Earlier this week I sent out an e mail requesting feedback on a proposal to mandate home composting of leaves. Could save the town a few hundred thousand dollars a year--maybe more! The response I received from most people ---they did not like the idea of mandating home composting. As a result of the feedback I have received I think the next step should be to educate and encourage people to voluntarily compost. If you would like to learn more about home composting and help us prove the benefits of home composting, please e mail me at firstname.lastname@example.org
. The following was prepared by Mark Gilliland.
There are two basic methods to talk about based upon this email. One deals with the practice of composting, the other deals with the practice of mulching.
Composting is a slow process in that it can take months for leaves to decompose. The larger the pile, typically, the faster the center decomposes (although there may be leaves which simply take forever to decompose...) Slow decomposition could be an indication of anaerobic conditions (not enough oxygen). To solve this, the pile needs to be periodically turned and aerated. Another factor which slows down decomposition is an imbalanced mix of green (grass clippings, plant cuttings) and brown (fall leaves, newspaper, straw) - the green adds nitrogen (food, nutrients) for use by the microorganisms in the pile. Piles should be a least 4'x4'x4' to achieve enough heat in the center to really get active. Also, compost piles often need a "starter culture" (microbial inoculation) to get really active.
This and more composting "trouble shooting" info is available through Cornell Cooperative Extension.
However, composting really can only be done at a certain limited scale in a homeowner's back yard. Imagine a yard with a 3 bin composter. This would hold around 192 cubic feet of leaves (say 200). Even if compressed a bit, this is still a limited volume. Its equivalent to 768 square feet of leaves 3" deep - or an area 20'x40' at 3" deep. Needless to say, many yards have more sq footage and more leaves annually than this.
This is where mulching comes in handy - a mulching mower or a leaf shredder can reduce leaf volume up to 10:1 (typically around 8:1). That is done mainly by making much smaller pieces which compact together closer and thus take less volume but provide more surface area and capillary space (for oxygen and water). This is why mulched (shredded) leaves will compost MUCH MUCH faster if paced into a compost pile. Also why shredded leaves make such a useful and healthy garden bed mulch.
One other note: the organic materials in leaves do not need to be released as CO2 gas to be effectively decomposed. Rather, much of the material stays in the organic form of humus (a rich textured soil with nutrients, air, water - and in the case of composted humus, full of beneficial bacterial and symbiotic fungus). Thus composting and mulching in place help feed and build soil quality.
In most cases, the yearly "build up" of soil created by adding leaf mulch or compost to landscape beds - or top dressing of lawns with 2" fine compost - will not be significant. This practice has been use by gardeners and landscapers for years and years to help "refresh" the soil nutrients and fix the tilthe (texture, air & water holding qualities).