For cleaner waters, less algae, eliminating fish kills
What’s good for lawns near wetlands is good for all of Arlington’s lawns.
With a modification to the wetland permit conditions for properties having wetlands or waterways, the town’s Conservation Commission took a significant step to cleaning town waters. That includes groundwater, Spy Pond and the Mystic River.
The step? By reducing nitrogen pollution from lawns within the commission’s jurisdiction that have been permitted for work since last August.
The solution is to stop applying pounds of quick-release fertilizer and instead, if needed, to apply one-half pound slow-release fertilizer in either spring or fall.
Leaving the grass trimmings on the lawn is the equivalent of giving a lawn one pound of fertilizer a year. Many established lawns do not require annual fertilizing.
Ocean River Institute role
Rob Moir, executive director of the Ocean River Institute, in Cambridge, recommended lawn-care modifications to the commissioners.
He spoke about a fish kill in Arlington’s watershed last summer, when many striped bass in Boston Harbor chased thousands of menhaden into the Mystic River. The fish raced into an ocean dead zone and the dark-muscled fast-swimming fish died quickly off Everett’s shore. This harmful algal bloom had consumed all of the oxygen in the water.
It happened during summer with many hours of daylight, and the surface waters were a bit warmer than previous summers. In those conducive conditions, the limiting factor to whether or not algae bloom (grow and die rapidly) is nutrients. In salt water ecosystems, such as the Mystic below the Amelia Earhart Dam in Somerville, the limiting nutrient is nitrogen; in fresh water, it is phosphorus.
In 2012, Falmouth experienced a fish kill when 12 striped bass and one horseshoe crab were found dead on the shore of Little Pond, a salt pond next to Nantucket Sound. The residents blamed nitrogen from the lawns that stretched down to the water’s edge.
Falmouth passed a bylaw prohibiting the use quick-release fertilizer, the industry calls for one pound applied five times a year or five pounds annually. Instead, residents were to spread no more than a half pound of slow-release in fall or spring, but not summer. Since residents stopped spending money on fertilizer, there have been no more fish kills.
Mystic Watershed conditions
In the Mystic River Watershed, conditions are different, the waters are colder and not as enclosed as in a Falmouth salt pond. The three sources of nitrogen are septic/sewage, agriculture and fertilizer. By the Mystic, septic and sewage is treated by the MWRA. Agriculture makes up a smaller percentage of water frontage, and agriculture is being watched by vigilant conservation commissioners. This leaves nitrogen pollution from lawns a greater factor for causing harmful algal blooms.
Moir said the advantages of slow-release fertilizer are similar to those of feeding children a high-protein breakfast instead of a sugary one. Children with the high-protein , slow-release diet will make it to lunch running full bore.
Moir explained that slow-release fertilizer feeds grass over the time. Quick-release will wash off or percolate through away from the grass with the first rainfall. There is little uptake and much nitrogen pollution, he said.
Slow-release fertilizer consists of spherical granules of varying sizes. Each granule of nitrogen is coated with a unique vitamin packed resin that controls the release of the nutrients. The resin is water soluble over time. No water, no nutrient release.
Thus, slow-release spread in October will be available to plants when spring rains return. The coating mixture is formulated to feed beneficial microbes in the soil which sustain healthier grass plants.
Slow-release fertilizer, sparingly spread, results in grass roots that go deeper, because the plants are not swimming in quick-release. Grass and soils are healthier; grass is more resilient, and will grow more foliage. Naturally, the lawn becomes more resistant to pests and weeds.
An established lawn that is only fertilized with one half pound of slow-release will capture more carbon allowing the grass to be a better sponge. More absorbent grass buffers your home from extreme weather events that are occurring with increasing frequency. Replacing patio and hard surfaces with this lawn, you may fight climate change from the comfort of a lawn chair in the company of robins.
This news summary was published Wednesday, May 29, 2019.
