Composting
Composting refers to the process of combining organic materials such as weeds, grass clippings, and food scraps under conditions that enhance the rate at which they decompose. In the United States, organic wastes make up 20% to 40% of what we throw away. Composting provides an opportunity to keep these organic materials out of landfills and incinerators, using them instead to create a useful end product.

Of course, composting isn't as easy as simply throwing organic waste into big piles and waiting for it to decompose. If moist food scraps or grass clippings are placed in a container and left to sit for a week or two, the result is likely to be a stinky mess that attracts flies. Given the proper conditions, these same organic materials can be composted to produce a material that looks and smells like rich soil and is prized by gardeners. Clearly the second option is preferable, and the key question is how to provide the proper conditions for problem-free composting. The answer lies in paying attention to moisture content, airflow, and the mixture between materials that are high in carbon and those that are high in nitrogen. Investigation of these factors offers many possibilities for student research focusing on the biology, chemistry, and physics of composting.

Composting takes place at a wide range of scales, from huge commercial or municipal operations to simple backyard bins or heaps. It can also be carried out indoors in containers such as garbage can bioreactors or worm bins. For research purposes, composting can even take place in soda bottle bioreactors, which are small and inexpensive enough to enable students to build their own individualized systems. Once made, compost can be used for gardening projects or for plant growth experiments ranging from nutrient analysis of compost-enriched soils to use of composts to suppress plant diseases.

For more information, visit Cornell's Composting in Schools web site or read Composting in the Classroom, an online book providing a comprehensive guide to the science of composting and possibilities for student research projects.

Composting Links

• Virtual compost pile
• Microbe Zoo: Composting
• Cornell's Composting in Schools
• Composting in the Classroom -- a guide to student research