Design and experimental assessment of a field-spraying system with nozzles employing reciprocating up-and-down movements.

Abstract

Proper dense planting pattern can improve rice yield. For an ordinary boom sprayer, it is still difficult for the droplets to penetrate the dense rice canopy even if an auxiliary airflow is used, especially in the middle and late growth stages. The deposits of droplets at the bottom of the rice plants are typically small. In this study, a spraying system was designed with nozzles creating reciprocating movements into the middle and bottom of the rice canopy. An air pump provided power to push the nozzles up and down. A time relay and a solenoid valve were used to control the cycle and stroke of the reciprocating movement. At different growth stages of rice, comparative tests were conducted between the air-assisted spraying pattern (without reciprocating movement of nozzles) and the reciprocating movement spraying pattern (without auxiliary airflow). The results showed that for the reciprocating movement spraying pattern, the droplet number densities in the middle and bottom of the rice in the late growth stages increased from 78 to 124/cm2 and from 19 to 121/cm2 , respectively, and the coverage rates increased from 13.34% to 24.26% and from 3.61% to 21.21%, respectively. The droplet depositions increased from 0.603 to 1.139 mg cm-2 and from 0.095 to 1.001 mg cm-2 , respectively. This spraying pattern can increase droplet deposits at the middle and bottom of the crop and improve uniformity. © 2023 Society of Chemical Industry.