Maths to reduce pesticide wastage

Kam Patel reports on speakers at the Institute of Physics congress in Brighton this week

PHYSICS and mathematics are coming to the rescue of agricultural researchers working to develop more efficient and safer methods of applying pesticides to crops.

Peter Walklate of the Silsoe Research Institute said the demand for high-quality food at reasonable prices was high but so was the environmental price. Spraying methods used to safeguard crops may put surrounding areas at risk of unnecessary pesticide exposure.

Of most concern is machinery that uses an air-jet to transport the pesticide to the crop. "Some studies have indicated that 40 to 50 per cent of the spray misses the intended target during the spraying of fruit crops," he said.

Operators are legally obliged to check factors like wind speed and direction to help ensure only target areas are sprayed. But Dr Walklate points out that it is very difficult to check these factors from the back of a tractor and virtually impossible to check wind direction at low wind speeds without appropriate instrumentation on the sprayer.

He is using physics and mathematical equations to model the way pesticide spray is transported to crops, looking both at how droplets move from the spray nozzle into the atmosphere and how the spray reaches and penetrates the crop.

He said: "The aim is to define better operating practices, find better designs for spraying equipment and perhaps move towards a much more 'intelligent' device that can sense the position of its structure to optimise sprayer output."

Dr Walklate is also investigating the efficiency of other measures, such as the use of no-spray zones or putting hedges or windbreaks around orchards.