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.
What is algae?
Algae are a very diverse group of aquatic plants/organisms that are capable of producing oxygen through photosynthesis. They can be very tiny (microscopic) or large seaweeds like giant kelp. Phytoplankton, pond scum, or algal blooms on lakes are a few of the different types of algae that most people are familiar with, but there are thousands of different species across the world.
Algal blooms, which are known for creating toxic conditions in lakes and oceans, occur because of the fast growth of certain algae leading to the production of toxins. In Lake Erie, a type of cyanobacteria called microcystin is the primary toxin producer. In normal conditions, microcystin produce the toxins in very small amounts to protect themselves from being eaten by small animals.
Algae get a bad rap for the toxic conditions created during algal blooms. The problem however is us! Nutrient pollution, excess phosphorus and nitrogen from either fertilizers or untreated wastewater causes the uncontrolled growth of the algae that lead to the algal blooms. Believe it or not, but algae are crucial to the environment! They are a major part of the food chain, oil and petroleum products, and most importantly they produce anywhere between 50% to 70% of the oxygen in the air we breathe.
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 or low phosphorus!), 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!