Male visitors to the massive Sail maritime festival in Amsterdam later this month are being asked to pee at special locations so their urine can be turned into fertiliser.

The city’s water boards hope to collect 100,000 litres of pure urine which can be distilled to extract phosphates, the Parool reports on Friday. Phosphates, which can also be mined underground, are used to help plants and crops grow more quickly.

Two collection points are being set up – one on the De Ruyterkade and one on the Piet Heinkade, the Parool says.

Male visitors are being targeted because it is easier to collect uncontaminated urine from them, spokeswoman Danielle van Gerven told the paper.

‘Phosphates are in short supply and that is why we are trying to show people that human waste need not be treated as rubbish,’ she said.

Donors can choose which of three green projects in Amsterdam should get the fertiliser made from Sail urine.