Study Shows Fertilizer May be Ineffective in Salt Marshes

Add fertilizer to your garden and your plants will probably grow bigger and taller. Add fertilizer to a salt marsh and the plants may not get any bigger at all. That's according to a new study led by Dr. David Samuel Johnson of William & Mary's Virginia Institute of Marine Science.

The study results have important implications for the management and care of salt marsh habitats. These coastal resources have long thought to be "nutrient sponges" that soak up excess nitrogen through greater plant growth and other means, thus helping to prevent low-oxygen dead zones, fish kills, and harmful algal blooms in nearby waters. Lack of enhanced plant growth in the current study throws this assumption into doubt.

Says Johnson, "Our work underscores that we can't simply rely on salt marshes to clean up nutrient pollution. We need to do better job at keeping nutrients out of the water in the first place." Sources of excess nutrients include wastewater and runoff of agricultural and lawn fertilizers. Their presence in coastal waters can lead to over-fertilization or what scientists call "eutrophication."

https://phys.org/news/2016-11-salt-marshes-limited-ability-absorb.html

Jack Flanagan

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