*3.1. Bench Test*

The seed breakage rate ranged from 0.10 to 0.20%, which was negligible. The monitoring results of the sowing amount at different rotational speeds are shown in Table 1 and Figure 8. In order to further evaluate the accuracy of the system's monitoring of the missed seeding amount, the amount of cotton seeds in the seed picking area of the hole seeder was artificially reduced at each rotation speed, so as to increase the missed seeding amount. According to the above method, the actual missed seeding amount on the seed bed belt was obtained. It was compared with the monitoring value of the monitoring system to evaluate the accuracy of the system's missed broadcast detection. Table 2 and Figure 9 show the monitoring results of the leakage amount at different rotational speeds.


**Table 1.** Sowing rate monitoring results of the seed meter at different speeds.

**Figure 8.** The sowing rate monitoring curve of the seed meter at different speeds.


**Table 2.** Missed broadcast monitoring results of the seed meter at different speeds.

**Figure 9.** The missed broadcast monitoring curve of the seed meter at different speeds.

During the whole test process, there was no white crash screen and no wireless data transmission failure. It could be seen from Table 1 that with the increase of the rotation speed of the seed metering plate, the accuracy rate of sowing monitoring did not decrease significantly. The monitoring accuracy rate was above 97%. The reason for the slight decrease in accuracy was that the higher seeding speed would cause some smaller cotton seeds not to be fully filled into the hole, so that they could not be monitored by the sensor. However, the overall sowing rate monitoring accuracy of the system met the needs of cotton precision sowing monitoring. It can be seen from Table 2 that with the increase of the rotation speed of the seed metering plate, the monitoring accuracy of the missed seeding quantity decreased. The reason was that the high rotation speed of the seeding disc caused the seed flow to collide with the seeding tooth disc many times. This produced a small number of broken seeds, which caused the sensor to falsely detect. However, the monitoring accuracy of the system could still reach more than 95%. The monitoring accuracy of missed broadcasts met the requirements of the monitoring system. The above results show that the monitoring system could more accurately judge the seeding amount and the degree of missing seeding for the stable working seed meter. This could be used for evaluation and reference of sowing quality.

#### *3.2. Field Test*

The seed breakage rate ranged from 0.10 to 0.20%, which was negligible. The results of field sowing monitoring are shown in Table 3 and Figure 10. The field test results showed the following: The accuracy rate of broadcast monitoring was maintained above 93%. The accuracy rate of missed broadcast monitoring was maintained above 91%. The seeding monitoring system worked stably and reliably in the field under the rotating speed of the seeding disc that met the seeding requirements. Compared with the traditional monitoring method, the system could detect the seeding device of the hole seeder more accurately, and find the missed seed in time. This effectively saved the amount of cotton seeds, greatly reduced the cost of sowing, and met the requirements for monitoring the sowing status of cotton precision hole seeders.

Compared with the results of the bench test, the monitoring accuracy of the overall system was slightly reduced during the field test. The reason was that the cotton seeds used in the field test had not been selected manually. Some broken seeds and debris were included. The machine vibrated during operation. Moreover, a lot of dust in the field adhered to the color fiber optic sensor probe and affected the optical fiber transmittance. This subsequently calls for enhancement of the monitoring performance of the sensor and optimization of its installation position to ensure more stability. A condenser lens or a selfcleaning dust removal device should also be added to maintain a good light transmittance

of the sensor and improve the environmental adaptability and operational reliability of the system. In the future, high-precision Beidou positioning technology and mobile Internet technology can be combined to provide support for the field sowing map, missed sowing state map, and variable reseeding prescription operations. The parameters of the seeder would also be automatically set, making the system function more in line with the actual production situation and suitable for different operating scenarios.

**Table 3.** Field sowing monitoring test results.


**Figure 10.** The field sowing monitoring curve of the seed meter at different speeds: (**a**) sowing rate monitoring and (**b**) missed broadcast monitoring.

#### **4. Conclusions**

In this study, a planting quality monitoring system suitable for cotton precision planters was designed. The bench performance test of sowing quantity monitoring and missing sowing detection was carried out on the monitoring system. A field test was carried out on the 2MBJ-12 cotton precision film laying planter to verify the reliability of the system. The bench test and field test of the sowing quality monitoring system of the cotton precision planter showed that the sowing quality monitoring system worked stably and reliably. In the bench test, the accuracy of sowing quantity monitoring was no less than 97%, while the accuracy of missing sowing monitoring was no less than 94%. In the field test, the accuracy rate of sowing rate monitoring was no less than 93%, while the accuracy of missed sowing monitoring was no less than 91%. This improved the work quality and work efficiency of cotton sowing. It met the requirements for monitoring the sowing quality of cotton precision hole seeders.

**Author Contributions:** Conceptualization, Y.Y. and B.Z.; methodology, S.B. and K.N.; software, S.B. and Z.S.; validation, S.B. and Y.Z.; formal analysis, K.N. and S.B.; investigation, S.A. and Y.M.; resources, Y.Y. and B.Z.; data curation, S.B. and L.W.; writing—original draft preparation, S.B.; writing—review and editing, K.N. and L.L.; visualization, Y.Z. and L.Z.; supervision, Y.Y. and B.Z.; project administration, Y.Y. and K.N.; funding acquisition, K.N. and L.Z. All authors have read and agreed to the published version of the manuscript.

**Funding:** This work was mainly supported by the Autonomous Region Regional Collaborative Innovation Special (Science and Technology Aid to Xinjiang Program) Project of China (2021E02055).

**Data Availability Statement:** Data are contained within the article. The data presented in this study can be requested from the authors.

**Conflicts of Interest:** The authors declare no conflict of interest.

### **References**

