Environmental Pollution Education

Agricultural Pollution: Sources and Solutions

Agricultural pollution is the contamination we release into the environment as a byproduct of growing and raising crops and livestock. Prevention of environmental pollution from agricultural activity is a multi-faceted problem that we’ll break down for you here.

In this article we’ll answer the following questions:

Here’s a quick background on agricultural pollution for context:

What is agricultural pollution?

About 40 percent of all land in the United States is used for agriculture, and the agriculture industry generates more than 10 percent of the nation’s greenhouse gas emissions. The way we grow, raise, transport, process, and store crops and other farm products has huge effects on the environment. Agricultural pollution is the contamination we release into the environment as a byproduct of growing and raising crops and livestock. 

What are the biggest sources of pollution from agriculture, and what can we do to reduce that pollution? 

What are the biggest sources of agricultural pollution?

Nutrient Runoff

Nutrient runoff is: 

When nutrient-rich material like fertilizer or manure is applied to land, it doesn’t always stay exactly where it’s applied. It can filter through the soil into groundwater or run off when it rains into local waterways. Runoff from agricultural lands is a leading cause of pollution and reduced water quality in rivers, streams, lakes, and wetlands, and can cause serious issues in freshwater and marine ecosystems.

History of This Problem: Nutrient runoff became a problem in the 20th century when we moved to mass-farming. 

Plants need the nutrients nitrogen and phosphorus to grow, but when under “mono-cropping” where just one crop is planted over a large area of land, nutrients in the soil are depleted. In the 20th century with the start of industrial farming practices, farmers began to apply synthetic nitrogen fertilizers to farmland. According to the United States Environmental Protection Agency (USEPA), about 12 million tons of nitrogen and four million tons of phosphorus fertilizer are applied yearly to crops in the continental United States. 

The problem with nutrient runoff is…After nutrients like nitrogen and phosphorus get into waterways, they can cause algae to grow. Algae is an underwater organism that can photosynthesize. When the algae die, bacteria break them down. This process—called eutrophication—uses up oxygen and produces large amounts of carbon dioxide, making it so that there is less oxygen available for marine life. If they can’t swim away, fish and other wildlife become unhealthy or die without oxygen. This process can also kill off seagrasses and take away important habitats for marine creatures.

Chemical Pesticides

Many farmers spray pesticides made of toxic chemicals on their land to keep away unwanted weeds, insects, rodents, and fungi. Like excess nutrients, pesticides applied to agricultural land can run off into waterways. About a half a million tons of pesticides are applied in the U.S. every year, and pesticides are regularly found in 90 percent of streams and rivers.

Humans can be exposed to chemical pesticides through contaminated water, air, and food. When humans come into contact with these chemicals, it can cause negative health impacts. Pesticide exposure has been linked to chronic diseases like endocrine (hormone) and neurological disorders as well as cancer. Children are especially vulnerable to exposure to these chemicals.

Pesticides are also harmful for pollinators like insects and birds. Pollinators (and especially honeybees) are incredibly important for plants. About 90% of all flowering plants rely on pollinators to survive. Exposure to pesticides can kill pollinators or have other effects that make it harder for them to thrive.

Animal Agriculture

Animal agriculture is the second largest source of human-caused greenhouse gas emissions and is a major cause of water and air pollution. A whopping 70 billion animals are raised for human consumption globally each year. 

Livestock farming is the largest source of global water pollution, and most of that pollution comes from animal waste. Livestock manure is applied to land, but before this happens, it sits in manure lagoons which contain antibiotics residue, chemicals, and bacteria decomposing the waste. These lagoons sometimes leak or have spills that cause the material inside to leach into soil and groundwater. 

Livestock and manure also cause air pollution. Manure emits ammonia, which combines with other air pollutants, like nitrogen oxides and sulfates, to create small particles that can be dangerous for human health when inhaled.

There’s another large source of emissions in animal agriculture: cow burps and gas, sometimes called by the fancy name “enteric fermentation.” It’s part of the digestive process of animals like cows, sheep, and goats, where gut microbes break down and ferment grass the animals eat. This produces methane, a greenhouse gas that is more than 28 times more potent than carbon dioxide. Enteric fermentation is the largest source of greenhouse gas emissions in agricultural production, generating about 164 million metric tons of carbon dioxide-equivalent emissions each year. 

What are the solutions to agricultural pollution?

As our global population continues to grow and we need more food to feed people, we must make shifts in our agricultural practices to reduce pollution and protect human health and the health of the planet. Here are some solutions to pollution from agriculture:

  • Managing Nutrients Better: Farmers can apply nutrients like fertilizer and manure in the right amount, at the right time of year, with the right method, and with the right placement to prevent filtration into soil and runoff into waterways. Using technology to track fertilizer application can help farmers better manage the way they apply nutrients.
  • Making Changes in the Way Crops are Planted and Farmed: Farmers can plant certain types of crops to cover the ground year-round and make it so that there isn’t bare ground on farm fields, plant trees and shrubs along the edges of fields as a buffer between fields and water bodies, and till fields less often to improve soil health and prevent erosion and runoff.
  • Controlling Livestock Access to Waterways: Farmers and ranchers can install fences along waterways, blocking the animals’ access to help restore stream banks and prevent excess nutrients from entering the water.
  • Creating a Manure Management Plan: Having a manure management plan can help replace fertilizer application, keep soil healthier, and avoid the risk of spills and water contamination. 
  • Working Together to Protect Watersheds: A wide range of people (including farmers) and organizations can work together across watersheds where farms are located to reduce pollution from agriculture. A watershed is an area of land that contains a common set of streams and rivers that all drain into a single larger body of water.

What can you do to help?

There are simple steps that individuals can take to support sustainable farming practices, including:

  • Choose organic fruits and vegetables instead of conventional ones when you can to support sustainable practices.
  • Buy food from local farmers at a farmers’ market or co-operative to support local agriculture and sustainable growing methods.
  • Grow your own food, without chemicals.
  • Pay attention to farm policy, and support practices that are better for the environment.

Team Writer