The Nitrogen debate - Need for a new nitrogen policy
Benefits and threats of nitrogen
Nitrogen (N) is the most important nutrient for plant growth. It is an element that abounds in the air in the form of the dinitrogen gas (78 percent of the air consists of it), but this form cannot be used by plants. At the beginning of the 20th century, however, a discovery was made that changed the world: the conversion or fixation of dinitrogen (N2), in combination with hydrogen (H), into the gas ammonia (NH3). Since then, nitrogen has been applied as a fertilizer to land, causing a tremendous increase in crop yield and related human population. The downside of this N2 fixation, causing an enhanced rate of N fertilizer and N manure application, is, however, the loss of N to air and water in various forms. These losses include NH3 and nitrous oxide (N2O) to air and leaching of nitrate (NO3) to ground water and surface water. In addition, the increase in traffic and industry enhanced the conversion of N2, in combination with oxygen (O2) to nitrogen oxides (NO and NO2).
These N losses lead to impacts on human health, climate, and ecosystems. Human health impacts are due to: (i) elevated NO2 concentrations, (ii) NOx induced elevated ozone concentrations, (iii) NH3 and NOx induced formation of particulate matter, and (iv) pollution of groundwater and drinking water due to NO3-leaching. Global warming is mainly due to emissions of N2O, being a greenhouse gas. Impacts of terrestrial and aquatic ecosystems are a decrease of floristic and faunal species diversity due to N enrichment (eutrophication) and (soil) acidification. In terrestrial ecosystems, this is mainly due to atmospheric deposition of NH3 and NOx.
The cause of the nitrogen crisis
Excess nitrogen deposition on areas has been problematic since 1980, when the Netherlands suffered from ‘acid rain’. Apart from sulfur dioxide (SO2), it was also made up of nitrogen oxides (NOx) and ammonia (NH3). Since then, the Dutch government has cut nitrogen emissions. Emissions of nitrogen oxides and ammonia have been halved since 1990. And yet nitrogen deposition is still higher than the so-called critical load on about three quarters of Dutch land devoted to nature. Moreover, emissions of ammonia have hardly decreased since 2010. The program for tackling nitrogen (PAS), which the government introduced in 2015 aimed at simultaneously reducing N emissions, and thus deposition on nature, while offering options for new economic activities that involve N emissions. Permit to build new barns or roads were given on the premise that measures reducing emissions, such as low-emission housing for livestock or low-emission manure application techniques would be applied at the same time. This premise was not fulfilled and the Council of State thus concluded in May 29, 2019, that the PAS should no longer be used as a basis for authorizing nitrogen-emitting activities in anticipation of the positive effects of PAS measures. This caused the so-called nitrogen crisis
Drawbacks of the current nitrogen policy
In current nitrogen policy, licensing is based on a permissible increase in deposition on a nearby Natura 2000-area and an atmospheric transport model is used to calculate this increase. That policy is complex and disputable for several reasons. First of all, an emission source contributes more to nearby deposition, but its deposition is nevertheless transported over hundreds of kilometers (NH3) to thousands of kilometers (NOx). The emission of both substances, therefore, contribute to a high nitrogen background deposition across the Netherlands and it is important to reduce that background deposition. Second, there are uncertainties in both the current and critical N deposition, which increase going from national to provincial to local level. Uncertainties are not a reason for doing nothing, but the high uncertainties in a local-scale deposition do raise questions when it comes to the local scale focus in licensing. Finally, there is harmonization between national and provincial policy. At the national level, the so-called 'National Emission Ceiling has to be achieved for both NOx and NH3. These ceilings are much higher than the N emission ceiling that would be needed to ensure N deposition that approaches the critical loads for all Natura 2000-areas. In fact, with the current import of N from other countries it is not even possible to achieve the critical load for the most sensitive Natura 2000-areas. As a result, there is no consistency between a very flexible national emission policy and a very strict provincial deposition policy.
Building blocks for a new nitrogen policy
In view of the drawbacks of the current nitrogen policy, I suggest the following building blocks for a new nitrogen policy;
- Reconsider the focus on local deposition policy when granting a permit: focus on generic emission policy.
- Determine a realistic national emission limit value: a national emission ceiling that can ultimately be achieved, which protects most of the Natura 2000 area (all is not possible). To protect ca 70 percent of the Natura 2000-areas, implies at least a 50 percent emission reduction.
- Determine a time frame in which the emission reduction must be realized. In connection with the climate agreement, the years 2030 and 2050s could be leading.
- Divide the national emission ceiling for ammonia between provinces.
- Introduce a "cap and trade" system to reduce NH3 and NOx emissions. Companies can then decide for themselves what is most cost-effective: investing in cleaner technology or buying emission rights.
- As an only local policy: Do not give permission for activities that result in an undue increase in the N-deposition on a Natura 2000-area, focusing on a range of 0.5 -1 km near that area.
This approach will be beneficial for nature, given related policies to support especially farmers for their investments.
Wim de Vries
Professor Integrated Nitrogen Impact analyses at Wageningen University