Don’t Fertilize the Lake
May 3, 2015
As I write this, my backyard has not yet come out from under the snow. When it does, it’s going to be brown and matted. It will eventually turn green, though I won’t spend any time fertilizing it. Weeds look as good as grass when mown. However, if you are someone who likes a grassy green lawn, you may be buying fertilizer soon. I have one request: read the instructions on the side of the fertilizer bag and then follow them. By doing that, you could keep dangerous algae blooms out of our favorite places to canoe, fish, and swim.
A couple months ago, I wrote a column about road salt and the harmful effects that road salt has on our wells and waterways. Road salt contains chloride and sodium. Too much chloride in a lake is toxic for aquatic life. Too much sodium in your well is bad for your health. There are parallels between road salt and fertilizer.
Fertilizer contains nutrients, usually nitrogen or phosphorous. We usually think of nutrients as good, but too many nutrients are bad. Nitrogen can leach deep into the ground and contaminate groundwater. Too much nitrogen in your water is unhealthy. Phosphorous, the nutrient that worries me most, gets washed into streams and storm drains and can ultimately reach a lake or pond. Too much phosphorus in our swimming and fishing holes starts a dangerous cycle. First, the excess phosphorous can cause blooms of algae. Second, the algae indirectly use up the oxygen that aquatic animals need to survive. Finally, the aquatic animals die. You may have heard the technical name for this cycle: eutrophication. Additionally, a certain type of algae bloom, blue-green algae, produces cyanobacteria that is toxic to humans. Some studies suggest a link between cyanobacteria and neurodegenerative diseases such as ALS (Lou Gehrig’s disease). Scientists with Dartmouth-Hitchcock Medical Center have been looking into a possible link between an ALS cluster in Enfield and algae blooms in Mascoma Lake.
When we scatter fertilizer on our yards and gardens, rain washes much of it into the streams and storm drains near our homes. Those streams and storm drains are connected to rivers and lakes miles away or in the next town. That next rainstorm will wash your yard and the road clean of that fertilizer and send it on its way toward the local beach. None of us can escape the fact that we each live in some waterbody’s watershed.
Last year, the New Hampshire legislature passed a law that limits the amount of nitrogen and phosphorous that fertilizers sold in New Hampshire may contain. The law also requires certain information on packaging labels. The law was passed as part of a regional effort to make fertilizer practices consistent among New England states.
You do not need to stop using fertilizer (though I wouldn’t mind if you did). Instead, you can use fertilizer in a smart way so that you get the desired results while also ensuring that it does not pollute a local waterbody. Before using fertilizer, you might test your soil’s pH level with a test kit from stores like Agway. If the pH of your soil is too high or too low, the fertilizer probably won’t work regardless of how much you apply. What a waste of your time, labor, and money! Testing your soil will also help you select the right fertilizer for your soil and help to figure out how much to apply.
If you do use fertilizer, don’t apply it to frozen or bare ground, during the summer dry period, or before or after heavy-rain events. Fertilize in the late spring, early summer, and early fall. If you have waterfront property, don’t use it at all. By law, you are generally prohibited from using fertilizer within 25 feet of the water, and you may only use slow-release fertilizer between 25 and 50 feet from the water.
We all like to swim and fish at places like Nubanusit Lake, Thorndike Pond, and Cunningham Pond. Using fertilizer wisely will help ensure that these places remain beautiful and safe. Some lakes, including parts of Lake Monomonac in Rindge, have had blooms of blue-green algae in the past. We do not have to become resigned to these blooms as inevitable or the new normal. These dangerous blooms are only inevitable if we don’t think about our fertilizer use. Compared to many of the difficult problems we face, this should be an easy one to solve. If you still aren’t convinced, just remember that too much fertilizer is bad for your lawn and plants. That should be reason enough to pay attention