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Agriculture is crucial for economic development. Losses in agricultural production were caused by a variety of circumstances, but pests and illnesses are among the most important. The use of plant protection machinery to spray pesticides is still the most effective method of pest control at present. Traditional agricultural sprayers were inefficient and time-consuming, which caused pesticide waste and environmental contamination. In the process of spraying pesticides, farmers are directly exposed to pesticides, which is easy to cause bodily harm or even poisoning. With the steady progress of China's agricultural modernization, robots are widely used in agricultural plant protection work. Intelligent pesticide spraying robots are an effective method to solve the problem of applying pesticides in complex environments such as hills, orchards, fields, and greenhouses, which is more efficient and accurate. Intelligent spraying robot not only saves labor but also reduces the improper use of resources and environmental pollution. It is conducive to our better reaching of the goal of agricultural sustainable development. In this study, the research progress analysis of an intelligent pesticide spraying robot focuses on four respects: mobile chassis design, spraying the device design, navigation technology, and target detection technology. This paper discusses the factors limiting the development of intelligent pesticide-spraying robots for the primary technologies applied to various operation scenarios. Firstly, the mobile chassis design of the spraying robot was analyzed from the ground spraying robot and aerial spraying robot. The study and development of wheel-track composite robot chassis can integrate the advantages of wheeled chassis as well as a tracked chassis, which will be the research trend of ground intelligent spraying robot. Plant protection UAV is unrestricted by terrain, and can be applied to a variety of scenarios, which will be the key orientations for future research. Secondly, the spray devices required by the spraying robot in different spraying scenarios were summarized. It mainly includes an adjustable boom sprayer device, electrostatic spraying device, targeted spraying device, air-assisted spraying equipment, and profile modeling spray equipment. The most commonly used navigation methods are analyzed, including Global Positioning System (GPS) navigation, visual navigation, inertial navigation, multi-sensor fusion navigation, laser radar navigation, odometer, geomagnetic navigation, etc. Additionally, the detection methods of various pesticide spraying robots are evaluated from the perspectives of crop detection and pest detection. The deep learning algorithm can automatically extract the image features of crops, make use of the information, and exactly identify the location of crop pests and diseases, to quickly respond to achieve accurate spraying. Finally, the development trend of intelligent pesticide application robots for precise application is presented. Six requirements or prospects were proposed for the intelligent pesticide spraying robot development in the future, including to improve the response speed of the spraying robot, to improve detection accuracy, to design lightweight chassis, to reduce the development cost of the spraying robot, and to integrated air-ground spraying technology. In conclusion, intelligent and precise application robots have the potential to significantly improve the quality of precision agriculture operations by facilitating intelligent decision-making on operational parameters before actual operation. [ABSTRACT FROM AUTHOR]

Aerial electrostatic spray technology for agriculture is the integration of precision agricultural aviation and electrostatic spray technology. It is one of the research topics that have been paid close attention to by scholars in the field of agricultural aviation. This study summarizes the development of airborne electrostatic spray technology for agricultural use in China, including the early research and exploration of Chinese institutions and researchers in the aspects of nozzle structure design optimization and theoretical simulation. The research progress of UAV-based aerial electrostatic spray technology for agricultural use in China was expounded from the aspects of nozzle modification, technical feasibility study, influencing mechanism of various factors, and field efficiency tests. According to the current development of agricultural UAVs and the characteristics of the farmland environment in China, the UAV-based aerial electrostatic spray technology, which carries the airborne electrostatic spray system on the plant protection UAVs, has a wide potential in the future. At present, the application of UAV-based aerial electrostatic spray technology has yet to be further improved due to several factors, such as the optimization of the test technology for charged droplets, the impact of UAV rotor wind field, comparison study on charging modes, and the lack of technical accumulation in the research of aerial electrostatic spray technology. With the continuous improvement of the research system of agricultural aviation electrostatic spray technology, UAV-based electrostatic spray technology will give play to the advantages in increasing the droplets deposition on the target and reducing environmental pollution from the application of pesticides. This study is capable of providing a reference for the development of the UAV-based agricultural electrostatic spray technology and the spray equipment. [ABSTRACT FROM AUTHOR]

Chemical pesticide residues have posed a great impact on crops and the ecological environment in recent years, as the prevention and control of crop diseases and pests have widely been used in agricultural production. Consequently, an aerial pesticide application technology has become an effective way for plant protection in modern agriculture. The powerful technology is characterized to reduce the numbers and residues of pesticides for the better effectiveness of pesticide application. Alternatively, a high-voltage electrostatic device is often used to charge the spray droplets in an electrostatic spray system. Specifically, the chemical liquid is atomized into droplets near the nozzle to obtain a charge of the same polarity as the nozzle. An electrostatic field is then formed between the nozzle and the crop target under the action of high-voltage static electricity. As such, the droplets of opposite polarity are quickly adsorbed on the front and back of crop targets during the spraying process. Aerial electrostatic spraying is a deep integration of electrostatic spray system and aviation pesticide spraying in precision agriculture. The droplets can quickly be deposited along the power line in the process of aircraft spraying, thereby greatly reducing the drift loss for highly efficient deposition of droplets. Furthermore, the electrostatic spray technology has achieved excellent control effects on crops, fruit trees, and greenhouse vegetables in field tests. The top countries of aerial electrostatic spray technology in the world are the United States and Brazil, in terms of technology usage, and innovation. Particularly, the electrostatic spray technology in the United States has been fully commercialized for the aviation spraying equipment. In addition, an efficient aircraft is highly required for large-scale planting and plant protection in vast arable land and mostly plains in some developing countries. The manned fixed-wing aircraft is mainly used in electrostatic spray systems at present. This review outlined the international development of aerial electrostatic spraying technology to further clarify two main lines of reports at home and aboard, ranging from basic theoretical research to commercialization process. An application level of technology was set to analyze in China. The research on aviation electrostatic spray technology in China has presented a promising increase trend, due mainly to small environmental and topographical impacts in field tests. Moreover, the unmanned aerial vehicle (UAV) has become the most suitable aircraft equipped with an electrostatic spray system after long-term research. However, large research gaps still remained in manned vehicles and lately commercial plant protection UAV, compared with the state-of-the-art electrostatic spray technologies overseas. There were also numerously repeated and invalid studies overlapped in the main parameters in China. Anyway, it is still necessary to delve into the specific interaction mechanism between the process of spraying droplets and the operating parameters. The industrialized development of aviation electrostatic spray system was also reviewed at the end, together with the development prospects. Some suggestions were listed as: (1) The performance of each charge needed to be elucidated in the aerial electrostatic spray system. (2) The measurement technology of charged droplet deposition was highly demanding to accurately evaluate the actual properties of electrostatic spray. (3) Measurement of charge-to-mass ratio was necessary to rethinking using the cutting-edged quantum theories. An ever-increasing demand is coming soon using aviation electrostatic spray system for crop protection. [ABSTRACT FROM AUTHOR]

Orchard spray is a key link to orchard production, due to it occupied nearly 25% of the total workload of orchard management. Moreover, the degree of plant protection mechanization directly affects the economic benefits of fruits. In this review, the orchard characteristic, the general situation of plant protection mechanization and the reasons restricting its development were introduced briefly, in order to clarify the future progress of mechanization technology and equipment for the orchard plant protection in China. The main reason impeding the development of plant protection mechanization can be a large proportion of hilly orchards, including gradient, slope and flat orchard, together with a very complex planting environment. Since the standardized modern orchards are being promoted, the scale is still small, due partly to the extensive management in traditional orchards the high price. Currently, the plant protection mechanization level of flat orchard was 15%, whereas, the hilly orchard was only 7.5%. Therefore, the progress of key plant protection mechanization technologies and equipment was presented in detail, further to improve the mechanization level of plant protection. For example, the pipeline spraying technology and equipment brought good benefits and spraying effects to the hilly orchard, while, the application of air-assisted spraying technology and equipment improved the mechanized operation level of the flat orchard. Electrostatic spraying technology and equipment were especially used to enhance the droplet coverage rate on the back of leaves. While the tunnel spraying technology and equipment increased the droplet density on the canopies, to recovery the droplet that left the target, indicating that it can effectively improve the pesticide utilization. Variable rate spraying technology and equipment were becoming a hot research topic, particularly on the precise control of spray on demand. The core technology of variable rate spraying was target detection, such as ultrasonic detection, laser detection, infrared detection, machine vision methods. The ultrasonic and laser detection methods have achieved the best application. Since 2010, the great development and application of aerial spraying technology and equipment have been widely recognized. Especially, the unmanned aerial vehicle (UAV) of rotor plant protection has become one of the most popular machines with small size, fast flight speed and strong terrain adaptability among the agricultural aerial equipment. In this review, the research state of rotor plant protection UAV in orchard was introduced from three aspects: operation model, down wash flow field, and working parameters. Plant protection equipment can offer some suggestions for the development of plant protection mechanization from these aspects: promoting standardized models of orchard plant, developing stereo spraying technology, promoting specialized and mechanical service model of plant protection, thereby for the intelligent robots of plant protection. [ABSTRACT FROM AUTHOR]

The characteristics of nitrogen fractions in the surface sediments of lakes from Eastern Plain Region, Yunnan-Guizhou Plateau Region, Northeast China Region, Qinghai-Tibet Plateau Region and Mongolia-Xinjiang Plateau Region were investigated and the differences of five lake regions on nitrogen fractionation were discussed. The results indicated that organic nitrogen (N) was the major nitrogen fraction accounting for 76.38-92.02 % of N in sediments. The rank order of average N and N of sediments in five lake regions was: Yunnan-Guizhou Plateau Region > Northeast China Region > Mongolia-Xinjiang Plateau Region > Qinghai-Tibet Plateau Region > Eastern Plain Region. The exchangeable nitrogen had a similar distribution as organic nitrogen in the studied sediments. NH-N is the main exchangeable nitrogen of sediments in the studied lakes except in Lake Qinghai and Lake Yamdrok which contained higher nitrate concentrations than ammonium. Fixed ammonium (N) in the sediments of studied lakes was irregularly distributed with the values ranging from 99.45 to 329.02 mg/kg. TOC was significantly and positively correlated with ammonium, nitrate, N and N, while N was negatively correlated with nitrate probably due to electrostatic attraction between N and nitrate in layers of sediments. [ABSTRACT FROM AUTHOR]