Fertilizer's Water Pollution: Understanding The Environmental Impact

Fertilizers are essential for crop production, but they can also be a significant source of water pollution. Excessive use of fertilizers can lead to nutrient runoff, which impacts water quality and aquatic ecosystems. When too much fertilizer is applied, the excess nutrients, mainly nitrogen and phosphorus, can enter water bodies through runoff and soil erosion, causing a range of environmental and health issues. This process, known as eutrophication, leads to the acceleration of algae growth, depleting oxygen levels in the water and creating dead zones where aquatic life cannot survive. The impact of fertilizer pollution extends beyond the immediate ecosystem, as it can also contaminate drinking water sources and affect human health, with high nitrate levels posing risks to infants, pregnant women, and those with gastric issues. Addressing this issue requires proper nutrient management techniques, conservation practices, and collaboration between farmers, stakeholders, and organizations to reduce nutrient loss and protect water quality.

Nitrogen and phosphorus runoff

Nitrogen and phosphorus are nutrients that are natural parts of aquatic ecosystems. Nitrogen is also the most abundant element in the air we breathe. Nitrogen and phosphorus support the growth of algae and aquatic plants, which provide food and habitat for fish, shellfish, and smaller organisms that live in water.

However, when too much nitrogen and phosphorus enter the environment, usually from a wide range of human activities, the air and water can become polluted. Nitrogen and phosphorus runoff from agricultural fields are some of the largest sources of pollution to coastal “dead zones” across the United States. For example, in Florida, toxic blue-green algal blooms have been triggered by releases of phosphorus-laden waters from Lake Okeechobee.

Excess nitrogen in the atmosphere can produce pollutants such as ammonia and ozone, which can impair our ability to breathe, limit visibility, and alter plant growth. When excess nitrogen comes back to earth from the atmosphere, it can harm the health of forests, soils, and waterways. Excess nitrogen can be lost from farm fields in the form of gaseous, nitrogen-based compounds, like ammonia and nitrogen oxides.

Excess nitrogen and phosphorus can be washed from farm fields and into waterways during rain and snowmelt, and they can also leach through the soil and into groundwater over time. This process is known as eutrophication, which causes algae to grow faster than ecosystems can handle. Algal blooms produce a foul odour along waterways, decrease dissolved oxygen, threaten insect and fish communities, and can even produce toxins that are harmful to mammals and humans.

To reduce nitrogen and phosphorus runoff, farmers can improve nutrient management practices by applying nutrients (fertilizer and manure) in the right amount, at the right time of year, with the right method, and with the right placement.

Eutrophication and hypoxia

Eutrophication is a type of pollution caused when excess nutrients, primarily nitrogen and phosphorus, enter a water body. This overload of nutrients causes algae to grow uncontrollably, depleting the water of oxygen as they die. This phenomenon, known as hypoxia, results in oxygen levels becoming so low that the water can no longer support aquatic life. Eutrophication can be caused by the overuse of fertilizers, which can run off into streams and lakes, causing toxic algal blooms that are harmful to aquatic life and even people and their pets.

Excess nitrogen and phosphorus from fertilizers can be washed from farm fields into waterways during rain and snow melt and can also leach through the soil into groundwater over time. Drainage water from farms can carry soluble forms of nitrogen and phosphorus, and strategies are needed to reduce nutrient loads while maintaining adequate drainage for crop production. This is especially important for fields that border water bodies, where buffers of trees, shrubs, and grasses can be planted to help prevent nutrient loss by absorbing or filtering out nutrients before they reach a water body.

Eutrophication has emerged as one of the leading causes of water quality impairment, with hypoxia (or oxygen depletion) and harmful algal blooms being two of its most acute symptoms. These algal blooms can cause fish kills, human illness through shellfish poisoning, and the death of marine mammals and shorebirds. Hypoxia has escalated dramatically over the past 50 years, increasing from about 10 documented cases in 1960 to at least 169 in 2007.

Aquaculture (fish farming) is another growing source of nutrient pollution that can contribute to eutrophication and hypoxia. These farms generate concentrated amounts of nitrogen and phosphorus from excrement, uneaten food, and other organic waste, which can have severe impacts on aquatic ecosystems if improperly managed.

Algal blooms

HABs can have severe impacts on water quality, food resources, and habitats. They can also decrease the oxygen that fish and other aquatic life need to survive, leading to a condition known as hypoxia. In hypoxic conditions, aquatic life can become stressed, and if oxygen levels deplete further, no aquatic life can survive. This leads to the creation of "dead zones", where no aquatic life can be supported. These dead zones can have massive impacts on local economies, particularly the fishing industry.

Excess nutrients can enter waterways through fertilizer runoff from agricultural fields, lawns, and residential areas. Fertilizer use in agriculture is a significant source of nutrient pollution to water, with nitrogen and phosphorus runoff from farms being some of the largest contributors to coastal dead zones. Residential areas can also contribute to nutrient pollution through the use of fertilizers, yard waste, and certain soaps and detergents that contain nitrogen and phosphorus.

The impact of algal blooms can be seen in the decrease in water clarity and visibility. Repeated blooms can turn lakes green, with low oxygen levels that are harmful to aquatic life and humans. In severe cases, algal blooms can produce toxins that are dangerous to humans, causing asthma-like symptoms, severe vomiting, diarrhea, or irritated skin and eyes. These algal toxins have also been linked to the deaths of various animals, including dogs, birds, and fish.

Controlling algal blooms requires a reduction in nutrient runoff, which can be achieved through decreased fertilizer use, improved timing and methods of application, and the adoption of conservation practices such as drainage system modifications and the use of cover crops.

Watershed efforts

• Adopting Nutrient Management Techniques: Farmers can improve nutrient management practices by applying the right amount of fertilizer at the right time of year, with the right method, and in the right place. This can significantly reduce the amount of fertilizer that reaches water bodies.
• Conservation Drainage Practices: Implementing subsurface tile drainage can help manage water movement through soils, particularly in the Midwest. While drainage water can carry soluble forms of nitrogen and phosphorus, conservation drainage practices aim to reduce nutrient loads while maintaining adequate drainage for crop production. This includes modifying drainage system design and operation, using woodchip bioreactors, saturated buffers, and making changes to the drainage ditch system.
• Ensuring Year-Round Ground Cover: Farmers can plant cover crops or perennial species to prevent bare ground on farm fields, reducing the risk of erosion and nutrient loss into waterways.
• Planting Field Buffers: Planting trees, shrubs, and grasses along the edges of fields, especially those bordering water bodies, can help absorb or filter out nutrients before they reach water bodies.
• Implementing Conservation Tillage: Reducing the frequency and intensity of tilling can improve soil health, reduce erosion, runoff, and soil compaction, thereby decreasing the chance of nutrients reaching waterways.
• Managing Livestock Access to Streams: Installing fences along streams, rivers, and lakes can help keep animals and their waste out of the water, reducing nutrient pollution and protecting stream banks.
• Community Education and Awareness: Educating the public about the impacts of fertilizer use and providing information on alternative practices can empower individuals to make informed decisions about their fertilizer use and support environmental initiatives.
• Water Conservation: Encouraging water conservation practices, such as shorter showers, fixing leaks, and using water-efficient appliances, can reduce the overall demand for water and help protect watersheds.
• Proper Disposal of Chemicals: Educating the public about the proper disposal of household chemicals and hazardous waste can prevent toxic substances from entering water bodies and impacting water quality.
• Alternative Landscaping: Promoting the use of hardy plants that require less water, fertilizers, and pesticides in yards and public spaces can reduce the potential for fertilizer runoff and improve watershed health.
• Soil Testing: Encouraging farmers and landowners to test their soil before applying fertilizers can help ensure that nutrients are only added when necessary, reducing the risk of over-application and subsequent runoff.

Nutrient management

Applying Fertilizers Properly

Farmers play a crucial role in nutrient management by applying fertilizers in the right amount, at the appropriate time of year, with the suitable method, and in the correct placement. This approach significantly reduces the amount of fertilizer that reaches water bodies. It is also essential to be aware of the soil's nutrient levels before applying fertilizers, as over-fertilization can lead to runoff and water pollution.

Adopting Conservation Practices

Implementing conservation drainage practices is vital to managing water movement through soils. This includes techniques such as subsurface tile drainage, modifying drainage system designs, using woodchip bioreactors, saturated buffers, and making adjustments to the drainage ditch system. These strategies aim to balance reducing nutrient loads while maintaining adequate drainage for crop production.

Planting Field Buffers

Planting trees, shrubs, and grasses along the edges of fields, especially those bordering water bodies, is an effective way to prevent nutrient loss. These buffers act as natural filters, absorbing and trapping excess nutrients before they reach nearby water bodies.

Reducing Tillage Intensity and Frequency

By decreasing the frequency and intensity of tilling, farmers can improve soil health and reduce erosion, runoff, and soil compaction. This, in turn, minimizes the chances of nutrients, particularly nitrogen and phosphorus, from reaching waterways through runoff.

Managing Livestock Access to Waterways

Keeping livestock and their waste away from streams, rivers, and lakes is essential. Farmers can achieve this by installing fences along these water bodies to block animal access. This practice helps restore stream banks, protects them from erosion, and prevents excess nutrients, especially nitrogen and phosphorus, from entering the water.

Ensuring Year-Round Ground Cover

Farmers can plant cover crops or perennial species to prevent bare ground on farm fields. This practice reduces the vulnerability of the soil and nutrients to erosion, especially during periods of heavy rainfall or irrigation.

Engaging in Watershed Efforts and Collaboration

Collaboration among farmers, state governments, conservation groups, educational institutions, and community organizations is vital to reducing nutrient pollution. Farmers can take on leadership roles in these collective efforts, implementing and promoting best practices for nutrient management across agricultural communities.

By adopting these nutrient management techniques, farmers can play a crucial role in minimizing fertilizer pollution in water bodies, protecting aquatic ecosystems, and ensuring the sustainable use of natural resources.

Frequently asked questions