There are a number of factors involved in the decomposition of organic matter:
Composting is basically the science of growing microorganisms that activate the decomposition process. Since all bacteria need a mixture of carbon and nitrogen to survive, these elements play a vital role in keeping the bacteria happy and thriving in the compost pile!
This is an important factor. This ratio determines how easily bacteria can decompose organic
material. In the compost pile microorganisms use carbon for energy and nitrogen for protein synthesis.
We can break things into two groups, the "greens" and the "browns". Greens are materials high in nitrogen content, such as food scraps, grass clippings and rotted manure. Browns are carbon-rich substances like wood products, leaves, straw, paper, and corn stalks. The optimum proportion of greens to browns is 30 parts carbon to 1 part nitrogen. Measured in equal units--piles, bags, bales, etc.--materials can be combined to achieve the ideal ratio for fast and efficient decomposition. A pile made up of one-half fresh grass clippings and one-half dried leaves [wet!] is close to the perfect 30:1 carbon/nitrogen ratio we seek. Different materials of course require different combinations. This chart sketches the basics of the C:N ratio.
| Food scraps | 15:1 | GREENS |
| Grass clippings | 19:1 | |
| Rotted manure | 25:1 | |
| IDEAL RATIO | 30:1 | |
| Corn stalks | 60:1 | BROWNS |
| Leaves | 40-80:1 | |
| Straw | 80:1 | |
| Paper | 170:1 | |
| Sawdust, wood chip | 500:1 |