Levels of nitrogen in Poole’s harbour and waterways continue to rise, despite farmers using less of the chemical to fertilise their crops.
Increasing amounts of nitrogen are causing more algae to grow and problems for wildlife with “the majority of nitrogen in Poole Harbour generated from agriculture” said a spokesperson for Poole Borough Council.
Disruption to ecosystems
Nitrogen is essential for plant growth, but too much can change the way an ecosystem functions. Environmental scientist, Dr Dan Franklin said: “One thing that’s been noticed in the harbour is the big increase in the amount of ‘green seaweed’ or what we call macroalgal blooms.
“That’s one of the things that regulators and governments are most worried about – the effect that this organic matter has on the ability for shorebirds to feed.”
Initiatives to improve waterways
Despite nitrogen levels increasing, farmers in the area have been using less of the chemical thanks to the Poole Harbour Catchment Initiative. “Farmers have gone a long way to improving soil and nutrient management efficiencies in the Poole Harbour catchment area” said Robert Baxter, NFU Group Secretary for Wimborne.
The Poole Harbour Catchment Initiative’s aim is to achieve sustainable farming that supports healthy rivers and groundwater in the area – the initiative is supported by a number of organisations and local farmers.
Bournemouth’s Berry Hill Farm is one local farm supporting the drive to use less nitrogen enriched fertilisers. Farm owner Jim Hooper, 51, said: “We are using far less nitrogen than we would have forty years ago – it was being overused.”
As Mr Baxter explains, there is still room for improvement. He said: “As the understanding of the impact and nature of diffuse pollution improves, so must the efforts of farmers improve.”
Not a quick fix
Dr Franklin said: “This can’t be fixed quickly because it’s a legacy issue – it takes nitrates something like forty years to get from the field to the harbour.
“Poole Harbour is a magnificent ecosystem and lots of people want to use it for different purposes, so it’s very important that we continue to work together to try and improve its management.”