Existing devices for dry direct-seeded rice with film mulching in northern China have limitations such as imprecise sowing, unadjustable sowing depth, and seeding device blocking. In this regard, this study proposes a combined seeding method of ‘mini shovel + telescopic pipe’ for dry direct-seeded rice with film mulching. A precision seeder for dry direct-seeded rice with film mulching was developed through theoretical calculations, discrete element modelling (DEM) simulations, and field experiments. The configuration and diameter of the rollers were obtained. Twelve telescopic pipes were evenly distributed on the circumference of the roller, with a contact ratio exceeding one. This ratio reduced the slip rate of the roller effectively. Subsequently, DEM was used to develop a 3³ central composite design. The response surface was established with the sowing depth as the response value. According to agronomic requirements, the sowing depth was set to 20 mm. The optimal combination of working parameters was obtained by optimizing the regression equation. The field experiments showed that the performance of the precision seeder for dry direct-seeded rice with film mulching satisfied the requirements of agricultural production, working stably and reliably. The developed device represents a useful solution for dry direct-seeded rice with film mulching.

Due to factors such as a small amount of fertilizer application during rice topdressing and slow machine speed, the ordinary fertilizer discharge device fails to distribute the fertilizer uniformly and accurately as required, making it difficult to meet the needs of precise rice topdressing. This research focuses on the development of an offset spiral tooth fertilizer discharge device suitable for rice topdressing. The study analyzes the amount of fertilizer discharged in one cycle, the fertilizer force, and the motion of the fertilizer particles. In order to enhance the uniformity of the fertilizer discharge device at a low speed and small volume, the discrete element method is employed to conduct experimental research on the key structural parameters that affect the one-cycle amount of discharged fertilizer and the dynamics of the fertilizer discharge device. Through single-factor tests, it was found that the angle, height, number of spiral teeth, and diameter of the fertilizer discharge wheel are closely associated with the fertilizer discharge performance. To further investigate the impact of these four parameters on the fertilizer discharge performance, a regression combination test of the four factors is conducted based on the range optimized by the single-factor tests. A multi-objective mathematical model, considering the key parameters of fertilizer uniformity coefficient, one-cycle amount of fertilizer, and fertilizer discharge torque, is established at three speeds: 20, 55, and 90 rpm. The response surface method is utilized to analyze the influence of the interaction factors on the fertilizer discharge performance. The optimal combination of the key structural parameters was determined as follows: spiral tooth angle of 35.42°, tooth height of 9.02 mm, discharge wheel diameter of 57.43 mm, and tooth amount of 9.37. The bench test results of the device, using the optimal parameter combination and a fertilizer discharge speed of 0–90 rpm, were obtained for four commonly used rice fertilizers. The maximum variation coefficient of fertilizer discharge was found to be 10.42%. The one-cycle amount of fertilizer discharge was measured to be 19.82 ± 0.72 (A Kang), 17.20 ± 0.69 (Ba Tian), 20.34 ± 0.54 (Yaran), and 14.51 ± 0.44 (granular urea). The fertilizer discharge torque remained stable. These results indicate that the achieved optimization meets the precise fertilizer application requirements and can provide technical support for precise topdressing operations.

The soil in some areas of northern China is heavy owing to the presence of clay and stones, which significantly affects the normal operation of a planter as well as the growth of rice. In this regard, this study proposes a seedbed clearing and shaping device for dry direct-seeded rice, which can be used to remove stones in the seeding area, break soil blocks, for soil leveling, and groove forming. The overall structure and roller of the proposed device was developed based on theoretical calculations, discrete element modeling (DEM) simulations, and field tests. The soil-mixing tooth was distributed on the roller based on the double-helix rule, and the two sides of the helix were configured according to the right-hand and left-hand. Subsequently, DEM was used to develop a 3³ box-bench design. According to the agronomic requirements and operating speed ratio, the forward speed was set to 0.5 m/s. Furthermore, the optimization parameters combination of the device obtained by simulation experiments was: forward speed 0.5 m/s, soil depth 61 mm, and rotation speed 110 r/min, which obtained a stone removal rate of 85.65%, stone removal efficiency of 35.47 pieces/m, operating resistance of 719.23 N, and torque of 174.89 Nm. The field verification test results indicated that the stone removal rate was 77.23% under the optimization parameters combination, and the mean relative error of the simulated experiments value was 8.42%, which showed that the performance of the proposed device functioned stably and reliably, thereby providing a high-quality seedbed for sowing and rice growth. The developed device represents a useful solution for the seedbed clearing and shaping.

The widespread use of chemical herbicides has jeopardized concerns about food safety and ecological consequences. To address these issues and reduce reliance on chemical herbicides, a physical weed control device was developed for the tillering stage in paddy fields. This device features a biomimetic duckbill-like vibration chain that effectively controls weed outbreaks. The chain penetrates the soft surface soil of the paddy field under gravity and rapidly stirs the soil through vibration, leading to the detachment of the weed roots anchored in the surface layer. Simultaneously, the device avoids mechanical damage to rice seedlings rooted in deeper soil. This study aimed to investigate the effects of chain structural parameters (the number of chain rows, vibration amplitude, and length of chains) and operational parameters (vibration frequency and working velocity) on weed control efficiency and rice seedling damage. Through a central composite regression field test, the optimal device structure and operational parameters were determined. The optimization results demonstrated that a vibration amplitude of 78.8 mm, a chain length of 93.47 cm, and 3.4 rows of chains, along with a vibration frequency and working velocity ranging from 0.5 to 1.25 m/s, achieved an optimal weeding effect. Under the optimal parameter combination, field test results demonstrated that approximately 80% of the weeds in the field were effectively cleared. This indicates that the design of the biomimetic duckbill-like vibration chain weeding device exhibits a relatively superior weeding performance, offering a practical solution for the management of weeds in rice fields.