Pneumatic centralized seed metering has been developing rapidly in China, due to its high precision, efficiency, and low seed damage. However, the traditional centralized wheat metering devices are often equipped with a straight groove wheel. Once the amount of the seed discharged is high, the groove wheel can rotate to the groove and low at the ridge, thus resulting in the pulsation during seeding. The discharge stability and uneven seed distribution can be caused by the pulsation of the straight groove wheel. This study aims to propose a precision centralized wheat metering device with a staggered helical groove wheel. According to the seed metering device with the outer groove wheel, the seed metering was optimized to eliminate the seed-feeding layer for the low inter-seed stress and seed damage. The helical structure was provided to enhance the uniform seeding. Two groove wheels with helical grooves were arranged in a staggered configuration. Among them, the two wheels were allowed to discharge the seeds in a complementary manner. The seed flows of the two groove wheels complemented each other, particularly for the phase complementarity of the seed supply cycle with the dual helical groove wheel. The pulsation was further reduced for the uniform seed discharge and stable seed rate. According to the seed stress between teeth and seed population motion, the helical angle and stagger angle were the key influencing parameters on the discharge stability and seeding uniformity. The working parameters of the centralized seed metering device were determined to calculate the seed-holding space of the helical groove wheels. A two-factor and multi-level simulation was conducted using the Discrete Element method (DEM), with the helical angle and stagger angle as the experimental factors, while the discharge stability and seed distribution uniformity as the evaluation indices. The optimal combination of the parameters was identified after optimization. The results showed that both the helical angle and stagger angle shared significant effects on the discharge stability and seed distribution uniformity (P ＜0.05). The coefficients of variation for both discharge stability and uniformity first decreased and then increased with the increasing helical angle, while they gradually decreased with the increasing stagger angle. The best performance was achieved when the helical and stagger angles were 45° and 20°, respectively, with the coefficients of variation of 2.06% and 7.29%, respectively. Bench test results showed that the performance of the centralized seed metering device was only slightly affected by the operating speed. The coefficients of variation for the discharge stability, the seed distribution uniformity, and the seed damage rate were below 2.23%, 7.52% and 0.056%, respectively, when operating at 8-10 km/h. Compared with the traditional outer groove wheel, the average coefficients of variation for the discharge stability and seed distribution uniformity, and the seed damage rate were reduced by 10.14, 4.5, and 0.093 percentage points, respectively. Furthermore, the inter-groove seed stress of the helical groove wheel was significantly lower, where the peak stress was reduced by about 50 percent. The seed stress was reduced across different groove wheels and seeding stages, leading to the low seed damage of the helical groove wheels. There was some impact of the staggered helical groove wheels on the performance of the centralized wheat metering devices. The finding can also provide the theoretical support for the operational stability and uniformity in the groove wheel-type conveying devices during agricultural production.

In view of the problems existing in the combined harvest of potatoes in China, such as short harvest period and the traditional mechanical cleaning methods that rely heavily on mechanical excitation for the separation of potato impurities, resulting in low efficiency, high skin breaking rate, and frequent mechanical failures caused by films and vines entanglement, this study proposes a non-contact pneumatic flexible potato cleaning technology. Traditional mechanical cleaning equipment mainly relies on physical contact sorting, which is difficult to handle the residual plastic films and vines during the mechanical harvesting process, intensifying the difficulty of manual cleaning and causing skin damage. Although the remaining films are usually processed by dedicated film recovery machines, long-term weathering can leave broken films in the soil, which are accidentally harvested along with the tubers, thereby intensifying the challenge of separation. Inspired by the wide application of pneumatic cleaning in crops such as rapeseed, corn and soybeans, this study designed a pneumatic vines and residual films removal device for potato machines, which is used after harvest and before storage. The main structure and working principle of the device were introduced in detail. The kinetic analysis of the materials entering the separation chamber and during the throwing process of the vibrating screen was carried out, and the lifting trajectory of the residual films was simulated to determine the key parameters affecting potato skin breakage rate and cleanliness rate. Under the condition of airflow velocity of 35 m/s, CFD simulation was carried out for the flow field at different height sections above the screen surface. CFD-DEM coupling simulation experiments were conducted under the conditions of feeding amount of 20 t/h, airflow velocity of 35 m/s, and vibration frequency of 5 Hz, and the simulation test results of 1.2, 3.8, and 6.0 s were analyzed. The coupling effects of vibration frequency and airflow at different velocity on the material lifting trajectory, stratification efficiency and demolding performance were studied. Taking the cleanliness rate and skin breaking rate as evaluation indicators, the parameter combination was optimized through single-factor and L9 (3⁴) orthogonal tests. Orthogonal experiments show that the primary and secondary factors affecting the cleanliness rate are airflow velocity, vibration frequency and feeding volume in sequence, while the order affecting the skin breaking rate is vibration frequency, feeding volume and airflow velocity in sequence. Under the conditions of a feeding rate of 20 t/h, a vibration frequency of 5 Hz, and an airflow velocity of 35 m/s, the cleanliness rate was 97.2% and the skin breakage rate was 0.98%. These results provide crucial technical support for the development of non-contact pneumatic flexible cleaning technology for potatoes, especially in optimizing the gas-solid two-phase flow dynamics of large irregular agricultural materials while minimizing mechanical damage. Meanwhile, the application of research methods such as CFD airflow and flow field simulation technology in production practice has promoted the application and development of computer measurement and control technology in agricultural mechanization and intelligence.

While straw mulching has been recognized for mitigating compaction, the multifactorial effects of straw parameters (content, length, laying modes) under static versus dynamic loads remain poorly quantified. Straw mulching may alter the stress transfer in the soil when applying static or dynamic loads. This study systematically evaluated stress and energy dissipation mechanisms using laboratory simulations: a plate sinkage test and an adapted Proctor test. The results demonstrated that the straw content (0-20 Mg/hm²) dominantly governs dissipation efficiency, with maximum stress dissipation ratios of 45.6% (static load >200 kPa) and energy dissipation ratios of 38.64% (dynamic high-energy). Longer straw (0.20 m) and ordered laying modes enhanced stress dispersion only under low static loads, while dynamic loads exhibited weaker dissipation. The study reveals that the damping effect of straw is strongest under low stress static load, so it is necessary to reduce the compaction of agricultural machinery and optimize the allocation of straw, such as 15-20 Mg/hm², to alleviate compaction in clay loam soils. These findings can provide actionable insights for designing straw-based soil conservation strategies and improving compaction prediction models in mechanized agriculture.

High potato damage and peeling rates have been caused by the potato loading and unloading bag device. It is also unclear on the impact damage. In this study, a potato loading and unloading bag device test bench was constructed to reduce and prevent losses. Two aspects were mainly taken to optimize the structure: the potato collection device and the unloading device. A mechanical structure was adopted with the dual buffering of buffer rollers and limiting rollers, in order to reduce the impact damage of potatoes during bagging; Furthermore, two limiting rollers of "gather caching and separate bagging" mode were used to achieve uninterrupted harvesting for the high bagging efficiency; The lifting slide of the bag unloading device adopted the technology of "gradually decreasing with weight" to control the drop height of potatoes during bagging within a specific range, thus avoiding damage that caused by excessive drop height of potatoes. The position of the buffer roller was adjusted to determine the optimal movement trajectory of the potato, and then minimize the damage during potato bagging. The severity of the impact between potatoes and buffer rollers was evaluated to calculate the maximum contact stress. The main parameters of key components were then determined, according to the main structure and working principle of the device. The impact theory was analyzed during potato bagging. The key influencing factors were clarified on the potato skin damage. RecurDyn and EDEM were coupled to simulate the stress situation of potatoes under roller buffering and non-roller buffering states. The maximum collision contact force of potato blocks with roller buffering was reduced to 263.566 N, compared to those without roller buffering. Taking the conveying speed, buffer roller diameter, and feeding amount as the experimental factors, while the potato damage rate and skin breakage rate as evaluation indicators, a three-factor three-level orthogonal experiment was conducted using Box-Behnken neutral combination design function in Design-Expert. Variance analysis was also performed to analyze the impact of the interaction of various experimental factors on the evaluation indicators using the response surface method (RSM). The working parameters were optimized to determine the optimal values of each parameter, according to actual working conditions. A series of experiments were conducted to verify using an electronic potato impact detector. The results showed that the potato damage rate and skin breaking rate were 0.82% and 1.14%, respectively, when the conveying speed was 0.96 m/s, the diameter of the buffer roller was 83mm, and the feeding amount was 26 t/h. The peak impact acceleration was smaller than the critical damage threshold of potato impact acceleration. At the same time, the impact acceleration at the last point was much smaller than the initial one. The relative errors between the measured and the theoretical values after parameter optimization were 4.06% and 0.4%, respectively. The intensity of the potato impact decreased in a manner like wave, where the impact weakened gradually. Therefore, the potato bagging and unloading device achieved the expected goal of potato collecting and reducing loss. Field experiments showed that the potato damage rates were 0.97%, 1.32%, and 1.58%, respectively, and the skin breaking rates were 1.34%, 1.53%, and 1.87%, respectively, when the harvesting speeds were 0.6, 0.8, and 1.0 m/s, respectively. The high performance was all met the national standards.