Droplet characteristics are identified as essential factors in agricultural spray application. The aims of this study were to analyse the influence of spray parameters on droplet characteristics and to determine possible candidate sprays that would produce the same droplet size categorizations as the American Society of Agricultural and Biological Engineers (ASABE) standard S-572.1 for air induction nozzles (AINs). Six different orifice sizes of the Billericay Farm Services (BFS) air induction (AI) flat fan hydraulic nozzles (the air bubblejet) were examined at different spray pressures (200 kPa, 300 kPa, 400 kPa, 500 kPa, 600 kPa and 700 kPa) and concurrent air velocities (2 m/s, 3 m/s, 4 m/s and 5 m/s). The influences of spray parameters on the droplet characteristics were analysed using analysis of covariance (ANCOVA) and analysis of variance (ANOVA). Results showed that: (1) The values of droplet characteristics and the results of ANOVA were significantly different before and after eliminate the influence of dynamic surface tension (DST) on droplet characteristics by ANCOVA; (2) (a) the reduction rates of the droplet diameter sizes decreased with increasing spray pressure; (b) air velocities of 2 m/s and 5 m/s resulted in smaller droplets reports, and air velocities of 3 m/s and 4 m/s are more suitable for agricultural spray applications; (c) a larger nozzle orifice size not always result in a larger droplet size and (3) Fine, Medium, Coarse, Very Coarse and Extremely Coarse droplet classification categories as the ASABE S-572.1 standard categorizations were determined to classify AINs.

Review of precision rice hill-drop drilling technology and machine for paddy

The feasibility of aerial fertilization by UAV-based granular fertilizer spreaders (GFSs) has been widely accepted. Although commercial UAV-based spreaders have emerged, their performance in granular fertilizer spreading application has rarely been studied. This paper tested the performances of four existing UAV-based GFSs in the automatic controllability, range of the discharge rate and the swath width and uniformity of the distribution. An analytic hierarchy process (AHP)-based method was proposed to evaluate their comprehensive performance in spreading application. The main results are as follows: (a) GFS-A showed the maximum controllable discharge rate of 27 kg/min, and GFS-B showed the minimum (proximately 3 kg/min). The discharge rate could be changed in a stepless way by GFS-B, C and D. The relationship between the discharge rate and the rotational speed of the fluted roller of GFS-D showed a significant linear relationship ( $\text {R}^{2} = 0.9991$ ) for the operational range. (b) The distribution patterns of GFS-A and D were trapezoidal, which was the better deposition pattern for generating uniform spreading; those of the other two UAV-based GFSs were a wide triangle with obviously asymmetrical sides (GFS-B) and a typical M-shape with two peaks (GFS-C). (c) the simulation of CV-swath width illustrated that the available effective swath width (CV ≤ 20%) for these UAV-GFSs were 5.1m (CV = 14.73%), 4.8m(CV = 17.55%), 3.9m(CV = 13.02%) and 5.7m(CV = 18.36%) respectively under the given conditions. Furthermore, according to the AHP-based evaluation model, it was proved that GFS-D was able to provide superior performance in precise fertilization for a large application range, which is important for its practical application. This comparative study makes useful contribution for farmers and researchers in this field in understanding the application performance of various UAV-based GFSs.

Optimization of variables for maximizing efficacy and efficiency in aerial spray application to cotton using unmanned aerial systems

Vegetables are an essential part of people’s daily diet, and weeds can cause serious losses in vegetable yield and quality. Intelligent weeding technology for vegetables will be one of the mainstream technologies in modern agricultural development. This article reviews the current research status of intelligent weeding technology for vegetables, including vegetable and weed detection technology, weeding actuators, and weeding robots. Firstly, the vegetable and weed detection technology was introduced in detail from three aspects: global weed detection, crop-rows detection, and vegetable/weed precise recognition technology. The research results of some researchers were summarised, and the vegetable/weed precise recognition technology, including machine learning and proximal sensor technology, was introduced. Secondly, the weeding actuators and robots were introduced, including intelligent chemical weeding, mechanical weeding, physical weeding, and integrated weed management methods. Some weeding actuators and robots developed by researchers and agricultural companies were showcased. Finally, the challenges and future development directions of intelligent weeding technology were discussed and analysed. Intelligent weeding technology for vegetables is still mainly limited by natural conditions and a lack of technology. In the future, it will be possible to develop in the direction of multi-algorithm and multi-sensor fusion technologies. It is necessary to improve the applicability of intelligent weeding equipment for various environments, crops, and weeds. This article can provide a reference for future research in the field of intelligent weeding for vegetables.

Highlights The problems of high resistance to seed sucking and the poor stability of seed sucking were solved. A mechanical model was established for seeds in a seed stirring device. The optimum parameters of the seed stirring device were obtained. Seeding precision was improved, providing a reference for the seed sucking process. Abstract. To achieve a goal of precision seeding with 1 to 3 seeds per hill and to solve problems in a pneumatic rice seed metering device, including high resistance to seed sucking, poor stability of seed suction, and low seeding precision, a cylindrical seed stirring device was designed. The design was based on the characteristics of the rice seed flow in the seed suction area. A mechanical model of the rice seed in the seed stirring device was established. The relationships between the seed fluidity and the parameters of the seed stirring device were simulated with EDEM software. The effects of seed fluidity on the seed suction area were analyzed under different seed stirring device parameters. To analyze the influences of different parameters of the seed stirring device on seed stirring and to observe the relationships between different parameters and rice seeds, high-speed photography was used to observe the seed sucking and stirring processes. The super hybrid rice Y-2 You 900 was selected as the test material. The seeding precision was tested at different rotating speeds, negative pressures, and parameters of the seed stirring device. The test results showed that an increase in the diameter and thickness of the seed stirring device was beneficial for increasing the seed absorption rate and reducing the missed seed rate but also increased the rate of multiple-seed sucking and reduced the seeding precision. The optimal parameters of the seed stirring device were a cylinder thickness of 2 mm and a diameter of 5 mm. This study provides a certain reference basis for the seed suction process of a pneumatic seed metering device. Keywords: Agricultural machinery, Precision seeding, Rice sowing, Seed stirring device, Seeder.