A sprayer boom swinging through a headland turn runs fast on the outside and nearly stops on the inside. Conventional pressure-based rate control answers by changing pressure, which changes droplet size, which is how a legal application becomes a drift complaint from the neighbouring field.
Vossmark's SP140 pulses each nozzle individually at 30 hertz and varies the duty cycle rather than the pressure. Rate follows ground speed nozzle by nozzle across the 36.5-metre boom while pressure, and therefore droplet spectrum, stays where the label requires.
Turn compensation, measured
In Vossmark's trials, coefficient of variation across the boom through a 90-degree headland turn fell from 23% to 6%. The company is careful to note that pulsing does not reduce drift on its own; holding a coarse droplet spectrum does, and pulsing is what makes that possible at variable speed.
The system also closes nozzles individually for section control down to 380 millimetres, which on point rows and irregular field edges Vossmark estimates saves 2% to 4% of chemical.