To analyze the process of wet clay soil adhering to the rotary tillage part during rotary tillage in paddy field, simulation tests were carried out based on the discrete element method (DEM) in this study. The Plackett-Burman (PB) test was applied to obtain simulation parameters that significantly affected the soil adhesion mass. The Box-Behnken design (BBD) based on the principle of response surface method (RSM) was used to establish a regression model between significant parameters and soil adhesion mass. The soil adhesion mass obtained from the actual soil bin test as the response value was brought into the regression model. The optimal simulation parameters were obtained: the particle-particle coefficient of rolling friction, the particle-geometry coefficient of static friction, and the particle-particle JKR (Johnson-Kendall-Roberts) surface energy were 0.09, 0.81, and 61.55 J·m⁻², respectively. The reliability of the parameters was verified by comparing the soil adhesion mass obtained under the optimal simulation parameters with the actual test value, and the relative error was 1.84%. Analysis of the rotary tillage showed that soil adhesion was mainly concentrated in the sidelong section of the rotary blade. The maximum number of upper soil particles adhering to the rotary tillage part was 2605 compared to the middle soil and lower soil layers. The longer the distance the rotary tillage part was operated in the soil for, the more soil particles would adhere to it. This study can provide a reference for the rational selection of simulation parameters for rotary tillage and the analysis of soil adhesion process in rotary tillage.

For paddy-upland rotation areas in the middle and lower reaches of the Yangtze River, the paddy soil has undesired physico-mechanical properties of tillage during the dry season. The purpose of this study is to determine the effects of soil bulk density and moisture content on the physico-mechanical properties of paddy soil in the plough layer. The bulk density and moisture content were selected as experimental factors, and the cohesion, tangential adhesion, plasticity index, and soil swelling rate were chosen as experimental indices from physico-mechanical properties of paddy soil in the plough layer. The experimental factors were quantitatively analyzed to explore the change characteristics of the physico-mechanical properties of paddy soil in the plough layer. Conclusions were obtained that show that when the bulk density increased in the range of 1 to 1.6 g·cm⁻³, the cohesion, tangential adhesion, plasticity index, and swelling rate of paddy soil increased in different degrees. Between 15% and 35% moisture content, the cohesion increased first and then decreased with the increase of moisture content, while the peak cohesion value occurred at the moisture content of 20%. Moisture content was positively correlated with tangential adhesion and negatively correlated with soil swelling rate. This study provides a reference for the regulation of paddy soil tillability in the middle and lower reaches of the Yangtze River Basin.

In order to solve the problems of poor seed filling performance and the low compensation accuracy of large- and medium-sized missed seeding compensation devices under medium- to high-speed conditions, a pneumatic missed seeding automatic compensation system based on speed synchronization was designed. The key structure and parameters in terms of the seed metering plate and seed feeding arm were determined by theoretical analysis. A universal compensation control system for single-seed missed seeding and continuous missed seeding was designed. With regards to exploring the working performance, some relevant bench tests were carried out, with Zhengdan-958 corn seeds and Zhonghuang-37 soybean seeds serving as the test objects. First of all, a single-factor test was conducted to determine the optimal level ranges of the factors that influence seed filling performance, such as suction hole diameter, seed stirring bar thickness, and negative pressure. The test indicators were qualified seed filling rate, multiple seed filling rate, and missed seed filling rate. Next, the Box–Behnken design test was executed to explore to the influence law of each test indicator on corn seed filling performance. Then, the parameter optimization module was applied to achieve the best combination of operating parameters for the test factors. The optimal combination of parameters was a suction hole diameter of 5.3 mm, seed stirring bar thickness of 2.9 mm, and negative pressure of 4.1 kPa. Based on the optimal combination, a verification test of corn seed filling performance was performed, and the corresponding evaluation indexes were a qualified seed filling rate of 95.46%, multiple seed filling rate of 2.47%, and missed seed filling rate of 2.07%. Lastly, a seed feeding performance verification test was employed with the seeding speed as the impact factor to verify the compensation accuracy of single-seed missed seeding and continuous missed seeding compensation. The results of the verification test indicate that, for corn seeds, when the seeding speed falls within the range of 8 to 12 km/h, the effective single-seed feeding rate exceeds 88%, the average single-seed feeding time is less than 0.18 s, the qualified seed feeding rate is higher than 90%, the multiple seed feeding rate is lower than 3%, and the missed seed feeding rate is below 7%. For soybean seeds, the effective single-seed feeding rate is higher than 85%, the average single-seed feeding time is less than 0.17 s, the qualified seed feeding rate exceeds 86%, the multiple seed feeding rate is less than 4%, and the missed seed feeding rate is below 10%. This system meets the agronomic requirements for the automatic compensation of missed seeding with respect to large- and medium-sized precision seeders, which could help to improve the operational performance of seeding machines.

Design and experimental of anti-adhesion rototiller based on staggered double-roller scraping