As the complex terrain in hilly areas is not conducive to corn mid-tillage precision fertilization, a corn-overlapped strip fertilizer spreader was designed without an external power source. By configuring a passive overlapping spreading method with a three-branch split chamber structure, the uniform spreading of fertilizer in strips was achieved. A horizontal and vertical movement model of fertilizer spreading was developed to determine the angle of the fertilizer extending tube, the width of fattening small plates, and the height of the fertilizer spread as the main factors affecting the fertilizer distribution pattern. The single-factor ternary orthogonal rotational combination response surface simulation test was carried out with pendulum angle, width, and height as test factors and the transversal fertilizer uniformity coefficient and longitudinal fertilizer uniformity coefficient as test indicators. The test results showed that the pendulum angle, height, and width had significant effects (p < 0.05) on the transversal fertilizer uniformity coefficient, and the pendulum angle and width had a considerable impact (p < 0.05) on the longitudinal fertilizer uniformity coefficient. In the optimal combination of parameters, swing angle 52°, height 400 mm, and width 50 mm operation, the coefficients of uniformity of both the transversal fertilizer uniformity coefficient and longitudinal fertilizer uniformity coefficient were less than 0.15%. A verification test was carried out under the optimal combination of parameters for the simulation tests with the simulation conditions as the standard. The test results were consistent with the simulation results within the error range. The deviation values of the transversal fertilizer uniformity coefficient and longitudinal fertilizer uniformity coefficient were 8.11% and 9.01%, respectively. The corn-overlapped strip fertilizer spreader was able to complete the fertilizer spreading operation smoothly. This study provides evidence for further optimizing the performance of the corn mid-tillage fertilizer applicator.

Due to the unique structural characteristics of the traditional spiral fertilizer applicator, the instantaneous filling coefficient cannot be determined, which is not conducive to achieving precise control of the fertilizer discharge rate. Therefore, a spiral-pushing fertilizer applicator has been designed. By using a structure of variable diameter and variable spiral pitch to squeeze fertilizer gradually, precise control of the fertilizer discharge is achieved. The study analyzes the effects of screw pitch, screw diameter, and rotational speed on the filling coefficient; it uses spiral pitch elongation percentage, spiral diameter elongation percentage, and rotational speed as experimental factors, and filling coefficient and particle axial velocity coefficient as experimental indicators. Through quadratic orthogonal rotation combination design experiments, the fertilizer discharge performance of the spiral-pushing fertilizer applicator was optimized. The experimental results indicate that for the filling coefficient, x₁x₂ has an extremely significant impact, while for the axial velocity coefficient of particles, x₁ and x₃ have an extremely significant impact. When the rotational speed x₃ is 30 r/min, the optimized spiral pitch elongation percentage x₁ is 189.82–200%, the spiral diameter elongation percentage x₂ is 102.75–106.76, the filling coefficient is greater than 95%, and the particle axial velocity coefficient is less than 10%, achieving the best fertilizer discharge performance. An electrically controlled fertilizer discharge system was also designed, and bench tests were conducted on it. The results show that the average deviation between the fertilizer discharge performance of the spiral-pushing fertilizer applicator driven by the electrically controlled fertilizer discharge system and the preset value is 2.14%. This proves that, when the fertilizer demand changes, the fertilizer discharge flow can be adjusted through the electrically controlled fertilizer discharge system to achieve precise fertilization. This study provides a reference for the design of spiral fertilizer applicators.

Precision fertilizer application technology is necessary to improve fertilizer utilization efficiency in agricultural production. To achieve precision fertilizer application and solve problems in production practice that contain the structure problem of the traditional mechanical fertilization systems, and the fertilizer discharger is blocked and can not achieve uniform fertilization because the fertilizer contains caking fertilizer in response to the characteristics of conventional fertilizers containing caking fertilizers, innovative design and system experimental simulation studies were carried out. A gap squeeze gear-type fertilizer dis-charger was designed, and fertilizer caking crushing was achieved by configuring the gear gap squeezing method. Combined with engineering practice, two mixed fertilizers (granular fertilizer with caking fertilizer) were constructed and blended by using BPM (Hertz Mindlin with bonding) discrete element, the fertilizer discharger was used as the object of study to simulate and experimentally investigate the process of crushing and discharging of mixed fertilizer and the process of uniform discharging of mixed fertilizer. The simulation test model of the separation device with vibration screen of the caking fertilizer and granular fertilizer after fertilizing was established to study the crushing rate of the caking fertilizer, and the simulation model with collection plate of the uniformity of the mixed fertilizer discharge was based on to explore the uniformity of the mixed fertilizer. The L₉ (₃⁴) orthogonal test was carried out under the conditions with the number of teeth, pressure angle, and fertilization gap as test factors and the fertilizer crushing rate and fertilizer uniformity coefficient as test indicators. The test results showed that the number of teeth and pressure angle had significant effects (0.01 < P < 0.05) on the crushing fertilizer rate and fertilizer uniformity, and the fertilization gap had no significant impact (P༞0.05) on the crushing fertilizer rate and fertilizer uniformity. In the optimal combination of parameters, the number of teeth 6, pres-sure angle 15 °, fertilization gap 6mm operation, the coefficient of uniformity of crushing fertilizer rate and fertilizer uniformity were 74.89% and 17.21%, respectively. The bench test results compared with the outer groove wheeled fertilizer drainer showed that the optimized gap squeeze gear type fertilizer discharger has higher fertilizer crushing quality at different speeds, and the fertilizer crushing rate and uniformity were79.69% and 18.56%, respectively, within the error range. The simulation results are in general agreement. This study provides evidence for fertilizer discharger structure design and enhances the effect of fertilizer discharger crushing.

Precision seeding of micro-sized millet seeds in plot breeding faces critical challenges, including high miss-seeding rates and severe seed cross-contamination during variety changeovers. This study developed a novel bilateral staggered wheel-spoon precision seed-metering device to achieve precise hill-dropping of 5–8 seeds per hole, zero-residue rapid clearing, and high-precision low-speed seeding without seed damage. The device features a horizontal-axis bilateral staggered arrangement of 20 seed spoons, a lateral gravity seed-dropping mechanism and a semi-enclosed seed chamber. Discrete Element Method (DEM) simulation and Central Composite Design (CCD) response surface methodology were applied to optimize seed spoon cavity dimensions, followed by machine vision bench tests and field validation. Kinematic analysis verified that 20 staggered spoons effectively prevent centrifugal seed scattering. The optimized cavity has an effective depth of 4.4 mm, width of 4.1 mm and height of 2.7 mm, with a simulated seeding qualification rate above 92%. Bench tests at 9 rpm delivered a 92.67% qualification rate, 3.33% re-seeding rate and 4.00% miss-seeding rate. Field trials across three millet varieties maintained qualification rates ≥88%, with an 8.5-second zero-residue clearing process. This device resolves the conflict between micro-seed precision hill-dropping and efficient contamination-free clearing, fully satisfying the agronomic demands of millet plot precision breeding.