The Phosphorus Cycle

Phosphorus (P) is a naturally occurring, essential nutrient for both plant and animal growth. P is found in the soil, animal manure, most fertilizers, storm water and human waste products. It is often found to be the plant growth-limiting nutrient in lakes and other water bodies. As long as P is unavailable or in low amounts, plant growth in aquatic systems will stay in check. Once P is freely available, plants can grow to excessive levels. This potentially severe increase in plant growth (algae and rooted plants) is usually associated with a condition known as cultural eutrophication, which eventually leads to declining water quality. Both technical and educational programs are needed to inform the public and targeted groups about phosphorus applications, use, reduction and best management practices to decrease P runoff.


Phosphorus cycle. Photo credit:

In 2007, the Michigan Department of Environmental Quality released a report from a statewide Phosphorus Advisory Committee to control phosphorus loading into surface waters. Many of the recommendations cited MSU Extension and partner organizations as major resources to help implement these recommendations.These recommendations were directed to both urbanizing and rural environments.

Improved phosphorus management will help to maintain and improve Michigan’s water resources so that current and future generations can enjoy environments that provide recreational opportunities, aesthetics, and quality water. 

Additional information:

Agriculture Phosphorus management and water quality protection in the Midwest