Catching Method of Spray Droplet and Distribution of Spray Droplet Size in Greenhouse Low Volume Application

Abstract

This study was done to compare numbers of spray droplets and their sizes resulting from the difference between wettable powder and emulsifiable concentrate, the difference between non-coated slide glasses and polyethelen coated paper on catching spray droplets, the difference between black-white film and colored one on photographing, and the difference between the distance from the nozzle in the green house low volume application.
The data obtained here were summarized as follows.
(1) There was a significant difference between numbers of spray droplets caught on non-coated slide glass and those on polyethelene-coated paper. The numbers of the former were about 30 droplets per 6×10⁴(μm)² more than that of the later.
(2) Maximum frequency diameter of droplet was 1μm, and the frequency distribution of 1μm in diameter was higher according as the slide glasses or papers were away from the nozzle, and became 50% at 34m from the nozzle. There was no significant difference between the catching materials of spray droplets, or between photographings.
(3) By analyzing coverage ratio statistically, the materials of catching spray droplets, the characteristic of agricultural chemicals and the distance from the nozzle were significant. Coverage ratio on non-coated slide glass was higher than that on polyethelene coated paper.
Coverage ratio of sprayed wettable powder was higher than that of emulsifiable concentrate. Coverage ratio at 25m apart from nozzle decreased remarkably.
(4) Mean diameters of droplets were d₁=2-3μm, d₂=4-6μm, d₃=6-10μm, d₆=20-36μm respectively.
There was a significant difference only between wettable powder and emulsifiable concentrate spraying, but no significant difference between the catching materials or between photographings.
(5) The coefficient on uniformity of droplet size was 10-30% within 10m from the nozzle and 30-50% beyond 20m.