Applications Of Modern Pesticide Aerial Application Technology And The Impact On Rice Quality

Considering the difficulty of pest control in paddy fields, and the issue of backward in pesticide aerial application technology, this paper integrated National 863 project-"Research on very-low altitude,and low volume aerial application techniques in paddy fields and equipment invention", Southern Plains Agricultural Research Centerof U.S. Department of Agriculture project-"Aerial application research for efficient crop production", and an international cooperation project in Jiangsu Province-"Aerial spraying drift predicting techniques";explored the key technology of pesticide aerial application with UAV, the law of aerial spraying droplet drift deposition, the characteristics of settlement and attachement of pesticide on rice plants, and low volume high concentration spray formulations for rice safety; developed a GPS-based unmanned aerial vehicle (UAV) for pesticide application with indoor and field spraying test verification; establisheda model of predicting aerial spraying drift; exploredthe influences of low volume high concentration aerial application on rice quality in order to provide technical support on the development of aerial safety specification. The paper related content has been accomplished at Nanjing Agricultural University, Nanjing Agricultural Mechanization Institute, and the Southern Plains Agricultural Research Center, U.S. Department of Agriculture, Texas.The main content of the full text is as follows:1.Rice plants and pesticide spraying characteristics. (1)Studied on the surface wetting and spreading propertiesof nine verities of conventional rice pesticides and formulations;determined the critical surface tension of the blades of the three rice varieties, the liquid surface tension, the critical micelle concentration, and paddy utilization withdifferent surface tension of the solution. The results show that:when spraying a solution of the surface tension is less than the critical surface tension of the rice leaves, it can effectively increase the deposition efficiency of the solution at the surface of the rice plants; (2)Studied on the impact of conventional rice pesticides and formulations on rice safety. The application resultsof the six concentration gradients of each nine kinds of conventional pesticides medicament in the three rice varieties show that:different rice varieties had different resistant to the pesticides; in terms of high concentration spraying operation, chlorpyrifosgenerated a certain degree of phytotoxicity, and Imidaclopridproduced injury on some varieties; others were safe. Because of the differences of ingredients and technology in the processing of pesticide formulations, it is necessary to screen conventional pesticides before spraying.2.Law of low amount of spray droplet and spray deposition. (1) Investigated the atomization mechanism of a rotary atomizer, the relationship betweenthe diameter of the fog grainand spinning speed, and the relationship between spinning speed and droplet velocity field; (2) Studied on the drift pattern of droplets from 3-5 meter high to the target crops in both indoor wind tunnel simulation and field testing, and optimized the operating parameters, such as the droplet diameter, spray volume, operating speed, operating altitude; (3)Designed wind field and test method of aerial application with unmanned rotorcraft, and studied on the downwash airflow field of the unmanned rotorcraft; (4) Established dynamic simulation modelof aerial spraying using unmanned helicopter based on CFD to predict droplet drift and deposition range in actual application based on ambient temperature, wind speed, spray volume, flight speed, flight altitude, and other parameters.3. Development ofGPS-based unmanned aerial spraying equipment. The system mainly consists of the flight control host, airborne radio, onboard GPS, route planning PC and the ground station. A high precision,automatic control UAV system based on GPS auto navigation was designed. The route analysis show that when the speed of side wind was between 3～4m/s, the deviation rms of 12 flying routesranged from 0.3 to 0.7m/s. It means that the UAV actual flight routes matched the scheduled routes. The experiment on multi- amplitude spray shows that the spray uniformity coefficient of variation was 0.25 when spray amplitude was below 7 m. The system was developed using the C language and MATLAB to control route planning and real-time display software. These functions, planning field margin and flight routesautomatically, estimating area of farmland, real-time display of the flight path, and fixed-point precision spraying, can be accomplishedby jointing the control system of the UAV and the airborne embedded spraying system.4.Efficacy of pest and disease control treatment applied using GPS-based UAV spraying. The check was given at the different growth stages of rice, tillering stage and booting stage,in the field. The test results show that:(1) at tillering stage,aerial spraying of planthoppers and leafroller has better leaf protection than conventional spraying, especially in the 10 days after application; (2) at booting stage, we tested reduced pesticide amount by 10%,20%, and 40%, and different flight altitudes. The field efficiency check shows that in the prevention and control of rice planthoppers, the difference was not evident; the effect of the prevention leaffolder was better than traditional spraying operations andaerial spraying can be effective in reducing the application amount of pesticides; (3)Flight altitude was correlated withthe efficacy of prevention of leafroller, but not with the prevention or control of rice planthoppers. Overall, low capacity air spraying operationsincreased deposition of liquid in the riceand reduced the loss of pesticides in non-target areas. It is positive significance for pesticide reduction.5. Effect of pesticide aerial application on rice quality. We studied onaerial application on two rice varieties using conventional spraying methods with traditional large flow (50L/acre) large droplet (≥300μm) and low flow(1L/acre) fine droplets (≥200μm). Undersame cultivation, management conditions, the effect of these two methods on rice production were investigated. Studies have shown the pesticide abatement time on the rice leaveswere different in terms of different rice varieties. From the measurement result of rice pesticide residues one month after application, the residues of three pharmaceutical by aerial application were all below the national standard, and additives pharmacy had no effect on the results. Conventional spraying of 150% of the registered, the residual quality on the rice was not able to meet the safety standard. The results of the dynamic mechanical thermal analyzer show that rice treated with aerial spraying of chlorpyrifos has higher hardnessthan those treated with conventional spray. The viscoelastic properties of rice were not different between aerial applications of tebuconazoleand conventional spraying. The results of X-ray diffraction on rice show that either aerial applicationor manual application has an impact on the microstructure of the rice grain; as the concentration increases, its impact will be a slight increase. The impact on the microstructure of the rice grain by aerial application was less than conventional spraying.