Creating a compost pile as a classroom project will demonstrate to students that natural materials can be recycled.
A location for the project, organic waste materials, a garden pitchfork, soil, water. (Lime, manure, nitrogenous fertilizer, materials to construct an enclosure, a ½inch mesh screen, and a soil thermometer are optional.) Volunteers must be available to construct and maintain the compost pile.
Compost is an inexpensive and effective soil conditioner that recycles organic waste materials. Nutrients in plant material are returned to the soil through the breakdown of organic material by the action of microscopic fungi and aerobic bacteria. Organic wastes are decomposed, and the result is a material useful as a natural fertilizer.
In Japan, Europe, and recently in the United States, municipalities have established large-scale solid municipal composting facilities. The volume of organic material composted is diverted from other disposal facilities. Municipalities have found that composting leaves collected in the fall can save disposal fees.
When properly managed, a compost pile will not produce odors or attract pests. The finished product can be ready for use as a garden mulch in as little as six weeks with proper management. Compost has proven valuable for use in land reclamation efforts where erosion or earth moving activities have disturbed the topsoil.
1. Find a suitable outdoor site to locate the compost pile. The pile should be exposed to rainfall, but may work best in a shaded location. Proximity to a water source is suggested.
A good time to start a compost pile is whenever organic materials are available. The fall of the year is quite suitable, since composting can serve as an alternative to the burning or landfilling of leaves. Tree-trimmings, grass clippings, garden refuse, kitchen and lunchroom food wastes, sawdust, manure, wood ashes, hay and straw are among the organic wastes suitable for composting. Meat and dairy products should be avoided.
2. Develop a plan of operation that outlines the procedures for conducting the composting project. Present the plan to the school principal. Permission and support from administrative and maintenance personnel must be obtained before initiation of the composting project.
3. An easy to manage compost pile can be enclosed on three sides by utilizing wooden pallets, used concrete block, fencing, snow-fencing, or hay bales. The fourth side should be accessible to permit turning the pile. A 4'x4'x4' enclosure can yield a ton of compost.
A compost pile can be constructed without an enclosure. A shallow pit may be excavated and the organic material simply piled. The excavated soil will be added to the pile.
4. Begin the compost pile with a layer of branches or cornstalks to help promote ventilation and drainage. The compost pile is then built with successive eight-inch layers consisting of a six-inch layer of organic material moistened with water and covered with two inches of soil, lime, manure or nitrogenous fertilizer. Shredding the organic materials will accelerate the decomposition process.
The eight-inch layers are repeated until the pile is four feet high. Each layer should be moistened, but not soaked. Materials in the compost pile should always remain as damp as a squeezed sponge. A depression created at the top center of the pile will collect precipitation. (Layering of materials is not essential to the process.)
5. The compost pile is now ready for decomposition. During this phase the temperature within the pile may reach 175 o F. The heat is effective in eliminating most disease organisms, insects, and weed seeds. Diseased or infested materials should not be added to the compost pile.
The pile should be turned over and mixed every few weeks to move outer materials to the center. Less frequent turning will delay decomposition. A steady decrease in the temperature at the center of the pile will signal the end of the fermentation process. When the compost is finished, it will have a dark color and a crumbly soil-like texture.
6. Maintain a record of the composting process. Enter the date of compost pile construction, the organic materials added to the pile, the days the compost pile is turned, the date the compost is ready, how the compost is used and other observations.
7. A soil thermometer can be used to monitor the temperature of the pile. Create a compost pile temperature chart plotting thermometer readings over the term of the project.
8. The finished compost may be sifted through a ½" mesh screen with rejected particles returned to the compost pile, or the compost may be added directly to garden soil. Applied as a mulch or top dressing around plants shrubs and trees, the compost will provide soil nutrients, retain moisture, and inhibit weed growth. Look for uses for compost around the school grounds. Consider marketing sifted compost as a fund-raising activity.
9. Prepare a report that will describe the composting project. Refer to the project log (Item 6) for key information. Present the report to the school principal. Consider publicizing the project in the school and community newspaper.
This lesson plan was prepared by the Recycling Division of the Pennsylvania Department of Environmental Protection.