In view of the existing composite planting, which cannot independently control the fertilizer rate for each row, fertilizer is prone to moisture solidification caking and relies on a single way to measure the speed of inaccurate problems, a split-drive variable fertilizer application system was designed for soybean and maize strip cropping composites. It includes roller crushing bi-directional spiral fertilizer discharger, split-drive variable fertilizer application system and ‘GNSS + encoder’ dual speed measurement system. By modeling agglomerated fertilizer particles, a discrete element simulation was carried out to analyze the crushing effect. The speed measurement error variation folds of both GNSS and encoder under different speed conditions were obtained through field speed measurement tests. Finally, 4.5 km/h was identified as the switching point between the two speed measurements. Through bench testing, a mathematical relationship model was developed for the soybean and maize belts in terms of ‘Fertilizer Application Rate - Operating Travel Speed - Metering Mechanism Rotor Speed’, and the results are presented in the table below. Fertilizer discharge consistency was verified for fertilizer dischargers. Field trials were conducted, and the results show: The soybean belt had a maximum error of 4.81% at a fertilizer application rate of 150 kg/hm² and an operating speed of 5 km/h; the maximum error in the corn belt was 4.67% at a fertilizer application rate of 600 kg/hm² and operating speed of 4 km/h. Both have a maximum error of less than 5%, which meets the requirements for variable fertilizer application.

Chopped and spread maize stalks improve soil structure and fertility. However, because of the absence of research on airflow distribution in the chopping chamber, improvement of the spreading uniformity of chopped stalks has been limited. Therefore, in this study, computational fluid dynamics (CFD) technology was applied to analyze the influence of structural and operational parameters of the chopping and spreading machine on the velocity, pressure, and turbulent kinetic energy distribution of airflow in the chopping chamber. The experimental factors considered were the relative position angle (RPA) between the collecting-chopping shaft and the sliding-supporting shaft, working velocity (WV) of the chopping chamber, and rotational velocity of the collecting-chopping blade (RVCCB). The results revealed that RPA and RVCCB had a significant influence on the maximum negative pressure in the inlet (MNPI), the proportion of negative pressure area at inlet (PNPAI), and the maximum pressure drop at inlet and outlet (MPDIO). Additionally, RVCCB had a strong influence on the maximum velocity, average velocity, and velocity variation coefficient of airflow at the outlet. Moreover, maximum turbulence (MT) and maximum turbulent kinetic energy dissipation rate (MTKEDR) showed a positive relationship with RVCCB. To determine the values of RPA, RVCCB, and WV, a multivariate parameters optimization regression model was constructed, which yielded the optimal values of 15°, 1800 r/min, and 0.50 m/s, respectively. Subsequently, a hyperbolic spiral-type guiding shell with an arc length of 90° was designed to enhance the uniform distribution of airflow in the chopping chamber. Finally, a validation experiment of airflow distribution was conducted. The results showed that the velocity difference between the simulation and the validation experiment was less than 15%, indicating the accuracy of CFD simulation, and the spreading uniformities of the chopped stalks were better than national standards. These findings can serve as technical and theoretical support for the design and optimization of chopping and spreading machines.