THE TRANSFORMATION OF SPATIALLY DETERMINED DROP SIZES TO THEIR TEMPORAL EQUIVALENTS FOR AGRICULTURAL SPRAYS

A statement of formulation effects on atomization by agricultural nozzles is already a requirement for the registration of a new chemical or formulation in the USA and parts of Europe. The laser-based instruments used for obtaining such data can be divided into two types: those that analyse the sample signal either spatially or temporally. It is known that for agricultural nozzles operating from ground rigs without air assistance, spatial measurements of the spray cloud overestimate the small drop component. Consequently, spatially determined data can be used to separate different atomization methods and formulations on a qualitative, but not a quantitative, basis. Data acquired from temporal analyses of the drop spectra produced by agricultural nozzles using an Aerometrics PDPA 100-1D particle analyser are presented. The results show that for a given nozzle, there is a ''coefficient'' for each of the common spray descriptors (e.g, arithmetic mean, volume median diameter, etc.) whereby the spatially derived descriptor can be converted to its temporal equivalent, for a wide range of atomization pressures and formulations. Such ''coefficients'' would render spatially determined data more applicable to solving the problems involved in applying agrochemicals, However, these ''coefficients'' would have to be obtained in a manner applicable to spatial sampling methodology.