Factors Affecting Droplet Loss behind Canopies with Air-Assisted Sprayers Used for Fruit Trees

Abstract

Air-assisted sprayers are widely employed in orchards, but inappropriate spray parameters can lead to large droplet losses, pesticide waste, and environmental pollution. To investigate the factors affecting the droplet loss of an air-assisted sprayer behind canopies, a two-factor, five-level full experiment was conducted in an actual orchard, where the two factors were the power gradient and foliage area volume density (FAVD). In addition, the location of the sampling point was also considered in the data analysis, including horizontal distance, forward distance, and height. The results show that all factors significantly affected droplet coverage (p-value < 0.01). The droplet coverage showed an increase and then a decrease with an increasing power gradient, and the maximum coverage was measured at power gradient P3 (forward speed: 0.49 m/s, spray pressure: 0.30 MPa, and spray flow rate: 7.13 L/min) or P4 (forward speed: 0.58 m/s, spray pressure: 0.35 MPa, and spray flow rate: 8.44 L/min). The effect of FAVD on droplet coverage had obvious regularity, and this regularity did not change with the power gradient. At different positions behind canopies, the droplet coverage had great differences. The droplet coverage gradually decreases with increasing horizontal distance and height, while increasing with forward distance. This study provides a reference for the air-assisted sprayers to reduce droplet loss, and data support for subsequent research on precision spraying based on FAVD.

Spraying performance of umbrella wind‐field‐type atomization and its application to parameter optimization

“…The wind‐driven sprayers developed according to this technology rely on the formation of air‐assisted airflow along the nozzle direction; this can significantly improve the spray drift resistance and penetration and effectively offset or transform the ambient airflow's influence on the droplet movement state, reducing the pesticide contamination and increasing the efficiency 4–7 . Researchers in China and other countries have conducted numerous experiments on the influencing factors of spray drift and the drift loss process, aiming to reduce the spray drift amount and improve droplet spatial deposit by changing the air‐assisted airflow types and application parameters to clarify the spray drift prevention mechanism 8–11 …”

“…[4][5][6][7] Researchers in China and other countries have conducted numerous experiments on the influencing factors of spray drift and the drift loss process, aiming to reduce the spray drift amount and improve droplet spatial deposit by changing the air-assisted airflow types and application parameters to clarify the spray drift prevention mechanism. [8][9][10][11] In anti-drift sprayers and droplet deposit characteristics, many studies have been conducted by both Chinese researchers and researchers from other countries. 12 For example, a study on the air-assisted flow and air-jet directions effect on droplet deposit found that increasing the air-assisted flow velocity effectively reduced drift.…”

Agricultural Unmanned Systems: Empowering Agriculture with Automation

“…Additionally, the following three papers discuss and research improvements in automated agricultural equipment. Jiang et al [19] discussed issues related to significant droplet loss, pesticide wastage, and environmental pollution caused by improper spray parameters.…”