Nutrient Management

What are nutrients?

Nutrients are compounds that the agricultural community uses to stimulate and enhance the growth of food crops and animals. Nitrogen and phosphorus are the most common nutrients with which people are familiar. Phosphates, a family of naturally occurring compounds that combine phosphorus and oxygen, are present in all living organisms, animal and vegetable. Phosphorus is an essential nutrient needed to support life.

Given their essential role in life processes, many phosphates are “Generally Recognized As Safe” as a food ingredient by Health Canada and the U.S. Food and Drug Administration

Where do phosphates come from?

Excellent sources of phosphorus-laden rock are ancient sea beds. The rock is mined, refined, and purified. The resulting phosphorus-based products are used as ingredients in fertilizers, detergents, baking powders, toothpastes, cured meats, evaporated milk, soft drinks, processed cheeses, pharmaceuticals, and water softeners.

What is eutrophication?

Nutrients such as nitrogen, phosphorus, carbon, and silicon are essential for algae to grow. Our water bodies provide an important environment for the growth of algae that provides a rich food source for fish and other animals in the aquatic food chain. These nutrients find their way into the waterways through agricultural runoff, soil erosion, and discharges from the treatment of human waste.

While nutrient enrichment is a natural process, too much enrichment can cause algae to grow uncontrollably, disturbing the balance among organisms in the food chain. Fortunately, these aquatic environments are very resilient and this over-enrichment, or eutrophication, can be managed.

What is nutrient management?

To prevent excessive amounts of nutrients from being released into our waterways, plans are put in place to manage the amount of fertilizers used in agriculture. Also, animal production operations are exploring ways to manage runoff of manure that is often rich in nutrients.

What is being done about the nutrient management problem?

Several steps to minimize excessive amounts of nutrients released to the environment have been taken. At wastewater treatment plants, several hundred million pounds of phosphorus have been eliminated annually from our rivers and streams. Phosphate detergent bans, once thought to provide a quick reduction in phosphates in the environment, were enacted by several states. However, the “efficacy of this remedy continued to be debated throughout the 1970’s and 1980’s” according to a U.S. Geological Survey Review of Phosphorus Control Measures. It is unlikely that further removal of phosphates from consumer products will have a significant impact on nutrient management efforts.

In addition, farmers are now required in most states to prepare nutrient management plans. These plans specify the appropriate amount of nitrogen and phosphorus required for individual crops without applying excessive nutrients that can migrate into our waterways.

Recovery and recycling of phosphorus from wastewater sludges and animal waste show promise. The Phosphate Forum of the Americas has sponsored research into technologies that will remove phosphorus and allow the material to be recycled. Feasibility studies have been completed for phosphate recovery and removal from municipal wastewater treatment plants, as well as potato and animal production operations. Research continues on technical and economic methods of phosphorus recovery and recycling.

References:

1Litke, David W., 1999, Review of Phosphorus Control Measures in the United States and Their Effects on Water Quality, U.S. Geological Survey, Water Resources Investigations Report 99-4007, 38 p.