Pesticides are indispensable in agricultural production. They have been used by farmers to control weeds and insects, and their remarkable increases in agricultural products have been reported. The increase in the world's population in the 20th century could not have been possible without a parallel increase in food production. About one-third of agricultural products are produced depending on the application of pesticides. Without the use of pesticides, there would be a 78% loss of fruit production, a 54% loss of vegetable production, and a 32% loss of cereal production. Therefore, pesticides play a critical role in reducing diseases and increasing crop yields worldwide. Thus, it is essential to discuss the agricultural development process; the historical perspective, types and specific uses of pesticides; and pesticide behavior, its contamination, and adverse effects on the natural environment. The review study indicates that agricultural development has a long history in many places around the world. The history of pesticide use can be divided into three periods of time. Pesticides are classified by different classification terms such as chemical classes, functional groups, modes of action, and toxicity. Pesticides are used to kill pests and control weeds using chemical ingredients; hence, they can also be toxic to other organisms, including birds, fish, beneficial insects, and non-target plants, as well as air, water, soil, and crops. Moreover, pesticide contamination moves away from the target plants, resulting in environmental pollution. Such chemical residues impact human health through environmental and food contamination. In addition, climate change-related factors also impact on pesticide application and result in increased pesticide usage and pesticide pollution. Therefore, this review will provide the scientific information necessary for pesticide application and management in the future.

https://www.mdpi.com/1660-4601/18/3/1112/pdf

Agriculture Development, Pesticide Application and Its Impact on the Environment.

Agricultural aerial spraying is an effective guarantee to achieve food security and ecological security in China.In this article,the research status of agricultural aerial spraying technology in China was reviewed and summarized.Three aspects such as models of agricultural airplane,key technologies of aerial spraying and supporting equipments in aerial spraying were elaborated,and then the prospect of China's agricultural aerial spraying was expected through comparing the current situation of aerial spraying with developed countries.It will provide progress reference for scientific research and development of domestic research institutions and enterprises.

Current Status and Future Trends of Agricultural Aerial Spraying Technology in China

Numerical simulation of the downwash flow field and droplet movement from an unmanned helicopter for crop spraying

High-accuracy, high-resolution downwash flow field measurements of an unmanned helicopter for precision agriculture

Although drift is not a new issue, it deserves further attention for Unmanned Aerial Spraying Systems (UASS). The use of UASS as a spraying tool for Plant Protection Products is currently explored and applied worldwide. They boast different benefits such as reduced applicator exposure, high operating efficiency and are unconcerned by field-related constraints (ground slope, ground resistance). This review summarizes UASS characteristics, spray drift and the factors affecting UASS drift, and further research that still needs to be developed. The distinctive features of UASS comprise the existence of one or more rotors, relatively higher spraying altitude, faster-flying speed, and limited payload. This study highlights that due to most of these features, the drift of UASS may be inevitable. However, this drift could be effectively reduced by optimizing the structural layout of the rotor and spraying system, adjusting the operating parameters, and establishing a drift buffer zone. Further efforts are still necessary to better assess the drift characteristics of UASS, establish drift models from typical models, crops, and climate environments, and discuss standard methods for measuring UASS drift.

/pdf/characteristics-of-unmanned-aerial-spraying-systems-and-3rdx8efv.pdf

Characteristics of unmanned aerial spraying systems and related spray drift: A review

Numerical simulation of airflow field from a six–rotor plant protection drone using lattice Boltzmann method

Accurate measurement of the downwash flow field of plant protection unmanned aerial vehicles (UAVs) is essential for analyzing the spatial distribution of droplets. To realize on-line rapid detection of the downwash flow field of a multi-rotor UAV, a flexible polypropylene detection device based on the principle of full bridge strain effect was proposed. Its performance principle was based on the physical deformation caused by wind pressure. The Fluid Flow and Static Structural modules of ANSYS 16.0 finite element software were used to simulate one-way fluid-solid coupling interaction. The surface of the resistive strain gauge embedded in the flexible detecting structure responded well to wind speed variation, hence it was suitable for downwash airflow wind field detection. By solving the strain force on the surface of the flexible detection structure, the length and layout of the grating wire of the strain gauge on the surface of the flexible detection structure were optimized. Meanwhile at 4 m·s-1 wind speed, the output voltage at varied bridge flexible acquisition systems in the acquisition card was measured. Results indicated coefficient of variation of 3.67%, 1.63% and 1.5%, respectively, which proved the good data acquisition consistency of the system. Through calibration test, the regression equation for the relationship between output voltage and wind speed for three unique sensor signal measuring circuits was established. The determination coefficients R2 for single bridge, half bridge and full bridge circuits were 0.9885, 0.9866 and 0.9959, respectively. In conclusion, by applying the multi-rotor plant protection UAV test platform, the results indicated the maximum relative error of the wind speed at each sampling point of the system at 1.0 m altitude was below 5.61%. Simulated and measured value had an RMSE maximum error of 0.1246 m·s-1. Moreover, downwash airflow detection not only has high accuracy but also has high sensitivity. Thus, there is convenience and practicability in the plant protection offered by this approach. The rapid measurement of UAV wind field and the established two-dimensional wind field model can provide a basis for precise application of agricultural aviation.

/pdf/design-of-uav-downwash-airflow-field-detection-system-based-25u5udnkzo.pdf

Design of UAV Downwash Airflow Field Detection System Based on Strain Effect Principle

To minimize pesticide dosage and its adverse environmental impact, Unmanned Aerial Vehicle (UAV) spraying requires precise individual canopy information. Branches from neighboring trees may overlap, preventing image-based artificial intelligence analysis from correctly identifying individual trees. To solve this problem, this paper proposes a segmentation and evaluation method for mingled fruit tree canopies with irregular shapes. To extract the individual trees from mingled canopies, the study fitted the projection curve distribution of the interlacing tree with Gaussian Mixture Model (GMM) and solved the matter of segmentation by estimating the GMM parameters. For the intermingling degree assessment, the Gaussian parameters were used to quantify the characteristics of the mingled fruit trees and then as the input for Extreme Gradient Boosting (XGBoost) model training. The proposed method was tested on the aerial images of cherry and apple trees. Results of the experiments show that the proposed method can not only accurately identify individual trees, but also estimate the intermingledness of the interlacing canopies. The root mean squares (R) of the over-segmentation rate (Ro) and under-segmentation rate (Ru) for individual trees counting were less than 10%. Moreover, the Intersection over Union (IoU), used to evaluate the integrity of a single canopy area, was greater than 88%. An 84.3% Accuracy (ACC) with a standard deviation of 1.2% was achieved by the assessment model. This method will supply more accurate data of individual canopy for spray volume assessments or other precision-based applications in orchards.

Interlacing Orchard Canopy Separation and Assessment using UAV Images

The invention relates to the technical field of plant protection unmanned aerial vehicles, in particular to a self-adaptive sprinkling width regulating device and method for a multi-rotor plant protection unmanned aerial vehicle The self-adaptive sprinkling width regulating device is fixedly connected right under each rotor supporting rod of the multi-rotor plant protection unmanned aerial vehicle in a detachable manner; the self-adaptive sprinkling width regulating device comprises a housing, a nozzle and an automatic control system, wherein the nozzle faces towards the ground; the nozzle and the housing form a sliding connection and can freely move in the length direction of the housing; a laser sensor facing towards the ground is arranged on the nozzle; and the nozzle regulates the moving position in a self-adaptive manner by using the automatic control system according to the edge contour of the section of maximum crown diameter of a fruit tree According to the self-adaptive sprinkling width regulating device and method for the multi-rotor plant protection unmanned aerial vehicle, the sprinkling width is regulated in a self-adaptive manner with the edge contour of the sectionof the maximum crown diameter of a fruit tree, the pesticide application is accurate, the drifting of a pesticide liquor to a non-target area is reduced, the soil pesticide residue is reduced, the fog drop distribution uniformity is improved, the pesticide utilization rate is increased

Self-adaptive sprinkling width regulating device and method for multi-rotor plant protection unmanned aerial vehicle

The invention belongs to the field of fruit garden profiling spraying, and particularly relates to and provides a fruit tree profiling sprayer based on a laser detecting and image processing technology and a method. The fruit tree profiling sprayer comprises a vehicle body chassis, a pesticide applying device, an image collecting device, a laser detecting device and a data processing control system. Different profiling spraying modes are selected according to the death rate and morbidity rate of fruit trees in a fruit garden. When the death rate and morbidity rate of the fruit trees in the fruit garden are low, the real-time profiling spraying mode is selected; when the death rate and morbidity rate of the fruit trees in the fruit garden are high, the centered profiling spraying mode is selected. The profiling cost is low, variable detection is realized, and the profiling accuracy can be improved.

Zhang Hao

Papers

Numerical simulation of airflow field from a six–rotor plant protection drone using lattice Boltzmann method

Design of UAV Downwash Airflow Field Detection System Based on Strain Effect Principle

Interlacing Orchard Canopy Separation and Assessment using UAV Images

Self-adaptive sprinkling width regulating device and method for multi-rotor plant protection unmanned aerial vehicle

Fruit tree profiling sprayer based on laser detecting and image processing technology and method