Too Many Nutrients are a Problem for Our Water

When you think of the word nutrients, what comes to mind?  Most likely it is nutrition and the food that we fuel our body with as we carry out our lives.  Perhaps you even think of it on a smaller scale and think of substances like carbohydrates, fats, and proteins.  If we generalize the definition of nutrients, we can define them as the substances that are essential for life and growth.  Consequently, nutrients don't just refer to things that people and animals eat but also to things that help plants grow.  Those same nutrients that help plants grow can also become pollution in our water.

When it comes to nutrients for plant growth as well as nutrient pollution, we need to think on more of a molecular scale.  Generally, we apply things like fertilizers, compost, and manure to our gardens, lawns, pastures, and crop fields to help make sure the plants have everything that they need to grow. Taking a closer look, molecules containing nitrogen, phosphorus, and potassium are major components of all of these amendments and are some of the nutrients that are actually "feeding" the plants. 

Just like people and animals can only consume so much food at once, plants can only use a limited amount of nutrients at one time.  Any nutrients that aren't taken up by the plants are vulnerable to becoming nutrient pollution by way of leaching, erosion, or stormwater runoff.  Consequently, it is essential to apply fertilizers, compost, and manure based on the plant's needs.  But how do we know what the right amount of nutrients is?  The first step to applying the correct amount of nutrients is taking a soil test.  Soil tests will tell you the current levels of phosphorous and potassium in the soil and will estimate the appropriate amount of nitrogen, phosphorous, and potassium based on specific plant needs.  It is crucial to follow these recommendations and not to overapply nutrients.  Following the recommendations will result in the optimal plant response.  Overapplying nutrients will not create better looking or producing plants and is much more likely to be a waste of money and a source of pollution for waterbodies in urban, suburban, and rural areas.

So, if nutrients are so good for plants, then why are they considered a pollutant in our water?  Just like nutrients help our terrestrial plants grow, they also stimulate the growth of aquatic plants in ponds, lakes, streams, rivers, and other surface water bodies.  The challenge is that when extra nutrients, especially phosphorus, reach our waterbodies, they can boost the growth of algae and aquatic plants and result in accelerated eutrophication.  While eutrophication is the natural aging of surface water bodies because of nutrient enrichment, adding unnecessary supplementary nutrients can speed up this process and cause many undesirable effects like oxygen depletion, death of aquatic organisms, and harmful algae blooms which can restrict water use for fisheries, recreation, industry, and drinking. 

According to the United States Environmental Protection Agency, nutrient pollution is one of the most widespread and challenging problems in our water bodies.  While some of the primary sources of nutrient pollution include agricultural runoff and stormwater runoff, nutrients can also be added into our waterways from human wastewater systems and the use of fossil fuels.  To learn more about nutrient pollution in our waterways, how nutrients travel from land to water, and what can be done to prevent this from happening, watch the video, What Are Nutrients and Why Are They Stormwater Pollutants?

Sources and Additional Information

Beegle, Douglas, and Les A. Lanyon. "A Nutrient Management Approach for Pennsylvania: Introduction to the Concepts." Penn State Extension, 1 September 2017.

Beegle, Douglas. "Managing Phosphorus for Agriculture and the Environment." Penn State Extension, 1 September 2017.

Brackenrich, Justin, and Rachel Milliron . "Interpreting Your Soil Test Reports." Penn State Extension, 17 April 2023.

"Nutrient Pollution." United States Environmental Protection Agency, Environmental Protection Agency.  Accessed 10 October 2024.