Agricultural Water Pollution: Understanding The Impact Of Farming

Agriculture is the single largest user of freshwater resources, accounting for 70% of total water consumption worldwide. However, it is also a major cause of water pollution. Pesticides, fertilizers, and animal manure can contaminate both groundwater and surface water, as can organic livestock wastes, antibiotics, silage effluents, and processing wastes from plantation crops. This pollution can have negative impacts on people's health and the environment.

Pesticides and fertilizers

Agriculture is the leading cause of water quality impacts to rivers and streams, the third leading source for lakes, and the second largest source of impairments to wetlands.

Fertilizers are also a major source of water pollution. They have a high concentration of nutrients, specifically nitrogen and phosphorus. When too much fertilizer is used in crop production, the excess remains in the soil and is eventually washed off during irrigation or rainfall, making its way into water resources. This can alter the biochemistry and microbial activities in the soil, negatively impacting plants.

To reduce the risk of water pollution from pesticides and fertilizers, it is important to limit and optimize the type, amount, and timing of their application to crops. Establishing protection zones along surface watercourses and efficient irrigation schemes can also help mitigate the migration of these pollutants into water bodies.

Animal waste

Animal agriculture is one of the largest drivers of water pollution. This is due to the overwhelming amount of waste created as a byproduct of the production of animal-derived food. Factory farms, in which animals are packed together on small areas of land by the thousands or tens of thousands, play a large role in polluting water, as the waste from these animals makes it into waterways, groundwater, and the open ocean. The waste is high in nutrients, including nitrates, which have now become the most common contaminant in the world’s groundwater aquifers. In recent years, veterinary medicines have also made their way into our drinking water due to their heavy use within animal agriculture.

The waste produced by animal agriculture encourages the formation of algal blooms and dead zones. When the nutrients in the waste, such as phosphorus and nitrogen, make their way into the water, they increase the likelihood and severity of algal blooms. These algal blooms can contribute to disease outbreaks and negatively impact economies that depend on clean water.

Growing crops to be fed to animals is also a major contributor to water pollution due to the sheer size of the industry, the many different chemicals employed, and the enormous amount of fresh water it uses. Of the calories from crops produced around the world, only 55 percent go directly to humans for consumption. About 36 percent of calories from crops are fed to animals raised for meat.

Soil erosion

Agriculture is the single largest user of freshwater resources, using 70% of all surface water supplies. It is a cause of water pollution through the discharge of pollutants and sediment to surface and/or groundwater. One of the ways in which agriculture causes water pollution is through soil erosion.

Agricultural practices that contribute to soil erosion include the excessive use of fertilizers and the misuse of pesticides. When fertilizers are overused, they can increase the amount of nutrients in the soil, leading to nutrient runoff into water bodies. This can cause excessive algae growth, which can deplete oxygen levels and harm aquatic life. Similarly, the misuse of pesticides can result in their runoff into water sources, posing risks to both human health and the environment.

To mitigate soil erosion, farmers can implement a range of conservation practices. These include contour plowing, which involves plowing along the contour lines of the land to reduce water runoff and soil loss. Another practice is the use of cover crops, which help to hold the soil in place and prevent erosion. Terracing, or creating leveled steps on sloped land, can also be employed to slow down water flow and reduce soil erosion. By adopting such practices, farmers can help minimize the impact of agriculture on water pollution caused by soil erosion.

Irrigation

In the West and Southwest, agriculture is the single biggest user of limited ground and surface water resources. Since 2000, the region has faced its most severe drought in over 1,200 years, forcing a reconsideration of how water is distributed. With 55% of the Colorado River (the region's largest water source) going directly to forage crops for cattle, scientists warn that farm policy needs to change to incentivise farmers to grow less thirsty crops.

The expansion of fruit and nut orchards has removed so much groundwater from aquifers in California and other states that supplies are either unavailable or very limited.

Water consumption

Agriculture is the single largest user of freshwater resources, using a global average of 70% of all surface water supplies. This water is used for irrigation, which can lead to salinization and waterlogging of the land.

The Food and Agriculture Organization of the United Nations (FAO) works closely with countries and other organizations to monitor, control, and mitigate pollution loads from agricultural activities. FAO defines water quality-related activities in two categories: agriculture as a water polluter and agriculture as a victim of water pollution.

In addition to the direct contamination of water sources, agriculture can also cause water pollution through net loss of soil by poor agricultural practices, such as soil erosion, nutrient loss, and the runoff of pesticides and other contaminants. This can lead to the impairment of water quality, making it unsafe for human consumption and harmful to the environment.

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