# 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
However, at higher speeds, the variation coefficient of the fertilizer discharge uniformity between the two fertilizer discharges is not significantly different, remaining at approximately 5%. Furthermore, the fertilizer discharge quantity of the new fertilizer discharge is notably lower than that of the traditional groove wheel fertilizer discharger, suggesting the need for further enhancements. [PERSON] et al. [26] utilized a straight groove wheel fertilizer discharger to achieve precise fertilizer discharge in blueberry planting. The dimensions and cross-sectional area of the grooved wheel are illustrated in Figure 14. The efficacy of precise fertilization using three nitrogen, phosphorus, and potassium solid granular fertilizers was verified. After measuring the fertilizer discharge quality under various conditions, statistical analysis revealed that the coefficient of variation of fertilizer discharge uniformity from the device exceeded 10%, indicating the need for further research and improvement. While this fertilizer discharger demonstrates relative suitability and accuracy when applying one of the three fertilizers, it falls short of meeting the target fertilization rate when applied to the other two fertilizers. Thus, there is a need to enhance its versatility. The work of Chinese researchers primarily centers on the design and optimization of the structure and working parameters of the fertilizer discharge groove wheel. A method combining discrete element simulation with bench and field trials was used to optimize the  
Figure 14: Structure and dimensions of the straight groove wheel. Figure 13: Pin-roller fertilizer discharger. Note: 1. discharge box; 2. flap; 3. shaft; 4. pin-roller. \(n\) is the number of right and left entry lines, \(\beta\) is the angle between the vertical axis and the right and left entry lines, \(h\) is the height of the roller pin, \(\alpha\) is the angle between the hexagonal polygon and the pin inclination. parameters of the fertilizer discharge groove wheel, resulting in the enhanced stability and uniformity of fertilizer discharge dosing. To investigate the impact of structural parameters of the groove wheel (as shown in Figure 15) on fertilizer discharge performance, [PERSON] et al. [27; 28] utilized polyurea as the test fertilizer to construct a model of the fertilizer filling and discharge process of the fertilizer discharger. Employing the discrete element software EDEM 2018, they analyzed fertilizer discharge performance under various groove wheel parameters, conducting single-factor tests on the fertilizer discharge quantity and multi-factor tests on the fertilizer discharge uniformity. The order of factors affecting fertilizer discharge performance is as follows: sheave radius, arc center distance, and number of grooves. The optimal structural parameters are determined as follows: an arc center distance of 25 mm, a sheave radius of 27 mm, and six grooves. Subsequently, bench tests and whole machine tests were carried out, yielding the fertilizer discharge uniformity coefficients ranging from 91% to 95%. Based on theoretical analysis, [PERSON] [29] examined the fertilizer discharge process of the groove wheel fertilizer discharger through discrete element simulation. Its structure is depicted in Figure 16. Single-factor and orthogonal experiments were devised to process the acquired data. The optimal parameter combination was a rotation speed of the groove wheel of 34.52 rpm, an effective working length of the groove wheel of 56.01 mm, and a depth of the sheave of 36.287 mm. Subsequently, in conjunction with bench testing, it was determined that the variation coefficient of the potassium fertilizer discharge amount was 8.68%, and the variation coefficient of the compound fertilizer discharge amount was 10.64%. The error between the simulated and actual fertilizer discharge amounts was less than 7%. The optimized fertilizer discharger exhibited superior performance in the jujuibe orchard.