# Research Progress Regarding the Precision of Dosing and Distribution Devices for Fertilizers
## 2 Current Status of Research on Precision Fertilizer Dischargers
### Research Status of Spiral Fertilizer Dischargers
Field trial results indicate a relative error of 2.33% between the actual and target fertilizer application amounts, meeting the requisites for basal fertilizer application quantity and fertilizer uniformity. [PERSON] et al. [18] devised the bidirectional spiral blade for the fertilizer discharge apparatus of the double-side deep fertilization device used in potato cultivation. Through a combination of kinematic analysis and single-factor discrete element simulation testing of polyaspartate boric acid compound fertilizer within the fertilizer discharge  
Figure 6: Fertilizer discharge shafts with different pitches in the feeding section. Figure 1:0 Fertilizing spirals with different numbers of heads. apparatus, optimal parameters for the two-side spiral device were determined to be a single-spiral blade length of 120 mm, a spiral outer diameter of 56 mm, and a pitch of 45 mm. Its structural configuration is depicted in Figure 1:1 Subsequently, the apparatus underwent testing under static working conditions, resulting in a concluded coefficient of variation for fertilizer discharge uniformity of 2.29%. This fertilizer discharge exhibits commendable stability in the fertilizer discharge. To further enhance the precision of fertilizer discharge dosing from the spiral fertilizer discharger, Chinese researchers studied the structural parameters of the fertilizer discharge port. [PERSON] et al. [19,20] investigated the structure of the fertilizer discharge port, analyzing its impact on the performance of the boron sulfate compound fertilizer discharge. Through discrete element orthogonal simulation tests and bench trials, the optimal parameters are determined as follows: an outlet angle of 135 degrees and a length of 40 mm (1.5 times the pitch), as illustrated in Figure 1:2 Combined with the field trial verifications, it was observed that the optimized fertilizer discharge stability and uniformity of fertilizer discharge were significantly enhanced, with the variation coefficient of fertilizer discharge not exceeding 8.22%. Moreover, the error in the fertilization amount was less than 4%, meeting the precise fertilizer discharge requirements for corn fields per acre. In addition, in order to make breakthroughs in the precise fertilizer discharge dosing from the spiral fertilizer discharger, Chinese researchers are also dedicated to exploring new designs for spiral fertilizer discharges. To address the issue of flow fluctuation in the fertilizer discharge from single spiral fertilizer dischargers, [PERSON] et al. [21] devised a spiral double-wheel fertilizer discharg, as depicted in Figure 1:3 The impact of structural parameters on the performance of the Stanley compound fertilizer discharge was theoretically analyzed. Through the establishment of  
Figure 1:4 Two-sided spiral device. Note: \(S_{c1}\) is the length of the spiral blade, \(D_{c1}\) is the spiral outer diameter, \(S_{d}\) is the pitch. Figure 1:5 Structural diagram of the fertilizer discharge port: (**a**) schematic diagram of the angle of the fertilizer outlet; (**b**) schematic diagram of the length of the fertilizer outlet. Note: \(\alpha\) represents the angle of the fertilizer discharge port; L represents the length of the fertilizer discharge port. a discrete element mathematical model, a genetic algorithm was employed to optimize the fertilizer discharger's structure. Following optimization, the structural parameters are determined to be a center distance of 49.8 mm, a pitch of 32.5 mm, a blade height of 15.2 mm, a blade thickness of 2.3 mm, and a spiral blade inner diameter of 13.6 mm. The fertilizer discharger is capable of achieving an even fertilizer discharge while increasing the discharge amount. Combined with the bench test verification, the variation coefficient of the fertilizer uniformity can reach a minimum level of 6.78%, enabling precise fertilization control through speed adjustments.