Tag: sustainability

The Interconnected Challenges of Nitrogen and Protein in the Netherlands – A broader Vision is needed for Spacial Planning including the Opportunities for Change!

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The Netherlands faces a confluence of two critical and interconnected challenges: the nitrogen crisis and the protein transition.These issues are symptomatic of a broader societal debate about land use, sustainability, and the future of agriculture. Contentious aspects include balancing the expansion of urban areas with preserving natural habitats, managing agricultural emissions while ensuring food security, and addressing the economic impacts of transitioning to sustainable practices. As I argued in a recent interview, the question underpinning these challenges is simple yet profound: what do we want our country to be?

Part 1: The Nitrogen Crisis – A Spatial Planning Issue

At the heart of the nitrogen problem lies the excessive emission of ammonia (NH₃), primarily from livestock farming. This has led to stringent government policies that have strained farmers, businesses, and broader society. As a physicist and modeler by training, I see significant flaws in how nitrogen models are used to guide policy. These models, while valuable as tools for monitoring and scenario analysis, have often been applied in a reductive and rigid manner.

One of the key failures is the lack of integration between disciplines. Decisions about nitrogen are deeply tied to spatial planning—an area where the Netherlands once excelled. My father, as part of the team that designed and developed Southern Flevoland, worked in multidisciplinary teams of engineers, urban planners, and sociologists. Their approach balanced long-term visions with immediate practical decisions. Today, such integrated thinking seems lost, in part due to shifts in governance that prioritize sectoral policies over interdisciplinary collaboration. Changes such as increased bureaucratic fragmentation and a reliance on short-term managerial goals have replaced the long-term, multidisciplinary approaches that once defined Dutch spatial planning. We rely on fragmented decision-making processes where jurists and managers dominate, often paralyzing progress.

The nitrogen debate exemplifies this. Policies have been reduced to calculations of critical deposition values (critical loads), which in turn narrow the focus to ammonia emissions. While these are valid considerations, they fail to address the larger question: how should we organize our land to balance agriculture, nature, and urban development?

Part 2: The Protein Transition – An Opportunity for Change

Parallel to the nitrogen crisis is the ongoing protein transition—the shift from animal-based to plant-based proteins. This movement is not just about sustainability but also about recalibrating our agricultural systems. Livestock farming consumes vast resources, from land to feed crops, while generating significant environmental externalities, including ammonia emissions.

The transition to plant-based proteins presents an opportunity to mitigate these challenges. For example, reducing livestock numbers could lower nitrogen emissions, freeing up land for other uses or more sustainable farming practices. Yet, this transition is not without hurdles. Plant-based protein products, such as meat alternatives, are often priced higher than their animal-based counterparts due to inefficiencies in scaling production, higher costs of raw materials, and underdeveloped supply chains compared to the well-established meat industry. These barriers must be addressed to make sustainable diets more accessible.

One potential solution is to implement policies that incentivize sustainable practices while disincentivizing resource-intensive ones. This could include taxes on meat and dairy products or subsidies for plant-based alternatives. However, such measures must be balanced to ensure they are socially equitable and do not disproportionately burden lower-income households.

Part 3: The Need for a Broader Vision

What ties these issues together is the need for a cohesive national vision for land use. The Netherlands is a small, densely populated country. Balancing competing demands for housing, agriculture, industry, and nature conservation requires a return to integrated spatial planning. The nitrogen crisis and protein transition are not isolated problems; they are symptoms of a larger failure to define and pursue a shared vision for the future.

Modern tools, such as scenario modeling and gamification, can support this process. For example, in Germany, scenario modeling was used to assess land use changes for renewable energy projects, enabling policymakers to balance ecological preservation with energy goals. Similarly, gamification tools have been employed in urban planning to simulate the impacts of zoning changes, fostering more informed community discussions. Imagine using interactive models to explore different visions for the Netherlands—from rewilding large swathes of land to creating high-tech agricultural hubs. These tools could help policymakers and citizens visualize trade-offs and make informed decisions.

Part 4: Moving Forward – A Holistic Approach

To address the nitrogen crisis and accelerate the protein transition, we must adopt a holistic approach. This means:

  1. Reintegrating Disciplines: Bring together scientists, policymakers, and practitioners to craft solutions that account for ecological, economic, and social dimensions.
  2. Redefining Metrics: Move beyond critical loads and ammonia emission levels to broader indicators of sustainability, including biodiversity, soil health, and societal well-being.
  3. Engaging Citizens: Foster public dialogue about land use and sustainability to build consensus around difficult trade-offs. Start a national discussion about the future of the Netherlands. What kind of country do we want to build?
  4. Leveraging Technology: Use scenario modeling and gamification to make complex policy decisions more transparent and participatory.

The nitrogen crisis and protein transition challenge us to rethink how we live, farm, and consume. Addressing these issues requires adopting a holistic approach: reintegrating disciplines, redefining sustainability metrics, engaging citizens in public dialogue, and leveraging tools like scenario modeling to guide decision-making effectively. By reconnecting these debates to the larger question of what kind of country we want to be, the Netherlands can turn these challenges into opportunities for innovation and progress.

Understanding Dry Deposition: Mechanisms, Modeling Challenges, and the Complexities of Ammonia’s Interaction with Different Surfaces in Environmental Systems

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Dry Deposition – What is it?

When we think of wet deposition, it’s easy to imagine ammonia (or NOx) dissolving in raindrops and falling to the ground in a form that enriches the soil. But what about dry deposition? Molecules like ammonia can’t just “fall” to the ground, nor do they rise on their own. In the previous chapter, we discussed how turbulence in the mixed layer allows for dispersion in all directions. So, if molecules can’t fall, what mechanisms bring ammonia to the ground? The scientific literature is sparse, so we refer to a source called De Vliegende Geest.

The dry deposition flux is determined by the concentration in or on the leaf (in the water layer) and the level of turbulence in the atmosphere. Higher turbulence leads to more transport from the air to the surface. Turbulence itself depends on wind speed, sunlight, and surface roughness. Greater wind speed and roughness increase deposition. Surface roughness varies by terrain: rough surfaces like forests and cities have higher roughness, whereas water has the lowest. Wet surfaces, such as after rainfall or in high humidity, tend to absorb more ammonia.

While this description covers general concepts, it doesn’t fully explain the physical mechanisms that occur just above the ground, allowing the exchange of ammonia gas with the surface. There’s less scientific literature on why this exchange happens. However, we can hypothesize some physical-chemical processes that make dry deposition plausible:

  • Fine particles can fall to the ground, particularly larger ones. Ammonium salts, like ammonium sulfate, can deposit on the ground.
  • The cuticle of plants, a waxy layer on the epidermis, can attract ammonia from the air when wet.
  • Ammonia can be absorbed by plants through stomata under certain conditions, known as the “compensation point.”
  • Moist surfaces like wet clay, sand, or water can absorb ammonia from the air. Depending on acidity or ammonium concentration, a wet surface can also emit ammonia back into the air.

This list isn’t exhaustive, but it shows that dry deposition is a real, complex phenomenon involving many interactions, like the exchange between gaseous ammonia and ammonia dissolved in aerosols. Additionally, ammonia can condense on fine dust particles or adsorb onto them.

The Basis of Dry Deposition Modeling

Dry deposition models rely on accurate concentration measurements above the surface, but ammonia concentrations are challenging to measure via satellites. To overcome this, the Dutch National Institute for Public Health and the Environment (RIVM) uses models (such as Aerius) to predict concentrations above different surfaces.

There are significant discrepancies between predicted and measured ammonia concentrations, which the RIVM sometimes compensates for by inventing emission sources (like ammonia from the sea). Emission sources, especially in agriculture, are not precisely known, and the deposition speed per land type isn’t well understood.

Mathematically, the simplest model assumes a linear relationship between deposition and the concentration difference between the air and the surface. This model uses a fixed deposition speed and can be written as:

Deposition = deposition speed * (air concentration)

More advanced models consider the variability of deposition speed over time and space, incorporating factors like seasons, weather, and surface roughness. These models use an exchange velocity, reflecting that under certain conditions, emissions can occur instead of deposition.

The Resistance Model: Ra + Rb + Rc

The deposition of gases like ammonia is influenced by various resistances that affect the movement of the gas from the atmosphere to the ground. The total resistance is the sum of three components:

  1. Aerodynamic Resistance (Ra): This depends on wind speed and surface roughness. Higher winds and rougher surfaces lower the resistance, increasing the efficiency of air transport to the surface.
  2. Laminar Boundary Layer Resistance (Rb): This occurs in the thin layer of air just above the ground, where air moves in a less turbulent, layered flow. It depends on surface and gas properties like temperature and turbulence.
  3. Surface Resistance (Rc): This reflects how easily the surface absorbs the gas. For ammonia, factors like surface moisture and acidity play a role. Rc is highly dependent on land type, vegetation, and other surface characteristics.

The DEPAC Model for Dry Deposition

Dry deposition is typically calculated using models like DEPAC, which simulate how substances from the air settle on the ground. DEPAC is integrated into the OPS model, widely used to create large-scale deposition maps in the Netherlands. The model incorporates factors like vegetation, surface roughness, and weather to estimate deposition rates.

Recent improvements in the DEPAC model account for ammonia in vegetation and soil, meaning that ammonia can be absorbed and emitted depending on environmental conditions. The model is quite complex, but it offers valuable insights into how different surfaces interact with airborne ammonia.

Conclusion

Dry deposition of ammonia is influenced by many factors, including surface characteristics, turbulence, and atmospheric conditions. Although models like DEPAC provide a way to estimate deposition rates, there is a significant need for more field data and validation to ensure accurate predictions, especially for critical ecosystems like grasslands, forests, and urban areas.