A study spanning more than 150 years found that fertilizer use has halved pollinating insects and reduced meadow wildflowers fivefold. A team from the University of Sussex and Rothamsted Research based the analysis on British data, though the trends are visible worldwide. The researchers studied the effects of heavy applications of nitrogen, potassium, and phosphorus fertilizers on agricultural pastures, focusing on damage to the Park Grass meadow plots in Hertfordshire. That site has hosted ecological observations and experiments since 1856.
The team, writing in the journal npj Biodiversity, found bees were hit hardest. In unfertilized areas, bee populations were nine times higher than in heavily fertilized meadows. Lead author Dr. Nicholas Balfour said, “As the amount of fertilizer increases, the number of pollinators decreases; this direct relationship has, to our knowledge, never been demonstrated before.” The losses happen because fertilizers favor fast-growing forage grasses that crowd out wildflowers, shrinking the meadow’s palette. That loss of floral color matters: a wider range of flower colors supports a wider range of pollinators, and insects often prefer certain colors, as reported by The Guardian.
Britain’s average fertilizer application on pastures is about 100 kg per hectare. The experiment’s highest treatment was 144 kg per hectare, which coincided with the steepest pollinator losses — declines of 50 percent or more. The effect was strongest with nitrogen fertilizers, which are used most widely. Plots treated with fertilizer mixes that excluded nitrogen retained relatively high numbers of pollinators and wildflowers. The study estimates only 1–2 percent of UK pastures now provide high-quality habitat for many species. Since the 1930s, Britain has lost 97 percent of its wildflower meadows, and the trend is worsening because of heavy fertilizer use.
The study highlights a paradox for farmers: boosting wildflower and pollinator diversity often means making the land less fertile, which usually reduces yields. “While reduced yields are generally not seen as a good thing, lower-intensity pasture production can unlock many benefits of multifunctional landscapes,” Dr. Balfour said. Those benefits include bigger pollinator populations, healthier soils and cleaner air, and greater resilience to extreme weather.
