Dutch research on spray drift gives flexibility

Spray drift reduction techniques used in The Netherlands offer growers a greater number of options to help keep pesticides out of watercourses, helping the sector meet its long-term aim of halving agrochemical use.

In The Netherlands, air induction nozzles capable of reducing spray drift by as much as 90% were needed for certain products and tasks, said Jan van de Zande, an expert in spray drift technology at Wageningen University.

The same nozzles were available for use in the UK, but were less popular with growers, said Syngenta application specialist Tom Robinson. “They make a very blobby spray.”

Mr van de Zande explained how the Dutch use a drift reduction classification table offering different opportunities to reach the necessary classification: 50%, 75%, 90% and 95% reduction compared with a 110-04 reference nozzle.

The system takes into account a number of factors, including nozzle type, boom height and crop type, with or without air assistance and mechanical drift reduction systems, such as the Crop Surfer.

Mr van de Zande said the classification table was part of a long-term plan in the Netherlands to reduce spray drift and emission of pesticides in the water by at least 90% and the use of agrochemicals by 50%.

Under the Water Pollution Act, Dutch sprayer operators must use low drift spray techniques – at least 50% spray drift reduction – for a minimum of 14m from the outside swath, with a maximum boom height of 50cm above crop canopy, and the use of a border nozzle on the end of the boom.

Buffer zones for spraying cereal crops are 25cm from the crop edge, 50cm for sugar beet and maize crops and 1.5m for potatoes and flower bulbs.

“These are the minimum requirements, but they can be widened and become more severe depending on the toxicity of the product that you’re using,” noted Mr van de Zande.

Mr Robinson added: “I think the Dutch system offers more flexibility, giving more options for achieving your drift reduction requirements.”

In the UK, a three-star LERAP nozzle offers 75% sprayer drift reduction, so that sprayer operators can reduce the distance between the end of the boom and field margin to 1m, said Mr Robinson.

“For full doses, if you have a LERAP category B product, you can bring your buffer strip down from 5m to 1m if you use a three-star LERAP nozzle operated at the approved pressure, boom height and forward speed,” he explained.

“This will give you a 75% drift reduction compared with a 110-03 fan jet at 3 bar pressure.”

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