Alternative calculations to show how much nitrogen-based pollution in environmentally-sensitive areas is down to farming, suggest that farms are responsible for 25% not the official estimate of 46% of the problem.

The figures were presented by the farming lobby on Wednesday to counteract official figures which farmers say are exaggerated.

However, experts from the Dutch public health institute RIVM were quick to dismiss the new estimates, drawn up by the Mesdag-Zuivelfonds, saying they had included lakes and waterways as well as land in the calculations.

‘The Mesdagfonds would appear to have looked at all 160 nature reserves in the Netherlands, not just the 118 reserves which are sensitive to nitrogen-based pollution,’ the RIVM’s Kees van Luijk said.

‘If you are including water, you are also including the massive area covered by the IJsselmeer lake, for example,’ he said. ‘But nitrogen which lands on water is gone the next day.’

Farmers say they are being made to shoulder too much of the responsibility for cutting nitrogen-based pollution, which primarily comes from the livestock industry.