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

Background

A dense rice‐planting pattern is currently used. 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 were 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 the 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).

Results

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/cm² to 124/cm² and from 19/cm² 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 mg/cm² to 1.139 mg/cm² and from 0.095 mg/cm² to 1.001 mg/cm², respectively.

Conclusions

This spraying pattern can increase droplet deposits at the middle and bottom of the crop and improve uniformity.

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