# Research Progress Regarding the Precision of Dosing and Distribution Devices for Fertilizers
## 2 Current Status of Research on Precision Fertilizer Dischargers
### Research Status of Disc Fertilizer Discharge
[38] used a spiral blade working mechanism to replace the straight blade, depicted in Figure 25. Experimental tests indicate that this innovation can enhance fertilizer distribution quality within the speed range of 4 to 16 kph. By adjusting the blade angle ranging from 0 to 20 degrees to optimize fertilizer dispersion, the developed fertilizer discharger can distribute fertilizers at higher speeds and more evenly across the field surface, with relevant parameters showing significant improvements over traditional devices. The work of Chinese researchers primarily centers on the design and optimization of the structure and working parameters of fertilizer spreading discs. They employ a method  
Figure 23: Two discs with different blade angles: (**a**) the I3 vane configuration; (**b**) the I0 vane configuration. Figure 24: Inclined axis centrifugal rotary disk fertilizer applicator. Figure 25: Structural diagram of disc fertilizer discharger. that combines discrete element simulation with bench and prototype testing to continually optimize the parameters of the fertilizer spreading disk, aiming to improve the stability and uniformity of fertilizer distribution. [PERSON] et al. [39] focused on the centrifugal disc fertilizer discharger as their research subject, depicted in Figure 26. They conducted a prototype test to analyze the impact of key parameters on the uniformity of urea fertilizer spreading. Through a multi-factor response surface analysis test, they concluded that the order of factors affecting fertilizer spreading uniformity was as follows: feeding position angle, fertilizer spreading height, and blade position angle. By employing factor interaction response surface analysis, they determined the optimal parameter combination to be a fertilizer spreading height of 68.8 cm, a cutting position angle of 60 degrees, and a blade position angle of 29.63 degrees. With these settings, the coefficient of variation of fertilizer uniformity reached a minimum value of 9.95%, effectively resolving the issue of poor fertilizer discharge uniformity. To achieve advancements in the precise distribution of fertilizers by disc fertilizer dischargers, Chinese researchers are dedicated to developing new designs for disc fertilizer dischargers. They utilize fertilizer discharge ejector pins and fertilizer scraping brushes to aid in the fertilizer discharge. [PERSON] et al. [40,41] developed a disc ejection side-deep fertilizing device. The cross-section of the fertilizer trough is illustrated in Figure 27. A kinematic model of the fertilizer discharge process was established and determined through discrete element simulation tests. The optimal working speed of the fertilizer discharge disc ranges from 10 to 60 rpm. Choosing the effective working length of the fertilizer trough as the test factor, results indicate that adjusting the effective working length of the fertilizer trough between 5 to 20 mm leads to a variation coefficient of fertilizer discharge uniformity ranging from 5.96% to 12.77%. Four special compound fertilizers with varying densities for side-deep fertilization of paddy fields were selected for testing. The device demonstrates good adaptability and meets national operating standards. To further enhance the precision of fertilizer distribution from disc fertilizer dischargers, Chinese researchers additionally devised a fertilizer spreading disc featuring a conical blade shape and examined its structure and working parameters. [PERSON] et al. [42] devised a conical disc push plate double-row fertilizer discharg. The structure of the conical disc is depicted in Figure 22.0 The impact of the number of push plates on fertilizer filling and discharge performance was analyzed through discrete element simulation. Findings reveal that with eight push plates, the fertilizer discharger exhibits optimal performance.