Facts on Sustainable Nutrient Management *UN Environmental Program*

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What do we mean by Nutrients & What is the Problem?

Nutrients are natural chemical substances that are essential to sustaining life - needed by plants,?animals and people.

Macronutrients are those that are needed by the plants in larger quantities and include: nitrogen, phosphorus, potassium, sulphur, magnesium, and calcium.

• Micronutrients , including minerals such as boron, chlorine, copper, iron, manganese, zinc and nickel are still vital for healthy growth but needed in smaller quantities.
• As humans we can only access these nutrients through the food we eat. To make sure that the food we eat is sufficiently nutritious, it is important to ensure crops receive the appropriate nutrients supply while they are growing.
• Discussions on nutrient management tend to focus on Nitrogen and Phosphorus - around half of the world’s food security is dependent on these two nutrients.
• A recent assessment of the earth’s planetary boundaries shows that these important nutrient cycles have been disrupted by human activities, such as the misuse of fertilizers, resulting in increased volumes of runoff and wastewater. This puts the earth’s systems at high risk of fundamental change.
• Wastewater is the major carrier of nutrients to freshwater and marine ecosystems. Nutrients are present in urban and industrial wastewater, agriculture and aquiculture effluents, run-off and urban storm water.
• An imbalance in nutrient management occurs from both a lack and an excess of these nutrients. Nutrient deficiency is called nutrient mining . It occurs where there is insufficient access to fertilizers. The plant nutrients removed by growth and harvesting are not replenished, resulting in decreased soil health, lower yields or even failed crops. This can undermine food security.
• Pollution from excess nutrients through overuse or misuse of fertilizers, as well as insufficient municipal and industrial wastewater management is a key driver of biodiversity loss , undermining ecosystem function and ecosystem services in soils, lakes, rivers, streams and coastal waters.
• Developing strategies to manage nutrients sustainably is critical to tackling each aspect of the triple planetary crisis.

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In Chemicals & pollution action

How does nutrient management affect the three aspects of the triple planetary crisis?

The climate crisis

• Changes to weather and rainfall patterns are making it more difficult to predict plant nutrient requirements.
• Changes in temperature, soil pH and carbon dioxide concentrations affect the availability of nutrients and how they are used by the plant, thereby impacting the timing and the amount of fertilizers needed to achieve sufficient nutritional value.
• The production and use of synthetic nitrogen fertilizer alone is estimated to account for 5% of greenhouse gas emissions with around two thirds of the emissions taking place after they are applied.
• Nitrous oxide (N2O) is one of the primary greenhouse gasses. It is about 300x more potent than carbon dioxide and can exist in the atmosphere for around 100 years. The largest share of N2O comes from the application of nitrogen fertilizers to agricultural lands.
• A sustainable nutrient management strategy that includes the use of organic fertilizers and the recovery of nutrients from wastewater streams could reduce demands on synthetic fertilizers, reducing greenhouse gas emissions from the fertilizer production, transport and in its deployment on crops. It could also help increase the potential for carbon sequestration in agricultural soils.
• Improving the efficiency and effectiveness of fertilizer use, thereby also reducing its demand, can help reduce N2O emissions.
• Circularity of nutrients, recovering and recycling them from different waste streams, such as wastewater, food waste, industrial discharges and food production processes, can help reduce greenhouse gas emissions .
• Nutrient recovery from waste and wastewater streams can increase access to local sources of fertilizers , thereby reducing the need to transport and ship fertilizers, resulting in cost savings and reduced emissions.

The crisis of nature and biodiversity loss

• Nitrogen and phosphorus can be the factor that limits plant growth. But an excess of these nutrients in aquatic ecosystems can trigger algal blooms which consume available oxygen and block light. This results in eutrophication – low oxygen conditions that are unsuitable for most species to survive. In the worst cases these areas become dead zones impacting local fisheries, local livelihoods, tourism, and causing health problems.
• Excess nitrogen can also affect the pH of soil and water by making it more acidic. This can have negative impacts on terrestrial, freshwater and marine biodiversity.
• Healthy nearshore coral reefs thrive as low nutrient ecosystems. They are particularly sensitive to additional nutrient inputs , which can disrupt the ecosystem and trigger disease. Reducing nutrient pollution through improved management and increased recovery can help coral reefs cope with other pressures such as climate change induced warming.
• The Global Biodiversity Framework (GBF) Target 7 calls for excess nutrients lost to the environment to be cut by half by 2030 , as a contribution to reducing pollution levels to a point where they are no longer harmful to biodiversity. Reducing pollution as a key pressure will also be a pre-requisite for the successful restoration of degraded ecosystems .

The pollution crisis

• Excess nutrients pollute air, land and water , negatively impacting human and environmental health with significant economic and social costs.
• The overall environmental costs of nutrient pollution in Europe has been estimated at?€70–€320 billion per year . Climate change impacts such as warming of aquatic systems is anticipated to amplify the impact of pollution, exacerbating their impacts on biodiversity and ecosystem function.
• In the air, N2O and NH3 contribute to greenhouse gas emissions, undermine air quality and negatively impact human health.
• In water, excess nutrients cause eutrophication reducing the quality of groundwater, inland water and coastal environments. Lakes and coastal areas are particularly susceptible to eutrophication.
• On land, disruptions to the nutrient balance impact soil health which can have negative consequences on our food systems and nutrition.
• In addition to improving agricultural practices, progressing towards SDG target 6.2 to increase access to sanitation and target 6.3 to reduce the proportion of wastewater being released untreated, will contribute significantly to reducing nutrient pollution from wastewater and increase opportunities for nutrient recovery and reuse.
• Tackling nutrient-related pollution problems has been identified as a key to addressing the other two planetary crises.

What can be done to strengthen sustainable nutrient management?

Too often the problems of nutrient imbalance are invisible on the political agenda or considered a low priority against other competing demands. The economic, regulatory and policy incentives for sustainable nutrient management have been weak and inconsistent . There are severe risks to human health, food security, environmental health and the economy if this issue is not adequately addressed, for example by:

• Prioritizing policy and regulatory coherence. The nutrient issue is central in many policy domains: health, food systems, water, waste management, energy, urban planning, economics, biodiversity, and environment.? Sustainable nutrient management requires a holistic, circular multi-sector and transdisciplinary systems-wide approach that connects across sectors.
• Increasing capacity to apply best farming practices. As the basis for healthy food production, healthy soils supply the essential root support, water, nutrients, and oxygen that our food-producing plants need to grow. Increasing the capacity of farmers to actively manage soil health - such as through the adoption of best practices in fertilizer application, integration of cover crops, and development of policies that incentivize water conservation practices – can produce multiple social and environmental benefits.
• Tackling the challenge of circularity. Technologies exist to recover nutrients from wastewater streams , processes that can also recover energy and reduce discharge. It is important to consider all the options for recovery of nutrients, energy to maximise synergies, develop the scale to stimulate new markets and avoid discharge and clean-up costs through reduced pollution.
• Innovate not only technologies but also working processes . There are technologies for recovering phosphorus, nitrogen, potassium and micro-nutrients at different stages of development from investigation through to commercial operations.

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50% is the amount by which nutrient losses can be reduced from agriculture by 2030 without compromising food security using existing technologies and best practices.

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