Spray distribution from ground-crop sprayers

Abstract

As part of a procedure for testing ground-crop sprayers, methods were devised for measuring the distribution of the spray over the width of the boom and in the direction of travel. In the lateral direction, a mobile spray patternator 8 ft wide was used to measure the distribution, and to test nozzles according to B.S.2968.1 The effect of boom height on distribution was much greater for nozzles producing rectangular spray patterns than for those with triangular patterns. The nozzle performance required by the British Standard did not ensure even spraying, even at the optimum boom height. In the direction of travel, the effect of bumpy ground on spray distribution was assessed in an indoor test. The tractor was driven over a block 2 in high and spray application rate was measured at the end of the boom. When a sprayer with a flexible boom and hollow-cone nozzles was tested at 4 mile/h, the application rate varied between 72 and 128% of the mean. A sprayer with a stiff boom and fan-spray nozzles gave variations between 75 and 142% at 3 mile/h. This was due to horizontal vibrations in the outer sections of the boom; when these vibrations were reduced more even spraying was achieved.