It is inevitable that reclaimed cotton stalks will contain a certain amount of plastic film due to the wide application of plastic mulching during the process of cotton cultivation, and this makes it inappropriate to return it to the field or for it to be processed into silage. In this study, biochars were prepared by the co-pyrolysis of cotton stalk with low-density polyethylene (LDPE) in the proportions of 1:0, 3:1, 2:1, and 1:1 (w/w) at 400 °C, 450 °C, and 500 °C and maintaining them for 1 h. The effects of the co-pyrolysis of cotton stalk with LDPE on the properties of biochars (e.g., pH, yield, elemental analysis, specific surface area, etc.) and the Pb(II) removal capacity were analyzed. Co-pyrolysis cotton stalks with LDPE could delay the decomposition of LDPE but could promote the decomposition of cotton stalk. At 400 °C and 450 °C, the addition of LDPE decreased the H/C ratio, while no significant difference was found between the pristine biochar and the blended biochar pyrolyzed at 500 °C. An FTIR analysis indicated that the surface functional groups of biochar were not affected by the addition of LDPE, except for CH₃ and CH₂. The results of the SEM showed that LDPE could cover the surface of biochar when pyrolyzed at 400 °C, while many macropores were found in the blended biochar that was pyrolyzed at 450 °C and 500 °C, thus increasing its surface area. The blended biochar that was pyrolyzed at 500 °C was more effective in the removal of Pb(II) than the cotton-stalk-derived biochar, which was dominated by monolayer adsorption with a maximum adsorption capacity of approximately 200 mg·g⁻¹. These results suggested that the co-pyrolysis of cotton stalks and LDPE may be used to produce biochar, which is a cost-effective adsorbent for heavy metal removal from aqueous solutions.

With the extensive use of plastic film mulching in planting, the amount of residual plastic film in soil has been increasing, causing soil and water pollution, harming crop growth, and reducing agricultural product quality and yield. In response to this issue, this study proposes a roll-type residual film recovery mechanism using the tillage layer method. The structure and operation principles of this system are discussed, and a detailed analysis of its key components and working process is provided. The lifting cutter operates at a speed of 22.37 rad/s, the pick-up drum at 4.58 rad/s, the roll forward rotation picks up the film at 13.74 rad/s, and the roll reverse film rotation unloads the film at 17.57 rad/s, with the unloading wheel rotating at a speed of 4.5 rad/s. ADAMS (software of automatic dynamic analysis of mechanical systems) Version No.2019 is used for modeling and analysis, and the displacement and velocity change patterns of MARKER_499, MARKER_500, and MARKER_505, which are marked points of the spring-tooth tips and are found to be the same. The maximum resultant displacement of MARKER_499 and MARKER_500 is 22.146 mm when picking up plastic film and 17.047 mm when unloading plastic film. Meanwhile, the maximum resultant displacement of MARKER_500 and MARKER_505 is 231.715 mm in the film-picking area and 234.028 mm in the film-unloading area. After analyzing the velocity of MARKER_499 during picking and unloading of the film, it was determined that the absolute velocity for the picking direction was 79,809.407 mm/s, and for the unloading direction it was 10,2266.168 mm/s. Bench tests show a tillage gathering rate of 71.6% and a surface gathering rate of 83.4%, meeting the performance requirements of the roller-type residual film recovery mechanism. These findings provide a theoretical basis for the design of the structure and operational parameters for the roll-type residual film recovery mechanism using the tillage layer method.

In view of the low degree of mechanization and poor quality of harvesting of edible sunflower after drying, an in situ bionic harvesting device was designed, which can achieve low-loss harvesting of edible sunflower without removing the edible sunflower disc. According to the physical characteristics of sunflower stalks in the field, influencing factors of in situ low-loss feeding were obtained, and the structural parameters of the in situ feeding mechanism were determined. Based on bionic technology and static analysis, the influencing factors on the performance of the bionic threshing mechanism were obtained. By analyzing the mechanical characteristics of edible sunflower seed, the operation parameters of the seed collection mechanism were determined. Based on the structural analysis results of the harvesting device, a response surface optimization test was carried out. The test results show that when the average rotation speed of the bionic loosening roller was 113.57 rpm, the average rotation speed of the simulated artificial striking roller was 230.80 rpm, the average forward speed of the harvesting device was 0.58 m/s, the working quality of the harvesting device was the best, the seed loss rate was 2.12%, and the edible sunflower disc threshing rate was 98.96%. A field verification test further confirms that under the optimal working parameters, the relative deviation between test indexes and response surface optimization test results was less than 2%. During the operation process, the movement of key components of the harvesting device was coordinated and stable. The research results can provide new ideas for the mechanized harvesting of the edible sunflower disc after drying.

The working principle and key components of a chain drive residual film recovery machine were studied. A kinematic analysis of the chain drive soil separation mechanism was completed by applying ADAMS software to obtain the trajectory, displacement, velocity and acceleration of the center of mass of the chain plate link_1 in the x- and y-directions within the effective shaking displacement. A field test of the chain drive separation mechanism was carried out. When the shaking roller was in contact with the chain, the change in speed of the chain in the x- and y-directions was not significant, but the force in the y-direction was conducive to breaking the soil pieces and improving the rate of collecting the residual film. The change in the speed of link_1 in the y-direction speed with x-direction speed explained the action of the separation mechanism on conveying and throwing of the film-soil mixture in the horizontal and vertical directions, which revealed the mechanism of the chain drive film-soil separation equipment. The field test showed that the film collection rate of the chain drive separation mechanism was 68%, and the surface residue was 6%. The test results meet the relevant national and industry standards and design requirements. The results of this study provide guidance for the design and optimization of chain drive film-soil separation equipment.

Highlights This study designed an air-suction jujube picking and conveying device to address the problems of low transport efficiency and high damage rate. Theoretical analysis, Fluent software simulation, and prototype testing determined the diameter of the conveying pipe, the inlet and outlet diameters of the suction chamber, and the fan type and speed. A Box-Behnken center combination design in Design-Expert software was used to perform response surface orthogonal tests to optimize the device. This study provides a reference for further optimization of the air-suction jujube picking and conveying device. Abstract. To address the problems of low transport efficiency and high damage rate, an air-suction jujube picking and conveying device was designed. The main components of the device include the fan, suction chamber, and conveying pipe. Simulation of the conveying pipe and suction chamber was performed using Fluent software, and the airflow rate and pressure were analyzed for conveying pipes of five different diameters and suction chambers with different inlet and outlet diameters. In the simulation results, the diameter of the conveying pipe was 105 to 165 mm, and the outlet diameter of the suction chamber was 150 to 210 mm. The Box-Behnken center combination design method in Design-Expert software was used to perform response surface orthogonal tests with the conveying pipe diameter, suction chamber outlet diameter, and fan speed as the test factors, and the jujube conveying rate and breakage rate as the target values. The results show that the order of the test factors on the jujube conveying rate is: fan speed = conveying pipe diameter > suction chamber outlet diameter, and the order of the test factors on the jujube breakage rate is: fan speed > suction chamber outlet diameter > conveying pipe diameter. The experimental results were verified in field tests with the optimized parameters. When the conveying pipe diameter was 165 mm, the suction chamber outlet diameter was 200 mm, and the fan speed was 3254 rpm, the average jujube conveying rate in the verification test was 238.68 kg h-1. The relative error between the experimental verification value and the theoretical optimized value was 1.44%, which is less than 5%. The average value of the jujube breakage rate in the verification test was 2.18%. The relative error between the experimental verification value and the theoretical optimized value was 3.81%, which is also less than 5%. This study provides a reference for subsequent research and optimization of the air-suction jujube picking and conveying device. Keywords: Air suction, Conveying device, Conveying pipe, Jujube, Suction chamber.

To solve the problems of high temperature and drought in the Xinjiang Turpan area and the low survival rate of melon seedlings transplanted into dry soil, existing transplanters for large plant type young melon seedlings can be mechanized. For non-destructive planting for small plant types, such as Hami melon seedlings, there are still poor transplanting effects, planting point precise pile-soil, and other problems. In this study, a water transplanter for laying pipe and film for Hami melons was designed to mechanize the operation of rotating tillage, laying film and covering soil, transplanting potted seedlings on film, and water injection of the seedling root and planting hole, and soil piling and suppression. In this study, a transplanter was designed by coupling the motion of an earth-covering roller and a duck’s mouth planter and realized the precise mound of soil in the planting hole, solved the difficult problem of the precise mound of soil on the membrane, and at the same time carried out water injection on the root of the melon seedlings, which effectively solved the problem of low survival rate of transplanted seedlings in the arid region of Turpan, Xinjiang, China. Field experiments showed that the survival rate of melon seedlings under drip irrigation for 8 h after transplanting into dry soil exceeded 97%. The efficiency of mechanized operation can reach 1 mu/person/hour, which is more than 8 times higher than manual operation. The operation speed of the machine is 1~1.2 m/s, and the qualified transplanting rate is 93.26%, which meets the requirements of cantaloupe transplanting agronomy. This study provides a new method for dry soil cantaloupe transplanting. This article can also provide a design reference for Hami melon transplanting mechanization in arid areas.