The current nitrogen crisis in the Netherlands and Flanders illustrates how inefficient nutrient management can lead to both serious ecological damage and political and societal upheaval. To stop ecosystem degradation and limit further damage costs, the European Union (EU) needs an integrated Nutrients Directive that regulates the combined agricultural use of nitrogen and phosphorus, urges a new comment in Nature reviews Earth and environment. This directive must go beyond the current regulations, which are insufficient, by taking into account nutritional balance sheets and taking account of regional differences.
The long-term use of fertilizers in industrialized agriculture and the resulting build-up of nitrogen and phosphorus in the environment contribute to the widespread loss of biodiversity and disruption of ecosystems across Europe.
When it comes to plants, the species most at risk are those that are adapted to low nutrient levels or poorly buffered against acidification. In Europe, ecologically valuable grasslands, moors, peat bogs, forests, arctic and mountain ecosystems are particularly vulnerable. The animal kingdom is not safe either. Nitrogen and phosphorus reach streams and lakes as agricultural runoff. This nutrient pollution can then cause eutrophication, resulting in algal blooms that cloud the water, deprive plant life of sunlight, and deplete available oxygen in the water, smothering fish. This has implications for predators of fish and other species linked together by the complex food web of each ecosystem.
“Past and present EU policies have proven inadequate for the management of nutrients like nitrogen and phosphorus,” says Martin Wassen, professor of environmental science at Utrecht University and lead author of the publication. For example, the uninterrupted use of fertilizers means that phosphorus builds up in soils in forms which are not directly available to crops and which are harmful to the environment. Despite this, farmers continue to fertilize every year, even as exploitable phosphorus supplies become scarce and prices rise.
Current policies also often target only nitrogen, even though the ecological impacts come from the imbalance between nitrogen and phosphorus. Decreased nitrogen deposition due to EU legislation has significantly increased the phosphorus to nitrogen ratio in several grasslands in northwestern Europe. “A further reduction in nitrogen deposition without simultaneously reducing phosphorus will lead to the extinction of more grassland species than if nitrogen is not reduced at all,” Wassen explains.
The need to make food production more sustainable is recognized by the recently adopted Farm to Fork Strategy. As part of the European Green Deal, it calls for the reduction of nutrient losses to the environment by at least 50% and the use of fertilizers by at least 20% by 2030. success of the Farm to Fork strategy, international policy is urgently needed to promote sustainable nutrient application, reuse and cycling,” says co-author Jerry van Dijk, Associate Professor of Restoration Ecology and of biodiversity conservation at the University of Utrecht. “For this, we are proposing an Integrated Nutrients Directive to guide nutrient management action plans in the EU.”
An EU-wide approach is needed
To accomplish this task, according to the authors, the proposed guideline must include methods for accounting for the different ways in which nutrients behave in the environment depending on, for example, soil type, water content, nutrients or agricultural context. The guideline would also include site- and crop-specific precision farming, where fertilizer is applied as needed.
“The international dimension of the problem makes the EU the logical authority to implement the directive,” argue the authors. Nitrogen emissions diffuse into Europe through the atmosphere, and nitrogen and phosphorus cross borders through our rivers. “These nutrients are everybody’s problem. Furthermore, an EU-wide approach is also needed to avoid simply shifting nitrogen emissions from one EU country to another”.
“This directive would also contribute to existing EU environmental goals by shifting attention to pollution sources and motivating member states to work together for sustainable farming practices across Europe,” the authors conclude.