How Do Nitrogen & Phosphors Fertilizers Affect Water?

Nitrogen

• Nitrogen is part of all living cells and an important part of all proteins. Plants need nitrogen for growth, seed and fruit production and photosynthesis. Although legumes like beans and alfalfa pull nitrogen from the air, most plants take up nitrogen from the soil through their roots. Nitrogen deficiency causes yellowed leaves, stunted growth and poor fruit and seed yield.

Nitrogen Contamination

• Precipitation and irrigation cause excess nitrogen in the soil to leach downward through the soil directly into the groundwater or to run off the soil surface. The run-off finds its way to storm drains, creeks and rivers that also feed into the groundwater. According to researchers at the University of Vermont, "Water with over 10 parts per million nitrate-nitrogen can cause methemoglobinemia, an inability to use oxygen in infants."

Phosphorus

• Phosphorus affects plant growth, photosynthesis, flower production and root development. As rocks and other mineral deposits weather and break down over time, phosphorus is released into the soil. In many places, especially urban areas, this process can be slow or nonexistent depending on the availability of deposits. Although plants do not need the same quantities of phosphorus that they need of nitrogen, they can easily deplete the phosphorus in the soil before nature replaces it, prompting the need for fertilizers.

Phosphorus Contamination

• Phosphorus is not water-soluble like nitrogen is and does not leach through easily once it has been worked into the soil. However, fertilizers left on the surface easily run off into nearby waterways. Additionally, animal waste, grass clippings and tree leaves add significant amounts of phosphorus that also runs off into the waterways. The naturally occurring phosphorus combined with the fertilizer phosphorus creates an algae bloom in the water and depletes the oxygen in the water, suffocating the fish, plants and other wildlife and contaminating the water supply.

Prevention

• Although misuse of fertilizers can have disastrous effects, proper application improves plant health without harming the environment. Synthesized or chemical fertilizers require a little water at application time to begin the process of releasing the nutrients from the fertilizer into the soil. Work the fertilizer into the soil and do not overwater or apply before a big rain storm, which would begin the run-off problems. Only apply the amount of fertilizer recommended by the manufacturer.