Development of GIS-based chemical distribution maps from sprayer performance data

Pesticide application is an essential practice on farms in Kentucky where glyphosate resistant crops and no-till farming strategies are becoming more popular. Off-rate pesticide application errors are the result of incorrect concentrations applied to an area of the field and may result from velocity changes along the spray boom while the sprayer is turning, pressure changes across the width of the spray boom, and changes in effective boom height due to undulating terrain. In an attempt to estimate potential errors resulting from sprayer turning movements, a method was developed to compare the differences in application areas between control sections across the spray boom. The area covered by the two center boom control section positions was considered the "target rate" and the difference in these areas and the remaining control sections were compared to determine errors in coverage areas. The results of the analysis conducted on three irregular shaped fields (containing impassable grassed waterways) indicated that a substantial portion of the fields (14-24%) could have been applied well above or below the target application rate +/- 10%. The implication of this is that producers may be under and over applying chemicals to fields where excessive amounts of turning are required during application.