‘High Fertiliser Use Reduces Pollinators and Biodiversity’
Research from the world’s longest ecological experiment highlights how the use of high levels of fertilisers in agricultural grasslands significantly reduces biodiversity. The study, conducted on Rothamsted’s Park Grass since 1856, revealed that heavy application of nitrogen, phosphorus, and potassium fertilisers decreased the number of flowers by fivefold and halved the population of pollinating insects.
The findings, published in the journal npj Biodiversity, demonstrate that bees were particularly affected, with plots treated with chemical fertilisers showing nine times fewer bees than untreated plots. Dr Nicholas Balfour of Sussex University, who led the research, explained that high fertiliser levels allow fast-growing grasses to dominate, outcompeting flowers and diminishing habitats for pollinators. “This creates cascading effects up the food chain,” Balfour stated.
Pollinators, including bees, butterflies, hoverflies, and wasps, were monitored across 18 test plots with varying fertiliser treatments. The average fertiliser application in the UK is approximately 100 kilograms per hectare, with the highest experimental amounts showing the sharpest declines in biodiversity. Interestingly, plots treated with fertilisers excluding nitrogen retained a higher diversity of flowers and pollinators.
The study also measured productivity by weighing hay yields, finding a trade-off between agricultural output and biodiversity. Farmers face a challenging balance: reducing fertiliser use to protect pollinators decreases yields, but it brings environmental benefits such as improved soil health, better air quality, and resilience to climate events.
With 97% of the UK’s wildflower meadows lost since the 1930s, experts stress the urgency of adopting biodiversity-friendly practices. Financial incentives may encourage farmers to prioritize sustainability while mitigating economic losses. Prof Francis Ratnieks emphasized the study’s relevance: “This research offers valuable insights into managing agricultural landscapes to support pollinators, which are vital to ecosystems and food security.”
This century-spanning study serves as a critical reminder of the consequences of intensive farming. By rethinking fertiliser usage, policymakers and farmers can take significant steps toward preserving biodiversity and ensuring ecological balance.
