It was a wonderful sunny weekend in Dorset, and we went for a cycle ride along the Frome valley. Returning from our picnic we cycled along the edge of a field. The field was mostly rye-grass but along the very edge between the path and the hedged stream was a narrow strip of grassland – with some flowers and butterflies that had were absent from the rest of the field.
As I tried to cycle along the very narrow path (it was a bridleway) I noticed little white balls on the path. I realised these were prilled nitrogen – little balls of fertiliser spread by the farmer using a spinner on the back of his tractor. There weren’t many – they couldn’t have added up to more than a few grammes over a square metre of grassland. But that’s all it takes to provide the fertility for the grass to grow a bit lusher than it would otherwise have done, to provide more grass for his livestock. The extra nitrogen gives a competitive advantage to the rye-grass, at the expense of the wildflowers.
By coincidence this morning, a major report by the Centre for Ecology and Hydrology was published, on the environmental impact of this “reactive” Nitrogen. This research has found that the cost to Europe of all this extra Nitrogen is between £60 billion and £280 billion pounds a year (for comparison the entire Common Agricultural Policy costs Europe around £45 billion a year). The cost is calculated by analysing the cost of climate change, cleaning nitrates from water, deaths from air pollution and even the loss of biodiversity that results in an environment awash with excess nitrogen.
The cost of this excess Nitrogen – to biodiversity and our relationship with nature – is not just that which can be measured in pounds or euros. It’s also the difference in the way we feel when we see (hear, smell) a bright green field of rye-grass, or one filled with flowers, bees and butterflies.