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Describe agricultural practices that cause environmental damage.

Impacts of Agricultural Practices

Billions of people on Earth require significant amounts of agricultural products on a daily basis. As such, agricultural activities are ongoing on all continents and those activities can potentially impact the environment in a variety of ways. Depending on the type of agriculture, the impacts on the environment can be minimal or very significant. Loss of biodiversity, desertification of soil, water pollution, and air pollution are all associated with agriculture. Much work has been done to reduce these impacts, but much remains to be done to make agriculture less damaging to the environment and human health.

Explore the tabs below. Which impact do you think is the most important? Why?

Loss of Biodiversity
Desertification
Water Pollution
Air Pollution

Loss of Biodiversity

a landscape of green terraced fields on rolling hills, with a small village in the middle. The sky is partly cloudy — **Clearing large swaths of land to grow monocultures reduces natural habitats, which can cause a loss of biodiversity in the area.**

Farmers plow millions of acres of soil annually to grow crops. Large swaths of habitat are impacted along with the many species that inhabit those areas, leading to fragmentation and a reduction of plants and animals in the area.

Keep in mind that one of the most important aspects of biodiversity is the variation in genes within each species. When members of a species are eliminated, genetic diversity is reduced as well. This inhibits the species’ ability to respond to environmental change.

When land has been cleared to raise livestock, natural ecosystems and the organisms that live in those ecosystems are pushed back from areas where they have previously lived.

Predators in these natural areas may not have enough prey due to the reduced size of their habitat. Sometimes, these predators will prey on livestock. Ranchers have been known to kill these predators to protect their livestock. This type of conflict illustrates one of the side effects of agricultural production.

Desertification

A close-up view reveals a surface covered in dry, cracked mud. — **Desertification is extreme and permanent. It cannot be reversed.**

Soil desertification is an extreme and permanent reduction in the productivity of arid, semiarid, and seasonally dry areas. Improper plowing techniques, overgrazing by livestock, and poor irrigation practices all contribute to desertification. Forty-one percent of Earth’s lands are susceptible to this condition and 10-20% of those lands, about 6 billion hectares, are already degraded, affecting around 2 billion people.

When soils in dry areas are irrigated too heavily, the water evaporates before it can percolate into the soil. This rapid evaporation leaves only the salts in the water behind (even the freshest of water has some salts), resulting in soil that is too salty (saline) for plants to grow. This is called soil salinization. Soils that suffer from salinization become progressively less productive leading to diminishing yields.

Water Pollution

A narrow water canal is centrally positioned in the image, its still waters reflecting the blue sky and clouds above. — **Fertilizers are applied to soils. Then over-watering can cause these fertilizers to runoff agricultural lands into waterways.**

Some soils are continually lacking the nutrients needed for the types of crops being grown. When this happens, farmers often add significant quantities of fertilizer to soils. Fertilizers contain one or more of the necessary nutrients missing from the soil, usually nitrogen or phosphate. Fertilizer can be inorganic, chemical formulations of these nutrients, or organic, formed by plant and/or animal waste.

Adding fertilizer to soil is not a perfect solution, however, because fertilizer can runoff into our waterways and leading to cultural eutrophication, a type of water pollution in which algae populations explode due to the influx of excess nutrition. When the nutrition runs out, the algae die off and the decomposition of the dead algae causes the dissolved oxygen levels in the waterway to drop to dangerously low levels.

Groundwater can become polluted when fertilizers, chemicals, animal waste, and other pollutants percolate down through soil layers into the aquifer.

Once the groundwater becomes polluted, it is very difficult to remove the pollutants. The best course of action is to avoid contaminating the aquifer.

An aerial view captures a vast, open landscape with a large circular green field at its center, contrasting sharply with the arid terrain. — **If you happen to fly over the Great Plains in the United States, you might notice these green patches on the ground. These are irrigation patches.**

Most of our water is used by agriculture and industry. When farmers irrigate a piece of land, they often use a form of sprinkler that spins in a very large circle, creating these irrigation patches. The use of large amounts of water by agriculture can deplete aquifers faster than they can recharge.

In much of the developed world, livestock are raised in confined animal feeding operations (CAFOs). In these types of farms, large amounts of animals are raised in a very small area.

In the United States, livestock produce 460 million tons of waste/year. This waste can leak into surface waters, contributing to fish die offs, contaminating the waterways with pathogens, and the nitrogen in the waste can cause the proliferation of algae. The EPA considers animal-based agriculture the most widespread source of pollution in U.S. rivers.

Air Pollution

An aerial image shows a field being burned, emitting smoke that blankets the area. Lines of crop remnants indicate recent harvest. — **Burning forests or agricultural fields can release extra carbon dioxide into the atmosphere.**

Slash-and-burn deforestation and other changes in land use are estimated to release 1.6 billion tons of carbon/year into the atmosphere, which contributes to climate change by intensifying the greenhouse effect.

Livestock release 30 million tons of methane/year via passing gas. Methane is many times more potent than carbon dioxide as a greenhouse gas, so this can be significant and is thought to be as much as 3% of greenhouse gases.

Additionally, tractors, vehicles, hauling trucks, trains, grain barges, and other machinery related to agriculture can release pollutants into the air if they are powered by fossil fuels.

Agriculture is necessary to support the billions of humans and other animals on Earth. If done carefully and thoughtfully, environmental impacts can be minimized.

Essential Knowledge

Agricultural practices that can cause environmental damage include tilling, slash-and-burn farming, and the use of fertilizers.

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