Lawn Fertilizers & Ground Water

Ground water pollution is a growing concern. It occurs as toxic chemicals leach into water systems and build up over time. Lawn fertilizer contains several chemical nutrients that can soak through the soil and into ground water systems. Contaminated water can cause health problems for both humans and animals. Ground water contamination can be a particularly subtle threat because ground water is out of sight, so pollutants can be difficult to detect.

Fertilizer

• Fertilizers give plants the nutrients they need to grow. They come in a variety of forms, such as manure, sod and sprays. C. J. Rosen and B. P. Horgan of the University of Minnesota discuss how fertilizers pollute the environment in their article, "Preventing Pollution Problems from Lawn and Garden Fertilizers." Fertilizer sits on top of lawns, where rain and watering can easily wash it away. In urban areas, lawn runoff flows over concrete and asphalt until it enters storm drains or pools on soil, concentrating all of the chemical runoff. This then leaches into the soil.

Fertilizer Nutrients

• According to the website Basin Sod and Gravel, the main nutrients in fertilizer are nitrogen, phosphorous and potassium. Nitrogen encourages leaves to grow, and gives them a dark green color. Phosphorous helps plants transfer energy, especially during early growth periods as root systems take hold. Potassium aids cell wall growth, which is an important defense against insects and disease.

Ground Water

• Ground water flows in underground streams through geological formations called aquifers. These aquifers vary greatly in size, and a single aquifer can supply thousands of families with fresh drinking water. According to the Virginia Cooperative Extension, ground water is created when water from rain or irrigation soaks down through the soil, past root systems, into the saturated zone where ground water flows.

Water Contamination

• When runoff from fertilized lawns percolates through the soil into ground water systems, it carries with it the fertilizer's chemical nutrients. This creates plumes of contaminated ground water. Because ground water flows so slowly (only a few feet per month or even year, according to the Virginia Cooperative Extension), it can take decades for ground water to free itself of chemical contaminants.

Health and Environmental Effects

• Because ground water is often siphoned through wells for human consumption, pollution can cause health concerns. For example, according to the University of Minnesota, nitrates from fertilizer in drinking water cause methemoglobinemia in infants, which limits their ability to effectively use oxygen. Also, the New York Times reports that fertilizer-contaminated, nitrogen-rich water which makes its way into the ocean creates "dead zones" where life is unsustainable. This has both ecological and economical impacts, because local fisheries suffer when wildlife disappears.

Prevention

• The City of Olympia offers some guidelines to help ensure that runoff does not cause ground water contamination. They recommend applying fertilizer outside of heavy raining seasons, which vary by location. Buying organic fertilizer, or ones which use water-soluble nitrogen, also helps.