Fertilizer is commonly used to help boost crop production, but a new study indicates that its use could actually reduce “abundance and species richness” of flowering plants. This research was published Monday in the Nature Biodiversity journal.
“Both flower abundance (5.18 times) and species richness (8.46 times) were severalfold greater in the two untreated plots than in the two receiving the greatest amount of fertilizer,” said the study authors, who conducted their research at The Park Grass Experiment in Rothamsted, southeast England. Established in 1856, it is the world’s longest-running ecological experiment.
The research team also revealed that the data showed “a large and significant negative effect,” on pollinators. In plots that were not treated with fertilizer, pollinator abundance was 95% greater abundance and richness was 84% greater compared to those that received a high level of fertilizers.
For example, Bees – a key pollinator group – were more numerous in untreated plots. While all pollinators, including bees, were present in untreated plots and those with low levels of fertilizers, plots that received high levels of fertilizers were dominated by flies and beetles.
“Our findings are a salutary reminder of the challenge in reconciling conflicting aims in farmland management and strongly suggest that financial incentives are necessary to offset yield reductions to improve biodiversity outcomes in agricultural grasslands,” said the study.
Its authors noted that nearly a quarter of the Earth’s land area is agricultural grassland that contributes to the livelihoods of over 800 million people. Although fertilization of this land has helped increase global food production, the researchers wanted to highlight risks associated with the process, including environmental degradation and adverse effects on human health and welfare.
According to the U.S. Environmental Protection Agency, “most fertilizers that are commonly used in agriculture contain the three basic plant nutrients: nitrogen, phosphorus, and potassium.”
In the U.S., fertilizer consumption grew rapidly throughout the 1960s and 1970s, per the U.S. Department of Agriculture, and reached a peak of 23.7 million nutrient short tons (1 short ton is equal to 2,000 pounds) in 1981. In 2008, farmers reduced their use of fertilizers in response to record high prices and that contributed to a price decline that persisted through 2010. Although prices did recover somewhat, as of this year they are trending downward.
“This is a critical moment for land use policy globally, with many countries (e.g. the UK and the European Union) currently undertaking significant green reforms of their agricultural policies,” the study authors said.