Foam markers utilize an air pump to pressurize a tank containing the foaming agent, thereby causing the agent to flow to the accumulating chamber. The foam collects in this chamber until the accumulated mass overcomes surface tension, causing a foam blob to fall to the ground. Most often the foam accumulators are placed at the ends of the applicator boom, or alternately at the center of the applicator when booms were not utilized, as is the case with spinner disk granular applicators. Equipment operators use the foam blobs left on the field surface as a navigation aid to know where the applicator has been. GPS-based lightbars allow the operator to select an AB line by identifying start and end points.
Software allows the user to specify the sensitivity and distance between parallel passes.
A sequence of LEDs light up to guide the driver as steering corrections are warranted. The expectation is that either foam markers or lightbars will improve the quality or application by improving the quality of spacing between parallel passes. The purpose of the work detailed in this manuscript is to assess the perceived improvement in application accuracy. The lower the CV the more uniform the distribution pattern. Details, such as test setup, collection devices, test procedure, distribution, effective swath width, determination of application rates, are given clear definitions in the test procedure section in the standard.