WHAT IS FERTILIZER
Fertilizer is a word that most everyone knows, but what it is and what does it do?
Fertilizer is basically food for plants in a readily available form. Plants, just like humans, need a variety nutrients to grow and thrive. While humans get nutrients from the different foods (meat, vegetables, fruits, dairy, grains) they eat, plants obtain most of the nutrients they need from the soil. Many times the different types of soil don’t have the nutrients necessary for the plant to grow and thrive or the nutrients are bound to the soil in a form that makes it difficult for the plant to use. That’s where fertilizer comes in.
Fertilizer is used to supply plants with the nutrients they need, primarily nitrogen, phosphorus, and potassium, in a form that is easy to uptake and use by the plants roots. It is typically added to the soil when a newly planted seed or young plant is started to help the plant become established. Fertilizer can or may be added to the soil throughout the life of the plant to help keep it healthy and growing strong. But over-fertilizing can be a bad thing. Too much fertilizer can actually kill the plant and excess fertilizer can run-off into streams and lakes causing toxic algal blooms that are harmful to aquatic life.
When we apply fertilizer to our yards, we are adding nutrients, which all plants need to survive and grow. What we don’t always consider, though, is that our soils may already have sufficient levels of these nutrients. Brand-new lawns or areas with very poor soils might be lacking in nutrients, but most established lawns are not. When we fertilize these areas anyway, the nutrients (mainly nitrogen and phosphorus) that aren’t able to be used up by the lawn then run-off with the next rain and end up in our streams and reservoirs where they feed algae. Not only does algae give the water a greenish hue, but its fast growth and death cycle also robs the water of oxygen, which can be harmful to fish and other aquatic life. Excess nutrients in the water and the resulting algal blooms can also cause result in the production of algal toxins and strange tastes and smells (taste and odor compounds) in the water. It takes just one (1) pound of phosphorous entering a waterway to produce 500 pounds of algae.
You might wonder if organic or phosphorus-free fertilizers are the solution to preventing algal blooms or other risks to the environment. While those are certainly very important considerations and decisions when selecting fertilizer for your lawn (always use a phosphorus-free fertilizer!), that's not the whole fertilizer story, nor the end of harmful fertilizer impacts. Allowing too much nitrogen into waterways can be just as harmful to water quality as phosphorus. Nitrogen, or nitrate, also contributes to the excessive growth of algae and other plants. Nitrate, a water soluble form of nitrogen, is the form of nitrogen normally used by plants. Concentrations of nitrate in lakes and streams greater that 5 milligrams per liter (measured as nitrogen) can cause excessive growth of algae and other plants, just as phosphorus does. This growth can lead to rapid aging or “dying off” of lakes. It can also lead to low dissolved oxygen levels that in turn makes it hard for aquatic life to survive. Exposure to high levels of nitrate is also dangerous for animals and humans even without the consideration of algae growth and oxygen impacts. If humans consume water (drinking water) with a nitrate-nitrogen concentration greater than 10 milligrams per liter it can lead to a condition called methemoglobinemia or “blue baby syndrome” in infants and other negative health impacts. The best choice you can make is to only use the type and amount of fertilizer your lawn needs – test your soil first!
The overuse of fertilizers also contributes to coastal areas known as "dead zones," where marine life is suffocated, stressed, and even killed by a low concentration of oxygen. The excess nitrogen and phosphorous found in fertilizers runs off into rivers and streams, eventually making its way to estuaries. The Chesapeake Bay and the Delaware Bay on the east coast both have identified "dead zones," and although river cleanup efforts and regulatory standards have improved conditions, much effort is still needed to reduce the amount of nutrients flowing into our rivers and streams every day.
Learn more about dead zones in this article from Business Insider.