Phosphate, key to food production, is choking waterways, but a new sponge-like material returns it to the soil for crops

It is one of the least appreciated substances on the planet and its misuse is now threatening to unleash environmental mayhem. Phosphorus is a key component of fertilisers that have become vital in providing food for the world. But at the same time, the spread of these phosphorus compounds – known as phosphates – into rivers, lakes and streams is spreading algal blooms that are killing fish stocks and marine life on a huge scale.

It is a striking mismatch that is now being tackled by a project of remarkable simplicity. The company Rookwood Operations, based in Wells, Somerset, has launched a product that enables phosphates to be extracted from problem areas and then reused on farmland.

The reserve in Geltsdale in the north Pennines has been expanded by a third after RSPB buys land

It covers more than 50 square kilometres of blanket bog, heath, meadows and woodland and rises from a valley floor to the 640m summit of Cold Fell in the north Pennines. This is RSPB Geltsdale, and it will now be the organisation’s largest English bird sanctuary when the society announces this week that it has bought land that expands the existing reserve by a third.

“This is going to be a reserve on a different scale from many of our other sites in England,” said Beccy Speight, the RSPB’s chief executive.