Reducing landscape waste

by
Douglas McEwen
and
Marvin Wolf

In the past, landscape waste such as grass clippings, leaves and brush constituted some 15 percent of all annual materials entering landfills. Now with the State of Illinois act banning the landfilling of landscape waste, homeowners and public agencies are faced with finding alternative means for disposing landscape waste. The challenge for Illinois park districts is more than conforming with the new state law. The real challenge is to show the public how to recycle landscape waste through park management practices, demonstrations and recycling education programs

Grass
Except for some specialized areas like golf course greens, there is no need to collect grass clippings. Park districts need to help change the erroneous, long-held belief that grass clippings cause thatch build-up. This is not true according to lawn experts. It has been found that thatch is not made up of clippings but of roots, leaf sheaths and rhizomes. Grass clippings rapidly decompose in the lawn because they contain very little lignin, the component that resist decomposition. Roots and rhizomes contain higher levels of lignin and are more resistant to decomposition, and therefore, contribute more to development of thatch.

Park districts may also promote the benefits of leaving grass clippings. Grass clippings reduce water evaporation from the lawn. They reduce lawn wear by creating a cushion layer. Finally, grass clippings facilitate better growth by providing nutrients and keeping the soil temperature cooler. One study found that the annual quantity of nutrients produced in clippings from 1,000 square feet of Kentucky Bluegrass range from between 1 and 5.7 pounds of nitrogen, .1 to .6 pounds of phosphorus and .7 to 2.4 pounds of potassium.

Not collecting grass clippings also results in savings in mowing time and expenses. A study of highly fertilized Kentucky Bluegrass indicated that 529 pounds of clippings are produced in 100 square feet each year. If clippings were collected, work stoppage would occur 22 times to empty a basket that accommodates 25 pounds of clippings.

If grass clippings must be collected, they can be spread as mulch around trees, shrubs or in flower beds. Mulch can be created from shredded grass clippings and leaves. Mulching modifies soil temperature and moisture content as well as reducing soil erosion and weed problems.

Compost
As recycling gains in popularity, it is important to remember that as park districts help recycle waste such as aluminum cans, paper and glass, they should encourage the public to think about another recycling option — composting.

Composting is a naturally occurring process that breaks down leaves, grass and kitchen vegetable scraps into humus. In a compost pile raw plant material is broken down through the action of microorganisms. As the material gradually decomposes the center of the pile heats up. This kills some of the weeds, seeds, insect eggs, and disease organisms that are present in the plant material. The finished humus is soft, loose, and smells somewhat like freshly plowed soil.

Anything growing in the yard and kitchen vegetable scraps are potential food for the microorganisms in a compost pile. These tiny decomposers use carbon in the plant material as an energy source. Nitrogen provides the microbes with the raw element of protein to build their bodies. Every plant part has a ratio of carbon to nitrogen in its tissues. A carbon-to-nitrogen ration of 30:1 is ideal for the activity of compost microbe. This balance can be achieved by mixing two parts of grass clippings with one part of fallen leaves.

Humus (compost) is not a total substitute for fertilizer since it will not supply all the nutrients required for optimal plant growth. However, humus will make a soil more porous improving soil aeration and drainage. Since no studies of cost effectiveness have been conducted on composting, park districts would be advised to begin their compost operation on a pilot basis. In any case, these operations can be used for community recycling education programs.

About the Authors
Douglas McEwen is a professor in the Department of Recreation at Southern Illinois University, Carbondale. Marvin Wolf is Superintendent of Parks at Addison Park District.