How does agriculture cause eutrophication


This excess nitrogen and phosphorus can be washed from farm fields and into waterways during rain events and when snow melts, and can also leach through the soil and into groundwater over time. High levels of nitrogen and phosphorus can cause eutrophication of water bodies.Nov 4, 2021


Is Agri-agriculture a major cause of eutrophication?

Agriculture is now considered to be a major underlying and persistent cause of eutrophication in many catchments around the world [ 30, 31, 32, 33 ].

What is the economic impact of eutrophication?

The more general costs of eutrophication related to increased water treatment for drinking, reduced value of waterfront properties, loss in amenity value and biodiversity, and adverse impacts on tourism are also very high; UK: £75–114 million [ 10 ], USA: $2.2 billion [ 11 ].

What causes eutrophication of water bodies?

High levels of nitrogen and phosphorus can cause eutrophication of water bodies. Eutrophication can lead to hypoxia (“dead zones”), causing fish kills and a decrease in aquatic life.

Do nutrient controls over agriculture reduce eutrophication in rivers?

While nutrient controls over agriculture may be justified to reduce downstream eutrophication from an accumulating nutrient pool, the ecological response of rivers to non-point P controls may be less than expected because of the limited bioavailability and accessibility of the P delivered. 3.3. Mitigating Nutrient Pressures from Farming


How does agriculture contribute to water pollution?

The most prevalent source of agricultural water pollution is soil that is washed off fields. Rain water carries soil particles (sediment) and dumps them into nearby lakes or streams. Too much sediment can cloud the water, reducing the amount of sunlight that reaches aquatic plants.

What is the main cause of eutrophication?

The most common nutrients causing eutrophication are nitrogen N and phosphorus P. The main source of nitrogen pollutants is run-off from agricultural land, whereas most phosphorus pollution comes from households and industry, including phosphorus-based detergents.

How using too much fertilizer can cause eutrophication?

Eutrophication, Hypoxia, & Dead Zones Eutrophication is a type of pollution caused when excess nutrients, primarily nitrogen and phosphorus, enter the water. The overload of nutrients cause algae to grow uncontrollably, depleting the water of oxygen as they die. Low oxygen levels in the water is known as hypoxia.

Do organic fertilizers cause eutrophication?

In other words, manure, compared to synthetic nitrogen, tends to increase eutrophication while emitting similar levels of greenhouse gases. If organic farmers relied exclusively on manure as fertilizer, eutrophication would likely worsen and pose a clear environmental threat.

How does aquaculture cause eutrophication?

In open water aquaculture systems, the excess fish feed introduces extra nitrogen and phosphorous directly into the water (Talbot & Hole 1994). Closed off inland systems contribute to eutrophication as well, as they tend to dump effluent directly into natural waterways (Talbot & Hole, 1994).

Do pesticides cause eutrophication?

pesticides application results in several effects in the ecosystem, although through direct toxicity or enriched as nutrients(eutrophication) .

Do nitrogen fertilizers cause eutrophication?

Excess nitrogen from the fertilizers can cause eutrophication in the ocean, which can lead to harmful algae blooms or hypoxia — reduced levels of oxygen that create conditions in which organisms can’t survive.

What effect do fertilizers have on rivers?

When the excess nutrients from all the fertilizer we use runs off into our waterways, they cause algae blooms sometimes big enough to make waterways impassable. When the algae die, they sink to the bottom and decompose in a process that removes oxygen from the water.

What is eutrophication in fertilizer?

Role of agriculture in eutrophication. Organic fertilizers. “Eutrophication” is the enrichment of surface waters with plant nutrients. While eutrophication occurs naturally, it is normally associated with anthropogenic sources of nutrients. The “trophic status” of lakes is the central concept in lake management.

How do fertilizers affect the environment?

Excessive use of fertilizers leads to eutrophication. Fertilizers contain substances including nitrates and phosphorus that are flooded into lakes and oceans through rains and sewage. These substances boost the excessive growth of algae in the water bodies, thereby decreasing the level of oxygen for aquatic life.

How do fertilizers cause soil pollution?

Fertilization may affect the accumulation of heavy metals in soil and plant system. Plants absorb the fertilizers through the soil, they can enter the food chain. Thus, fertilization leads to water, soil and air pollution.

How do fertilizers and pesticides cause water pollution?

Improper application of pesticides, herbicides, and fertilizers may also have an impact on storm water infiltration into groundwater. When these contaminants dissolve in storm water they find their way into the groundwater and then into surface waters, such as ponds, streams, rivers, and lakes.

What are the causes and stages of eutrophication?

Eutrophication occurs in 4 simple steps:EXCESS NUTRIENTS: First, farmers apply fertilizer to the soil. … ALGAE BLOOM: Next, the fertilizer rich in nitrate and phosphate spark the overgrowth of algae in water bodies.OXYGEN DEPLETION: When algae forms, it blocks sunlight from entering water and uses up oxygen.More items…•

What causes eutrophication quizlet?

Eutrophication occurs when there is an over excess of nutrients that is entering a body of water. Eutrophication is often the result of surface run-off from near by agricultural land by precipitation. You just studied 4 terms!

What is eutrophication also describe its causes and effects?

Harmful algal blooms, dead zones, and fish kills are the results of a process called eutrophication — which occurs when the environment becomes enriched with nutrients, increasing the amount of plant and algae growth to estuaries and coastal waters.

Can CO2 cause eutrophication?

Increasing atmospheric CO2 and eutrophication combine to acidify coastal bottom waters. Dissolution of carbon dioxide (CO2) from rising atmospheric CO2 is acidifying ocean water;but a second environmental problem, eutrophication, is having a similar effect in coastal bottomwaters.

How does conservation agriculture help the aquatic ecosystem?

Countries across the globe have agricultural agencies that provide programs for farmers to implement a variety of CAs. Increasingly there is a need to demonstrate that CAs can provide ecological improvements in aquatic ecosystems. Growing global concerns of lost habitat, biodiversity, and ecosystem services, increased eutrophication and associated harmful algal blooms are expected to intensify with increasing global populations and changing climate. We conducted a literature review identifying 88 studies linking CAs to aquatic ecological responses since 2000. Most studies were conducted in North America (78%), primarily the United States (73%), within the framework of the USDA Conservation Effects Assessment Project. Identified studies most frequently documented macroinvertebrate (31%), fish (28%), and algal (20%) responses to riparian (29%), wetland (18%), or combinations (32%) of CAs and/or responses to eutrophication (27%) and pesticide contamination (23%). Notable research gaps include better understanding of biogeochemistry with CAs, quantitative links between varying CAs and ecological responses, and linkages of CAs with aquatic ecosystem structure and function.

Is eutrophication a global problem?

The eutrophication of surface waters has become an endemic global problem . Nutrient loadings from agriculture are a major driver, but it remains very unclear what level of on-farm controls are necessary or can be justified to achieve water quality improvements. In this review article, we use the UK as an example of societies’ multiple stressors on water quality to explore the uncertainties and challenges in achieving a sustainable balance between useable water resources, diverse aquatic ecosystems and a viable agriculture. Our analysis shows that nutrient loss from agriculture is a challenging issue if farm productivity and profitability is to be maintained and increased. Legacy stores of nitrogen (N) and phosphorus (P) in catchments may be sufficient to sustain algal blooms and murky waters for decades to come and more innovation is needed to drawdown and recover these nutrients. Agriculture’s impact on eutrophication risk may also be overestimated in many catchments, and more accurate accounting of sources, their bioavailabilities and lag times is needed to direct proportioned mitigation efforts more effectively. Best practice farms may still be leaky and incompatible with good water quality in high-risk areas requiring some prioritization of society goals. All sectors of society must clearly use N and P more efficiently to develop long-term sustainable solutions to this complex issue and nutrient reduction strategies should take account of the whole catchment-to-coast continuum. However, the right balance of local interventions (including additional biophysical controls) will need to be highly site specific and better informed by research that unravels the linkages between sustainable farming practices, patterns of nutrient delivery, biological response and recovery trajectories in different types of waterbodies.


Eutrophication is characterized by excessive plant and algal growth due to the increased availability of one or more limiting growth factors needed for photosynthesis (Schindler 2006), such as sunlight, carbon dioxide, and nutrient fertilizers.


The most conspicuous effect of cultural eutrophication is the creation of dense blooms of noxious, foul-smelling phytoplankton that reduce water clarity and harm water quality (Figure 2).


Given the widespread extent of water quality degradation associated with nutrient enrichment, eutrophication has and continues to pose a serious threat to potable drinking water sources, fisheries, and recreational water bodies.


Despite dramatic improvements in water quality as a result of large-scale efforts to reduce nutrient enrichment (e.g., Clean Water and Safe Drinking Water Acts in the 1970s), cultural eutrophication and concomitant HABs continue to be the leading cause of water pollution for many freshwater and coastal marine ecosystems and are a rapidly growing problem in the developing world (Smith & Schindler 2009).

References and Recommended Reading

Arend, K. K. et al. Seasonal and interannual effects of hypoxia on fish habitat quality in central Lake Erie. Freshwater Biology 56, 366-383 (2011).

What happens to fish in eutrophication?

Eutrophication can lead to hypoxia (“dead zones”), causing fish kills and a decrease in aquatic life. Excess nutrients can cause harmful algal blooms (HABs) in freshwater systems, which not only disrupt wildlife but can also produce toxins harmful to humans.

How can farmers improve nutrient management practices?

Adopting Nutrient Management Techniques: 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. 3,4.

What nutrients do farmers use to grow food?

Farmers apply nutrients on their fields in the form of chemical fertilizers and animal manure, which provide crops with the nitrogen and phosphorus necessary to grow and produce the food we eat. However, when nitrogen and phosphorus are not fully utilized by the growing plants, they can be lost from the farm fields and negatively impact air …

What is the most harmful gas to farm fields?

Nitrogen can be lost from farm fields in the form of gaseous, nitrogen-based compounds, like ammonia and nitrogen oxides. Ammonia can be harmful to aquatic life if large amounts are deposited from the atmosphere to surface waters. Nitrous oxide is a potent greenhouse gas.

What happens to phosphorus and nitrogen in water?

This excess nitrogen and phosphorus can be washed from farm fields and into waterways during rain events and when snow melts, and can also leach through the soil and into groundwater over time. High levels of nitrogen and phosphorus can cause eutrophication of water bodies.

What are the effects of agriculture on the environment?

Agricultural pollution also leads to air pollution. Many machines used for agricultural purposes emit harmful greenhouse gases like CO2 which in turn can lead to global warming. Moreover, farm animals emit large amounts of methane which is considered one of the most harmful greenhouse gases.

How does agriculture affect human health?

There are severe effects of agricultural pollution on human health. Through an excessive use of fertilizer and pesticides, harmful chemicals can reach our groundwater. Thus, in higher amounts and in contaminated regions, drinking tap water can lead to serious health conditions. Moreover, agricultural pollutions can also cause the contamination …

How does fertilizer affect aquatic life?

Effects on aquatic life. There is also an adverse effect on the aquatic system from agricultural pollution. Since the excessive use of fertilizer can contaminate rivers with an excessive supply of nitrates and phosphates, the production of algae can be enhanced.

Why should farmers try to improve nutrition management?

Farmers should try to improve nutrition management so that fertilizer and pesticides are not used in excessive amounts in order to mitigate the agricultural pollution problem. This means to determine in a scientific way how much pesticides and fertilizer are necessary to get a reasonable crop yield.

Why are pesticides bad for the environment?

Excessive use of pesticides and herbicides. The excessive use of pesticides and herbicides in order to optimize yields has become a big problem for the environment. Pesticides and herbicides contain many chemicals that can impact the ecological system in an adverse manner.

What are the causes of water pollution?

Water pollution. Water pollution is another big problem which is caused by agricultural pollution. Through the excessive use of fertilizers and pesticides, many harmful substances will reach our lakes, rivers and eventually also the groundwater.

How does agricultural pollution affect plants?

Agricultural pollution can become a problem for parts of the local plants since invasive species could impact the population of native species in an adverse way which in turn can change the dynamics of the whole ecosystem.

Why is it so hard to meet the demand for accelerated agricultural productivity?

The reasons for this have to do with ecological factors. Global climate change is destabilizing many of the natural processes that make modern agriculture possible.

How do cattle damage soil?

Cattle and other large grazing animals can even damage soil by trampling on it. Bare, compacted land can bring about soil erosion and destruction of topsoil quality due to the runoff of nutrients. These and other impacts can destabilize a variety of fragile ecosystems and wildlife habitats. Chemical Fertilizer.

Where does nitrogen come from in fertilizer?

Roughly half the nitrogen in synthetic fertilizers escapes from the fields where it is applied, finding its way into the soil, air, water, and rainfall. After soil bacteria convert fertilizer nitrogen into nitrates, rainstorms or irrigation systems carry these toxins into groundwater and river systems.

What is the effect of nitrogen on soil?

In addition, fertilizer application in soil leads to the formation and release of nitrous oxide, one of the most harmful greenhouse gases.

How does irrigation affect water?

Irrigation causes increases in water evaporation, impacting both surface air temperature and pressure as well as atmospheric moisture conditions . Recent studies have confirmed that cropland irrigation can influence rainfall patterns not only over the irrigated area but even thousands of miles away.

What causes algae blooms in China?

Nutrient pollution is a causal factor in toxic algae blooms affecting lakes in China, the United States, and elsewhere. As excessive amounts of organic matter decompose in aquatic environments, they can bring about oxygen depletion and create “dead zones” within bodies of water, where nothing can survive.

What are the consequences of irrigation?

One of the most obvious consequences is the depletion of aquifers, river systems, and downstream ground water. However, there are a number of other negative effects related to irrigation.


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