With these principles in mind, everyone can make compost.
The compost pile is really a teeming microbial farm. Bacteria, the most numerous and effective composters, are the first to break down plant tissue. Fungi and protozoans soon join the bacteria and, somewhat later in the cycle, centipedes, millipedes, beetles and earthworms all do their parts.
Anything growing in your yard is potential food for these tiny decomposers. Microorganisms use the CARBON in leaves or woodier wastes as an energy source. NITROGEN from grass or green materials provides the microbes with the raw element of proteins needed to build their bodies and multiply. (The more decomposers there are, the faster the compost pile will break down.)
Materials with a higher carbon content include "brown" materials like dried leaves, dried weeds, straw, sawdust, wood chips, or sticks/branches. Materials that have a high nitrogen content include "green" items like fresh grass clippings, green weeds, cow or horse manures, and fruit and vegetable trimmings from the kitchen.
What's the "best" recipe for compost? It depends! But a good rule of thumb is to build a pile that has about 50% green materials and 50% brown materials.
The more surface area the microorganisms have to work on, the faster the materials will decompose. Chopping, shredding, or chipping garden wastes before adding them to your compost pile will help speed up the decomposition process.
MOISTURE AND AIR
All living things on Earth, including the microbes in a compost pile, need a certain amount of water and air to sustain themselves. Microbes function best-and composting happens the fastest-when the compost heap is about as moist as a wrung out sponge. It is usually necessary to add water to the compost pile to keep the decomposition process going. The pile also needs to be turned periodically to get more air into the center of the pile.
A large compost pile will insulate itself and hold the heat given off by decomposers. The pile's center will be warmer than its edges. The ideal compost pile size is 3' x 3' x 3' (one cubic yard). Piles smaller than this will have trouble holding this heat, while piles larger than 5 feet on a side don't allow enough air to reach the decomposers (microbes) at the center.
Note: These proportions are only important if your goal is to make compost quickly. Slower composting requires no exact proportions.