How Intensive Farming Practices Harm Pollinators: The Hidden Costs of Fertilizer
High fertilizer use is often heralded as a solution for increasing agricultural yields, but a groundbreaking study reveals it comes at a significant environmental cost—halving pollinator populations and reducing floral biodiversity. Conducted over nearly 150 years at Rothamsted Research’s Park Grass experiment, this research provides an unprecedented look into how fertilizers disrupt the delicate balance of grassland ecosystems.
Understanding the Role of Fertilizers in Grassland Ecosystems
The study, led by the University of Sussex and Rothamsted Research, found that increasing the use of nitrogen, phosphorus, and potassium fertilizers on grasslands reduced the number of flowers by a staggering fivefold and halved pollinator numbers. These declines were most pronounced with nitrogen-based fertilizers, the most widely used type. In chemical-free plots, researchers observed over nine times more bees compared to those treated with high levels of fertilizers, emphasizing the detrimental impact of such agricultural practices on biodiversity.
Dr. Nicholas Balfour, lead researcher from Sussex University, explained, “As you increase fertilizers, pollinator numbers decrease—that’s the direct link that’s never been shown before.” Fertilizers promote the dominance of fast-growing grasses, which crowd out flowers and reduce habitat for pollinators, leading to cascading effects on the food chain.
The Impact of Fertilizers on Pollinator Populations
The findings have significant implications for farming and conservation. While the average fertilizer use in the UK is 100kg per hectare, even this level was shown to result in 42% fewer pollinators and a drastic reduction in flowers. The trade-off between maximizing grassland yields and supporting biodiversity is evident. More fertile lands yield more hay but at the expense of vital pollinators, such as bees, butterflies, and hoverflies, which are essential for ecosystem health and food production.
With 97% of the UK’s wildflower meadows lost since the 1930s, and only 1%-2% of grasslands now classified as species-rich, these findings underscore the urgent need for sustainable farming practices. The study advocates for financial incentives to promote biodiversity-friendly methods, such as reduced fertilizer use, which could improve soil health, air quality, and resilience to climate extremes, alongside benefiting pollinators.
Prof. Francis Ratnieks, co-author and entomologist at Sussex University, stated, “Considering the current focus on fertilizer use and the substantial declines in pollinator numbers, this study couldn’t come at a better time.” He highlighted the importance of educating landowners on creating multifunctional landscapes that balance productivity with environmental stewardship.
How Reduced Yields Can Benefit Ecosystems and Climate Resilience
Dr. Philip Donkersley from Lancaster University, who was not involved in the study, praised its long-term approach. Unlike most ecological studies that span only a few years, the Rothamsted experiment spans nearly 150 years, offering unparalleled insights into the cumulative effects of fertilizers on ecosystems.
While reduced yields might not initially seem advantageous, the study argues that less-intensive grassland management could deliver long-term benefits for biodiversity, climate resilience, and ecosystem services. These findings challenge traditional farming paradigms and call for a shift toward practices that prioritize ecological balance over short-term gains.
Learn more about vital pollinator ecosystems and how to make a difference in your community by reading our other bee blog posts.