Ethanol and Water
Corn farming, ethanol production, and water quality

Corn production is a water intensive process.

Corn farming in the United States is extremely fertilizer- and pesticide-intensive. Due to the recent expansion of ethanol production and land acreage allotted to corn farming, water quality is seriously threatened by the increased use of chemical fertilizers and pesticides.

Excessive fertilizer runoff from corn cultivation contributes to the ever growing dead zones in the Gulf of Mexico and the Chesapeake Bay, areas so depleted of oxygen that they cannot sustain life. Moreover, pesticide leaching threatens the health of humans and wildlife as traces of these chemicals are found in groundwater used for drinking.

  • Corn, as compared to all other ethanol-producing crops, has the greatest application rate of both fertilizers and pesticides per hectare.
  • Corn production consumes 40% of all commercial fertilizers used on crops in the United States; commercial nitrogen is applied to 98% of corn fields and commercial phosphate to 87%.
  • The US Department of Agriculture estimates that corn crops are treated with 138 pounds of nitrogen fertilizer per acre and 58 pounds of phosphorus fertilizer.
  • The application rates of nitrogen fertilizer are often more than twice as much as the crop absorbs. Between 40 and 60% of the fertilizer applied to corn remains on the field as waste. This waste leaches into groundwater, streams and rivers, contaminating drinking water supplies and creating aquatic dead zones.
  • According to the US Department of Agriculture, 95.8% of corn crops are treated with some kind of pesticide. The National Agricultural Statistics Service estimates that in 2005, corn crops consumed 157 million pounds of herbicides and 4.8 million pounds of insecticides.

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    Pesticide and herbicide use
    Corn farming and chemical use

    Growing corn for ethanol production is a chemical intensive process.

    In the United States, commercially-grown corn is an extremely chemical-intensive crop. With more corn crops being planted for the production of biofuels, there is an increasing use of insect killers, weed-killers, plant growth regulators and other types of pesticides. These chemicals are applied throughout the growing season by a variety of different methods ranging from aerial application (crop dusting) to being dissolved in water and sprayed.

    Herbicides are by far the most commonly used agrochemicals in corn farming and are applied to 96% of U.S. corn acreage. They are the most prevalent (both in terms of frequency and concentration) agricultural pesticides found in surface and drinking waters throughout the United States.

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    Fertilizer use
    Growing corn requires heavy fertilizer application

    Over-use of conventional fertilizers can dramatically affect the quality of our environment.

    Corn farming in the United States uses more fertilizer than any other commodity crop, resulting in widespread harm to the environment. Fertilizers contain water-soluble nutrients, such as nitrogen and phosphorus, which enter rivers and streams that ultimately flow into larger bodies of water. The nutrients enter the rivers by infiltrating groundwater or through surface runoff in soil particles, posing serious threats to human health and to entire ecosystems.

    As ethanol production mandates push corn prices higher, farmers are increasingly abandoning the traditional corn-soybean rotation for corn monoculture, known as corn-on-corn or corn-after-corn. Corn monoculture leads to greater soil depletion, which leads farmers to apply even larger quantities of fertilizer, perpetuating a growing cycle of environmental degradation.

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    Eutrophication
    Excess nutrients can lead to eutrophication

    Fertlizer intensive activities, such as corn production, create excess nutrients.

    Eutrophication is a process whereby excess nutrients enter the water system and spur excessive plant growth called algal blooms. Corn farming in the United States uses large amounts of fertilizers that are not fully absorbed by the crops, resulting in leached nitrates and phosphates that infiltrate water bodies through ground water and surface water runoff. As the runoff reaches large bodies of water, the nutrients make the algae flourish. Overgrown water plants and algae consume the oxygen in the water, suffocating fish and other species. When the algae eventually die, oxygen is required by bacteria to decompose or break down the dead algae.

     A cycle then begins in which more bacteria decompose more dead algae, consuming even more oxygen in the process. Nutrients can come from many sources, such as fertilizers applied to agricultural fields, golf courses, and suburban lawns; deposition of nitrogen from the atmosphere; erosion of soil containing nutrients; and sewage treatment plant discharges. Water with low oxygen levels is called hypoxic, and water with no oxygen, an extreme form of hypoxia, is considered anoxic.

    As other species die, the area becomes lifeless and is labeled a “dead zone.” Seasonal dead zones have expanded in the Gulf of Mexico and the Chesapeake Bay. The ethanol boom and associated increased fertilizer runoff have fed the growth of these hypoxic areas.

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