Pulse Width Modulation – improved spraying technology
Pulse Width Modulation (PWM) is a technology that facilitates individual control of each nozzle on a crop protection sprayer. The technology makes it possible to vary the amount of crop protection product without changing the spray pressure, maintaining a constant droplet size and improving coverage. PWM has become increasingly important in cereal crops, particularly in the application of herbicides, where precision is crucial for effective weed control and reduced chemical use. PWM minimises overlap when spraying, especially on bends or at varying travel speeds. This provides both environmental and cost benefits as less pesticide is needed. With PWM you can switch off individual nozzles or reduce the duty cycle section by section as the sprayer turns. This means under- and over-application is minimised.
PWM technology is also suitable for area specific spraying. For sprayers equipped with field sensor technology (e.g. camera or LIDAR), each nozzle can be switched off until a weed is detected, at which point it opens for application.
PWM offers significant gains in precision agriculture: Reduced use of chemicals, improved coverage and output, reduced risk of drift and environmental impact and better working environment for the operator.
How it works
By regulating the pulse time instead of the spraying pressure, precision spraying is possible regardless of the travelling speed. PWM technology works by rapidly switching each nozzle on and off at a controlled frequency (Image 1). There are PWM nozzles that can open and close with a frequency of 100 times per second. The length of the pulse controls the amount of liquid, allowing for constant pressure and thus constant droplet size.
Additional information
Several manufacturers provide PWM solutions today such as Precision Planting, John Deere, Capsan Ag and Ad Leader. Several companies also offer upgrading of existing sprayers with PWM technology.
The names of the people Christer Johansson, independent advisor on spraying technology. bultaco@hotmail.se (Formally at Swedish Board of Agriculture). Jonas Schön, Advisor Spraying Technology, Swedish Board of Agriculture. jonas.schon@jordbruksverket.se
European Thematic Network for unlocking the full potential of Operational Groups on alternative weed Control
Completed | 2022-2025
- Main funding source
- Horizon Europe (EU Research and Innovation Programme)
- Geographical location
- Greece, Italy, Spain, Latvia, France, Sweden, United Kingdom