, and sweet potato seedlings’ tendency to fall off during clamping due to mechanical vibration. However, these errors are within the acceptable agricultural operation range and do not compromise the machine’s overall compliance with agronomic requirements. The transplanter effectively meets agronomic requirements while offering a cost-effective, adapted solution for small-scale sweet potato production systems, significantly advancing mechanization capabilities for mulched cultivation.

Pneumatic wheat seed-metering device often has a poor seed-filling state under the high-speed working condition, which adversely affects precision seeding. This paper describes a wheat seed-metering device that employs a combined mechanical-pneumatic seed-filling method. The orifice structure and seed-filling space at the nozzle are optimized to improve the seed-filling efficiency and seed-carrying stability. The working process of the wheat seed-metering device was analyzed, the principles of the seed-filling and seed-cleaning processes were elucidated, the factors influencing the seed-filling performance and seed-carrying stability were investigated, and the discrete element method-computational fluid dynamics (DEM-CFD) simulation method was employed to simulate the working process. The nozzle-orifice diameter, seed-filling-space angle, and rotation speed were determined as the simulation influence factors, and the trends of the nozzle void fraction, resistance to clearing, and initial dropping position were analyzed from a microscopic scale. On a macroscopic scale, the seedleakage rate, reseeding rate, and grain-spacing qualification rate as performance-evaluation metrics were analyzed, and the significant order of impacts for these influencing factors and their interaction effects was obtained. Through secondary optimization experiments, the optimal parameter combination was determined to be a nozzle-orifice diameter of 1.7 mm, a seedfilling-space angle of 39.3°, and a rotation speed of 657.4 r/min. Static bench-validation tests and indoor vibration-environment simulation experiments were conducted, and the results were compared with a control group. The findings reveal that when the seed-metering plate rotation speed varies between 400 r/min and 1000 r/min, the optimized seed-metering plate exhibits a seedleakage rate below 7.6% and superior performance in all indicators compared to the original seed-metering plate, indicating a significant improvement in seed-filling efficiency and seed-carrying stability.

The sweet potato transplanters of diverse transplanting configurations have been shown to produce various planting properties in relation to different raised bed cropping systems, thus affecting crop growth and yield in sweet potato cultivation. In Shandong Province, a field experiment assessed the effects of three treatments (RB1, mulched raised beds with a finger-clip type transplanter; RB2, bare raised beds with a finger-clip type transplanter; and RB3, bare raised beds with a clamping-plate type transplanter) on soil temperature, plant growth, yield, and economic benefits. With the lowest coefficient variation of plant spacing and planting depth, the RB1 with the finger-clip type transplanter had 6.4% and 6.0% higher temperature at 5–10 cm soil layer by using the plastic-mulch for rapid early slips growth as compared with the RB2 and the RB3, respectively. Consequently, the leaf area index in the RB1 was increased by 5.6% and 6.4% as compared to the RB2 and the RB3, separately. This finally contributed to 57.5–70.8% greater fresh vines weight and 23.8–33.8% higher tubers yield in the RB1 compared with both the RB2 and the RB3 treatments, respectively. In general, in the mulched raised bed system of the Huang-Huai-Hai region of China, the finger-clip type transplanter could be a suitable option for the transplanting of sweet potato slips. In the bare raised bed system, meanwhile, the clamping-plate type transplanter has the potential to increase the production of sweet potatoes.

China is the largest vegetable producer in the world, and vegetable production is more geographically concentrated in the Huang-Huai-Hai region and the Yangtze River Basin. There are significant challenges ahead for increasing the average yields of the vegetables in this region. The effects of a cultivation system, a mulched ridge with a double row (MRDR), were evaluated by using the 2ZBX-2A vegetable transplanter newly designed in this paper. The key parameters of the equipment were designed and optimized by using the human–computer interaction method and the discrete element method according to agronomy requirements. Compared with the traditional ridge (TR) system on two typical solanaceous vegetables (eggplant and capsicum), the uniformities of the plant spacing and the planting depth in the MRDR system were significantly improved. Finally, the fresh fruit yield in the MRDR system increased significantly (p < 0.05) by 40.8% and 35.3% compared with that in the TR system for eggplant and capsicum, respectively. In addition, the water use efficiency (WUE) was also 54.9~59.7% higher under the MRDR system than under the TR system. All the results indicate that the MRDR system has the potential to improve the yields and WUE of solanaceous vegetables in the Huang-Huai-Hai Plain of China.

China is the world’s biggest producer of sweet potato (Ipomoea batatas (L). Lam.), and approximately 55% of the global supply is from China. Raised beds (RB) and raised beds mulched with plastic film (RBF) are the two main sweet potato cultivation systems now widely used in northern China. Planting placement of multiple nodes buried in shallow soil layers is additionally required for the sweet potato cultivation to achieve higher yields and reduce pests and diseases in this area, which increases the difficulty of transplanting mechanically. Therefore, a 2CGFS-2 compound sweet potato transplanter was developed, and the key parameters of slips transplanting apparatus were designed in this paper. Furthermore, its performance was investigated over two years under four treatments with different sweet potato varieties (Jishu 26 and Pushu 32) and cultivation systems (RBF and RB). The results showed that the missing seedling rate and qualified rate of transplanting population for each treatment by using 2CGFS-2 compound transplanter were 95.0% in both 2020 and 2021, while the mean values of the plant spacing variation coefficient and the qualified rate of transplanting depth during 2020–2021 were 4.53% and 96.28%, respectively. The length of the sweet potato slip inserted into the soil by the 2CGFS-2 compound sweet potato transplanter was almost the same, ca. 195 mm. The accurate placement of the sweet potato slips reduced the differences in tuber weight per plant caused by manual transplanting. These results are of considerable importance for RB and RBF sweet potato cultivation systems.

In Huang-Huai-Hai plain of China, farmers collect the maize straw for livestock during maize harvest to increase their revenue. To maintain the sustainable productivity of the soil, all straw after the wheat harvest is returned to the field. This straw brings difficulties in the no-till seeding for maize after wheat harvest, and thus it is necessary to develop efficient no-till seeders that can cope with heavy residue and improve sowing quality. In this work, we designed a wide-strip-till no-till pneumatic maize (WNPM) seeder to satisfy the need in this plain. The key parameters of the opposite-placed anti-blocking mechanism of the WNPM seeder were determined via the discrete element method (DEM) technology, while the parameters of the pneumatic maize seed meter were specified using the coupled simulation of computational fluid dynamics (CFD) and DEM. We also carried out field experiment to test the performance of our machine. Under the operating speed of 8 km/h, the soil disturbance was 38.2%. Moreover, the straw cleaning rate achieved 94.4% in the seeding belt while the residue cover index of the seed plot was over 58%, and the seeding performance was improved significantly. The qualified seed spacing index, uniformity variation coefficient, qualified index of sowing depth and variation coefficient of sowing depth were 96.6%, 19.1%, 95.1% and 3.2%, respectively. In general, the WNPM seeder improves the working efficiency of maize sowing because both the reliable working speed and the sowing quality were increased. These results are of considerable importance for crop production in Huang-Huai-Hai plain of China.