# Research Progress Regarding the Precision of Dosing and Distribution Devices for Fertilizers
## 2 Current Status of Research on Precision Fertilizer Dischargers
### Research Status of Groove Wheel Fertilizer Discharge
Figure 16: Schematic diagram of partial structure of groove wheel fertilizer discharger: (**a**) groove wheel; (**b**) shell. Note: \(h\) is the depth of the groove wheel; \(l\) is the effective working length of the groove wheel. Figure 12.0 Schematic diagram of groove wheel structure. Note: \(\mathbf{r}_{1}\) is the arc center distance; R is the radius of the groove wheel. [PERSON] [30] utilized discrete element software EDEM 4.0.0 to investigate the effects of the working length of the groove wheel, the angle of the lower fertilizer discharge tongue opening, and the rotation speed of the fertilizer discharge shaft on the movement trajectory of fertilizer particles. The structure is depicted in Figure 12.1 Through single-factor and multi-factor indoor and field trials, it is concluded that the order and optimal parameter combination of factors affecting fertilizer discharge performance are as follows: 1 Nitrogen fertilizer: a working length of the groove wheel of 40 mm, a fertilizer discharge shaft speed of 46 rpm, an angle of the lower fertilizer discharge tongue opening of 22.5 degrees, and a coefficient of variation of 3.48%. 2 Phosphate fertilizer: a working length of the groove wheel of 42 mm, an angle of the lower fertilizer discharge tongue opening of 22.5 degrees, a rotation speed of the fertilizer discharge shaft of 48 rpm, and a coefficient of variation of 4.274%. 3 Potassium fertilizer: a fertilizer discharge shaft speed of 48 rpm, a working length of the groove wheel of 37 mm, an angle of the lower fertilizer discharge tongue opening of 22.5 degrees, and a coefficient of variation of 5.152%. The results all meet the national precision planting requirements. To further enhance the precision of fertilizer discharge dosing from groove wheel fertilizer discharges, Chinese researchers improved its structure by incorporating a spiral angle into the design, building upon the traditional right-angle fertilizer discharge groove wheel. [PERSON] et al. [31] devised a spiral groove wheel fertilizer discharger, and the structure of the groove wheel is depicted in Figure 12.2 Based on the discrete element method, they simulated the movement of urea fertilizer and investigated the impact of parameters such as groove wheel rotating speed, helix angle, and cross-sectional shape (as shown in Figure 19) on the fertilizer discharge performance. Employing a Box-Behnken three-factor and three-level test, the order of affecting factors is determined as follows: groove wheel speed, wheel cross-sectional shape, and spiral angle. Through thorough data analysis, they identified the optimal cross-sectional shape as scoop shape, and the parameter combination was as follows: a groove wheel rotating speed of 21 rpm and a helix angle of 70 degrees. Simulation tests and bench tests demonstrated that the variation coefficient of fertilizer discharge uniformity does not exceed 9.3%, and the error between simulation and measured data was less than 10%, effectively mitigating the fertilizer discharge blockage and enhancing the discharge accuracy. Figure 12.3 Schematic diagram of partial structure of groove wheel fertilizer discharger: (**a**) groove wheel structure diagram; (**b**) opening diagram of lower row fat tongue. Note: L is the working length of the groove wheel; \(\alpha\) is the angle of the lower fertilizer discharge tongue opening. [PERSON] et al. [32; 33] conducted a systematical investigation into the impact of fertilizer discharge uniformity, considering factors such as the rotation speed of the opposed, double-spiral groove wheel (as shown in Figure 20), groove section radius, working length of the groove wheel, and spiral angle. Discrete element orthogonal experiments were employed to simulate the movement process of various fertilizers, including urea, compound fertilizer, and organic fertilizer. The optimal parameter combination was determined to be a rotation speed of 30 rpm, a groove section radius of 10 mm, a working length of the groove wheel of 50 mm, and a spiral angle of 45 degrees.