Abstract:

Water sensitive papers (WSP) are often used to determine drop characteristics in spray applications. Since the droplets that come into contact with the surface of the WSP create a stain, the spray characteristics can be determined by the image processing method. The aim of this study is to bring a standard approach to drop sampling, eliminate the factors based on operator preference in image processing, and determine the spray characteristics by statistical methods. A spray simulator was used for drop sampling and low volume (80 l ha-1) spraying applications were performed under controlled conditions. The trials were repeated 9 times and the collected WSP samples were scanned and the image processing and stain analysis were performed. The thresholding level of the WSP images is determined according to the average grayscale level. WSP samples with a surface coating rate above 30% were not included in the analysis. Stains with a circularity factor of less than 0.8 were eliminated to determine the stain size. Macro module was created to determine the drop characteristics. The spherical diameter of the drops was estimated according to the spreading factor of the spots. A descriptive statistical method was used to determine the spray characteristics and the calculations were made by creating 20 droplet diameter classes. The average droplet diameter (D10, D20, D30 and D32), volumetric distribution of droplets smaller than 100, 150, 200 and 250 µm (V100, V150, V200 and V250), volumetric diameters (DV0.10, DV0.25, DV0.50, DV0.75 and DV0.90), droplet spectrum relative span factor (RSF), droplet uniformity coefficient (R) and droplet uniformity ratio (H) were calculated. When the repeated experiments were compared between themselves, it was observed that there was a great harmony between the factors that defined the change of droplet diameters, the spread of the droplet spectrum, cumulative distribution curves and droplet homogeneity. The correlation analysis found a positive correlation between D32 and DV0.50 diameters. As the drop diameter increased, the RSF value decreased. The correlation between r and H values was found to be very important statistically and it was determined that there was a negative correlation between them.

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