Thursday, August 16, 2012

Compost May Not Be Good for Florida's Aquatic Systems

Composting can provide many benefits for Floridans. Composting recycles nutrients sequestered by plants back into fertilizer-like substances. Plants then utilize composted organic matter to grow.

Composting though, must take place in the right place and right manner. Open raw compost may create serious health issues.

When we design Urban Green systems, including stormwater shelves and bioswales, we try to specify plants that contribute a minimum of leaf litter to the waterways. Deciduous plants, even if they are native species or important food plants may contribute too much biomass in the form of leaf drop (litter). Though there is a time and place for nitrogen and phosphorous rich compost, the excess biomass may not belong in community ditches, open lots or out in the open. Instead, proper composting may require proven permaculture approaches.

Though we desperately need to create urban habitat for wildlife, we must also create habitat in a responsbile manner. Whereas food chain effects and predators control nuisance wildlife populations such as rodents, squirrels and raccoons, these critters can cause serious health and safety issues in the Urban Core if attracted by improperly treated compost. Racoons in particular are significant carriers of roundworms and other parasites. Very recently, someone we knew well was hospitalized at Shands in Gainesville for life-threatening roundworm issues attributed to racoons around their house. Epidemiology studies show racoons to be a serious health issue in some locals and carry parasitic creature eggs that can infiltrate even the cleanest of houses on the bottom of sandals or shoes.

Properly composted organic matter may potentially be used in a safe manner in Florida permaculture gardens, yet as with all fertilizers, compost should be used in a specific application, one directed at food or landscape garden growing. Keeping nutrients where they are needed and out of Florida's water systems is an important and oft-overlooked component of good permaculture science.

By keeping additional nutrient rich organic and composted plant matter out of the aquifer, our creeksand rivers and other waterbodies we also limit potential for suffocating algal growth.

Algae, like any other plant relies on nitrogen and phosphorous to grow. The more nitrogen and phosphorous in water, the more algae in the waterbody.

While there is nothing inherently wrong with algae, like any other living organism uncontrolled algal growth can choke out all other forms of life, stealing all available oxygen from the water and blocking light neccessary for photosynthesis.

Keeping nutrients out of the water that may feed algae is an important reason for keeping compost and dead and decaying plants out of aquatic systems. Simply put, nutrients sequestered out of the water by being taken up through plants should not be allowed to reenter waterways. Once a plant dies and decomposes, most previously sequestered nutrients may be released from the plant matter back into the water. Once back in the water column nutrients feed more algae blooms with potent nitrogen and phosphorous compounds.

Giant bullrush growing in stormwater pond, sequestering nutrients and toxins

The above photo depicts giant bullrush growing in a stormwater facility, taking up and sequestering toxins and nutrients.

Practically speaking, herbicide use in ponds to control weeds never really promotes clean water. In fact once plants die from herbicide application the once sequestered nitrogen and phosphorous leach out of the dead plant material back into the water. What was once removed from the water column is soon released back into the aquatic environment. These nutrients can travel for hundreds of miles dissolved in underground aquifer water to reemerge in a pristine river or lake. Soon algae may be filling our our waterbodies, including those used for recreation and water supply.

Same pond as above, one month later after herbicide application, bullrush composting into the pond, rereleasing toxins and nutrients back into the aquatic system

The above photo depicts giant bullrush sprayed with herbicide, now composting in the pond, soon to release previously sequestered nutrients and toxins back into the water supply.

Though many municipalities today use herbicide applications to keep algae and other plants at bay, the process is self-defeating. As soon as the sprayed algae and aquatic plants such as cattail and reed die and compost where they once grew, all the nitrogen and phosphorous originally sequestered becomes rereleased into the aquatic ecology to fuel more algal growth.

A better solution for removing nutrients and toxins from stormwater facilities is to harvest the plant biomass after cuttinginstead of spraying with herbicide. Removing sequestered nutrients this way is refered to 'nutrients in -nutrients out'. Nutrients and toxins flow into the ponds, plants grab and sequester the nutrients, plants are harvested thus removing nutrients from the waterway systems.

Composting can be a good permaculture practice if done where nuisance wildlife are not attracted into residential areas and thenutrients are not rereleased back into our waterways.

Spraying herbicides to kill algae and other vegetation in ditches and stormwater ponds is composting in an incorrect manner.

Using native evergreen plants and those plants with low leaf litter rates can reduce the necessity to remove vegetation litter and algae.

Harvesting the biomass and composting in a well designed municipal or neighborhood facility can keep nutrients out of Florida's waterways and our waterbodies free from unneccessary algal blooms.


Anonymous said...

I'm confused here. Bullrush is a great plant to have around any stormwater pond, providing food and habitat, and as you say sequestering nitrogen and phosporus. Why would anyone want to intentionally get rid of it? The health problem with too many storm water ponds in Florida is not having any native littoral plants around the perimeter.

Kevin Songer said...

Dear Back Ten Feet: You are correct - getting rid of bullrush makes no sense as does much of our government today. Its up to us to educate our regulators or, if they do not listen, vote them out of office!

Anonymous said...

F you, I bought water front property now comsumed buy bullrush.. not nice to look at. Can't get rid of it even with roundup. HOA won't do anything.Am I f'D????