Science to Support Fertilizer Controls

Dr. Leesa Souto, Executive Director, Marine Resources Council of East Florida, Inc., details why fertilizer controls are essential to healthy waterways.

Read more: Science to Support Fertilizer Controls

Muck

muckThe Indian River Lagoon was once a sandy bottom estuary, with a modest accumulation of organic detritus from shoreline and aquatic vegetation loss.The bottom of the lagoon is now covered in a layer of fine silt and sediment called “muck” that has accumulated over years of excess sedimentation. Silt, sediment, and other fine particles carried in by tributaries, canals, and storm drains accumulate and break down on the bottom, forming thick black ooze. This ooze or “muck” builds up in channels and deep pockets where it has reached depths of up to 15 feet. The muck blocks light from benthic grasses and organisms and it serves as a legacy load that slowly releases nutrients back into the water column.

Florida Inland Navigational District  (FIND)Muck dredging is the most effective way to remove this material. The Florida Inland Navigational District (FIND) is a special taxing district that improves navigational channels and restores spoil islands in the Indian River Lagoon. They have successfully completed extensive muck removal projects in the Sebastian River and Crane Creek, making these tributaries cleaner and more navigable. They have completed the first phase of muck removal in the Eau Gallie River and are working on supporting funds to complete the Eau Gallie River project in the coming year. Muck removal is important to the health of the Indian River Lagoon.

Exotic Invasive Species

lionfishThe Indian River Lagoon is home to more species than any other estuary in North America. Unfortunately, the conditions that make it suitable for so many species also make it vulnerable to invasion by unwanted species that harm the ecosystem. These include aquarium species such as lion fish and caulerpa, a common aquarium plant that outcompete local species, and Brazilian pepper that invade the shoreline and displace native mangrove species.

How Does Your Lawn Hurt the Lagoon?

nitrogen source allocation from residential land use

Local leaders pass residential fertilizer controls to help protect the Indian River Lagoon from nitrogen pollution! Click here to learn more about local fertilizer ordinances.

Nitrogen and phosphorous from lawn fertilizer accumulates in soils and grass clippings, it runs off during rain events, and it leaches through the sand and into groundwater that leads to the lagoon.

Fertilizer may be the largest contributor of nitrogen to the Indian River Lagoon. Nitrogen load calculations based on typical residential fertilizer application amounts, average septic tank nitrogen releases and atmospheric deposition shows that fertilizer contributes more than three time more nitrogen to the watershed than septic tanks.

Many people purchase lawn fertilizer and apply it themselves or they hire a professional company. There are differences in the fertilizer products, that vary according to the content of nutrients (N–Nitrogen, P–Phosphorous, and K–Potassium) and the slow-release capability.

reading the fertilizer bag labelMartin County has a good explanation of how to read a fertilizer bag label in their fertilizer brochure.

The slower-release the product, the more likely it will contribute to the growth of organics in the soil that can sustain the lawn in the long-run. In sandy soils, liquid fertilizers don’t stay around long enough to encourage microbial activity. Whatever isn’t immediately taken up by the grass, simply passes through the sand into the groundwater.

Lawn Grass Clippings

The fertilizer that is taken up by the grass is stored until the grass is cut. Many grass clippings full of the chemical fertilizer will end up in the street or in the canals where they break down and release the nitrogen load directly back into the lagoon before they settle on the bottom to contribute to the legacy load of accumulated muck.

keeping grass off the streets

  • Keep lawn clippings on the lawn
  • Mow so that the chute directs the clippings away from the street and driveway
  • Blow lawn clippings off the street and driveway back to the lawn
  • Use a self-mulching mower
  • Remind your professional mower to keep lawn clippings out of the street!

What Are the Issues?

There are many issues affecting the Indian River Lagoon.

The Homeowners Guide to the Indian River Lagoon by the Indian River Lagoon National Estuary Program provides a good overview of the most pressing issues impacting the Indian River Lagoon. But the most damaging pollutant that is impacting the Indian River Lagoon and all of the estuaries of the world is excess nitrogen.

Issue #1: Nitrogen

How nitrogen harms the estuaryHow nitrogen harms the estuary

Nitrogen accumulates in our water bodies causing excessive algal growth of both normally occurring and unusual algae. The buffering capacity of the system depends on normal bacteria and algal activity. When the system is stressed, its buffering ability fails and excessive numbers of algal species occur with catastrophic results. The cloudier the water gets, with excess algae, the more harmful it is to the ecology of the system, which is dependent on sea grass as its primary production mechanism.

Read more about how the lawn can harm the lagoon.

Issue #2: Exotic Invasive Species

The Indian River Lagoon is home to more species than any other estuary in North America. Unfortunately, the conditions that make it suitable for so many species also make it vulnerable to invasion by unwanted species that harm the ecosystem.

Read more about how exotic invasive species harm the estuary.

Issue #3: Muck

The Indian River Lagoon was once a sandy bottom estuary, with a modest accumulation of organic detritus from shoreline and aquatic vegetation loss.The bottom of the lagoon is now covered in a layer of fine silt and sediment called “muck” that has accumulated over years of excess sedimentation.

Read more about how muck harms the estuary.