Amanda McNulty: Leave those leaves off the curb

11/04/2010 12:00 AM

11/15/2011 11:34 AM

My teenagers have been marking storm drains with warning stickers through a Clemson project and now tell me not to put my leaves on the curb side; that it can harm the river system. I’ve been recycling for years, drive a hybrid, and now these kids say I’m polluting. What’s the deal?

It sounds like they’ve been volunteering for Carolina Clear, a Clemson program that addresses water quality education, and they got an “A.” Those piles of leaves were once filled with chlorophyll, that remarkable molecule that fuels life on earth through photosynthesis. In the presence of sunlight (plants are the original users of solar power), that molecule turns water and carbon dioxide into sugar and directly or indirectly feed all life on earth.

The major nutrients plants get from the soil are nitrogen, phosphorus and potassium, and their leaves are made of these substances, too. Leaves have openings in their underside called stoma that act like windows to let in air when plants are actively photosynthesizing. The chloroplasts (cells that contain chlorophyll) extract the carbon dioxide they need and, in return, release life-giving oxygen as a by-product.

When deciduous trees lose their leaves in the fall (or evergreens recycle their leaves periodically), those tissues still contain many valuable nutrients. Leaf mulch is a great source of compost as it slowly adds organic material and minerals back to the soil. But when put on the curbside, those leaves either are buried deep in the ground or get washed into a storm drain.

From there, they end up in streams, lakes, or rivers and start to decay, releasing the nutrients all plants need to live. Colonies of algae floating in those places don’t have roots – they can only get required minerals from the water, and those dissolving leaves act like Ensure.

Whamo -- the algae happily reproduce like crazy. In the daytime, they release oxygen during photosynthesis, but at night they use it during respiration. The worst problem, however, comes when they have consumed all the food from your wayward leaves (or grass clippings) and die. Then tiny, oxygen-breathing organisms eat the dead algae and the dissolved oxygen levels plummet. Those poor fish, happily minding their own business, and completely dependent on oxygen dissolved in the water to breath, are suffocated. All because you put those leaves on the curb!!!

Actually, it isn’t ever the action of just one person. Non-point source pollution has so many offenders that we could never identify every bad guy. But gardeners and lawn lovers can be tremendously helpful in combating it.

Never throw away organic matter – it’s like gold when added to your soil and doesn’t require any fancy composting devices. A spot behind the garage where you pile up grass clippings, kitchen scraps, and, yes, those leaves, will quickly reduce in size (oh, to be a compost pile). If you cut your grass correctly, those clippings are best left on the lawn which will happily accept the nitrogen they contain.

It will rain again one day so resolve now to leave the curb clean. Take a few moments to search Clemson Carolina Clear and Clemson Home and Garden Information Center to learn how to protect our water supply and how to compost at a speed that matches your temperament.

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