Composting your clippings.

Yard waste is a hot topic these days--thanks in large part to an increasing public emphasis on recycling and the environment. By the end of 1992, 25 states and the District of Columbia had passed, laws regulating the disposition of yard waste. Of these, 17 specifically banned yard waste--grass, tree and shrubbery trimmings, and leaves--from landfills either immediately or at a specific future date.

Law banning yard waste from landfills have already taken effect in both Illinois and Massachusetts, and although Indiana's landfill ban doesn't take effect until September 30, 1994, law goes farther than most by requiring that 35 percent of a community's solid waste stream be recycled by 1996 and 50 percent by 2001. Most other states either have, or are considering, similar legislation.

All of this means that countless communities around the U.S. already are, or soon will be, asking themselves the same questions, namely: If we can't put our yard waste in a landfill, what do we do with it? and How do we meet state-mandated recycling goals?

Yard waste composting facilities offer communities an excellent solution to both of these dilemmas. When yard waste composting sites are planned and managed correctly, it costs less to turn yard waste into compost than it does

to employ other disposal methods.

What does all this have to do with those of us who are involved in parks and recreation? Plenty. Park and recreation districts are usually one of the major contributors to a community's total yard waste volume. They are also one of the prime potential beneficiaries of the end product of yard waste composting, the compost itself. Therefore, it's in the best interests of both the local parks and recreation department and the community to involve its staff in planning and developing a community yard waste composting facility.

Despite the fact that Europeans have successfully composted on a large scale for years, when Americans first began to experiment with large-scale yard waste composting, they often failed. Too many of these first facilities were either poorly managed or used incorrect composting techniques, which created numerous problems. The result was that yard waste composting sites developed a negative reputation in many communities.

Proven Techniques

However, there are ties in the U.S. that are success unobtrusively composting yard waste. These U.S. facilities use proven techniques--many of them borrowed from European facilities--to effectively and economically compost yard waste. The key to establishing a successful composting facility in your community is knowing what technique work and what techniques don't.

Yard waste composting is a relatively simple process. It's also completely natural--the the decomposition that occurs at a yard waste composting facility is exactly the same as the decomposition that occurs on the forest floor. However, large-scale yard-waste composting requires that this decomposition occur quickly, with a minimum of effort, in a relatively small space and without an objectionable odor. These requirements have created problems for some sites.

Most of the problems encountered by yard waste composting facilities fall under two broad categories--one is excessive processing costs, and the other is objectionable odors. To avoid these problems a facility must:

* Minimize the number of times material is moved or handled.

* Use adequate woody and carbonaceous bulking agents such as wood and leaves in its material mix.

* Always employ the best equipment available to properly shred, mix, windrow organic debris and periodically the windrows.

Proper site location, design and preparation are other factors that are critical to the success of a yard waste composting facility. Easy access for trucks entering and leaving the site is a necessity. Although a properly sited and managed composting facility will not produce any objectionable odors, when possible, it's best to locate these sites in a non-residential area. Depending on local zoning ordinances, industrial areas are often the best choice, since they generally meet both criteria.

Here are three primary goals of site design and preparation:

* Keep the distance the material to be composted travels to a minimum.

* Prepare the site properly so that it is passable in any weather.

* Provide fast and convenient procedures for tipping raw materials and picking up finished compost.

Less Cost, Less Odor

There are many different approaches to processing yard waste into composting. We have found that the best way to handle incoming material is to have the trucks that bring the yard waste to the facility dump it right where it is to be windrowed. Then the incoming yard waste is immediately mixed with the proper proportion of bulking agents to help neutralize odor development. Within 48 hours, this material is loaded into the shredder, processed, and ejected into a uniform composting windrow. In more traditional tub grinder operations, incoming material is dumped in a staging area, shredded, loaded into a truck or loader again, and moved to a windrow.

There are several advantages to the former approach--it is more efficient, less costly and produces substantially less odor. The main problem with the traditional method is that every time a pile of composting material is disrupted, odor-producing gases are released--especially during the first 30 days of grass decomposition.

After the yard waste has been windrowed for the proper amount of time, the final step in the composting process is to produce a uniform-textured, high-quality and marketable end product. To do this, the composted yard waste must be run through a screen that separates the rough, uncomposted material such as sticks and trash. Then the finished compost is stored for 30 days to ensure that the final product is fully degraded.

Yard waste composting facilities need to have contingency plans in place to deal with certain key variables that occur during the year. The most important of these variables is volume surges. Different times of year produce different waste types and volumes. A well-planned facility must be prepared to handle these variations.

Spring produces a lot of brown grass (thatch), brush and leftover leaves. This material poses no real problems, since it composts rapidly and leaves no odor. However, in late spring and early summer when lawns are growing quickly, a site will take in mostly grass, and this can lead to odor problems. The grass must immediately be mixed with enough bulking agents such as wood chips and/or leaves to halt odor production.

In the fall, the site will take in more leaves than grass. Although they are easy to compost, some leaves should be stockpiled so they can be used as a bulking agent and carbon source the following year.

A yard waste composting site doesn't simply provide a place to dispose of trimmings. It also produces a high-quality natural soil amendment. Compost increases the ability of soil to retain water, slowly and steadily releases nutrients into the soil, and, through microbial action, restores the soil structure that chemical fertilizers destroy.

The Compost Advantage

Many park and recreation districts and landscapers are discovering that compost offers many advantages over oak bark mulch. Compost retains moisture better than oak bark mulch does, has a better R factor in winter for protecting perennials, and is nutritional, while oak bark mulch isn't.

Compost can also be used by itself as a soil amendment, a top dressing, a replacement for peat moss, a growing medium, an ingredient in specially blended soils and to remediate polluted soil at industrial sites. With all the potential benefits that compost has to offer, park and recreation departments should be in the forefront of those governmental agencies that are encouraging large-scale yard waste composting.