Effects of droplet size and spray volume parameters on droplet deposition of wheat herbicide application by using UAV

Abstract

With the characteristic of flexible and precise, unmanned aerial vehicles (UAVs) for low volume applications are increasing substantially and quickly around the globe. However, little attention has been paid to the study of wheat herbicides with UAV, especially the research on the spray volume and droplet size of the herbicide sprayed by UAVs. The objectives of this study were to compare the droplet deposition from a typical commercial UAV under four different spray volumes of 7.5 L/hm 2 , 15.0 L/hm 2 , 22.5 L/hm 2 , and 30.0 L/hm 2 and three different volume median diameter (VMD) of 150 μm, 200 μm, and 300 μm during winter wheat weeding period. DepositScan software was used to analyze droplet deposition parameters including the percentage of spray coverage and the number of droplets in various sampling positions. The test results showed that the droplet deposition was effected by each factor and their interactions. When the spray volume was 7.5 L/hm 2 , the effect of VMD on the percentage of spray coverage was not significant. However, these variation rules were changed to smaller droplets with greater coverage when the spray volume higher than 15.0 L/hm 2 . In all treatments, the number of droplets increased with decreasing VMD or increasing spray volume. The maximum percentage of spray coverage and the number of droplets that were achieved under the VMD of 150 μm and the spray volume of 30.0 L/hm 2 were 12.8% and 40.0 droplets/cm 2 , respectively. The variation coefficients of the percentage of spray coverage and the number of droplets were 29.0%-73.3% and 20.2%-54.1%, respectively. The most uniform deposition was achieved under the spray volume of 15.0 L/hm 2 and the VMD of 150 μm. The results revealed the effect of droplet size and spray volume parameters on droplet deposition, which was useful for guiding farmers on how to use UAVs for weeding in winter wheat fields.

Aeronave Remotamente Pilotada (RPA) para aplicação de agrotóxico

“…Ahmad et al (2020) em um experimento, empregando-se um veículo aéreo não tripulado, relatam porcentagens de cobertura de 36,19% em seu trabalho, porém empregaram-se um maior volume de calda, o que influenciou diretamente na porcentagem de cobertura. Shan et al (2021) em aplicações com um veículo aéreo não tripulado, também observaram que a porcentagem de cobertura aumentou com o aumento do volume de calda. Com um volume de calda de 7,5 L ha -1 em uma velocidade de 10,8 km h -1 apresentaram uma porcentagem de cobertura de 2,7%, já com uma vazão de 15 L ha -1 a porcentagem de cobertura chegou a 4,6%.…”

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

“…The drift of herbicides generally produces a higher impact on the environment than for fungicides and insecticides. In the early stage of UASS application, the blind use of herbicides to affect non-target organisms is a common strategy ( Shan et al, 2021 ). While Japan developed drone sprayers earlier, herbicides were processed in the form of granules specifically for drone application according to the properties of drone aircraft spraying ( Yuan et al, 2018 ).…”

Evaluationof compact air-induction flat fan nozzles for herbicide applications: Spray drift and biological efficacy

“…Effective spray deposition and drift reduction of herbicide applications have come to the forefront all over the world (Alves et al, 2017;Butts et al, 2019;Oliveira et al, 2019;Carbonari and Velini, 2021). A number of previous studies have shown that droplet size plays an important role on spray deposition and drift behavior (Ennis and Williamson, 1963;McKinlay et al, 1974;Lake, 1977;Knoche, 1994;Jensen et al, 2001;Wilkerson et al, 2004, Shan et al, 2021. In most cases, smaller spray droplets provide greater coverage and deposition of the target tissue, thus maximizing herbicide activity.…”