The process of composting is basically that of farming micro and macro organisms. Keep them happy and they will do the job of turning your yard scraps into compost.

One of the key ways to promote a healthy population of these decaying critters it to be sure they have a good food supply. Like all living things, they need certain basic elements to build proteins and sugars in order to grow and reproduce. For composters, this means a proper supply of nitrogen and carbon.

Not only do the decaying organisms we want to encourage need nitrogen and carbon, they need them in a certain ration to thrive. The ideal ration appears to be around 20 to 25 parts of carbon and 1 part nitrogen.

Generally speaking, carbon items are those plant parts that are brown while nitrogen is represented by those that are still green when added to the compost bin. Of course, nitrogen can also be added by adding small amounts of regular garden fertilizer to the pile.

The following tables give an idea of the relative carbon to nitrogen ration of some common plant based matter that can be used in a compost pile:

That ratio is a nice number but how in the heck to we achieve it in our backyard compost bin? Do we weigh everything we add in terms of brown and green? That would be a very time consuming process for most of us.

Actually, keeping the right balance of nitrogen and carbon is part of the "Art" of composting. It really boils down to your observing the pile and making adjustments as necessary. But, how do you do that?

Generally, if the pile has a good C:N ratio, it will be warm with a temperature at least in the 80 to 90 degree F. range. There will be no disagreeable odors to the pile either.

So, here are some guidelines for when to make adjustments to the carbon or nitrogen side of the equation:

• Pile has Odors - A noticeable odor, especially of ammonia, is an indication that too much nitrogen (green) is present. This is a time to add a high carbon material such as sawdust, brown leaves, etc.
   

• Pile has No Heat - This is a sign that the microorganisms are not working very yard. Often this calls for addition of more nitrogen and, perhaps, moisture.

Composting Site Selection Criteria

• Intro to Composting
• Types of Composting
• Organisms
• Carbon:Nitrogen Ratio
• Site Selection
• Composting Bins
• Equipment
• Starting the Pile

• Maintaining the Pile
• Aeration
• Watering
• Finished Compost
• Using Compost
• Troubleshooting Problems
• Composting Terminology

Note: We have provided some general information and observations on this topic aimed at the home gardener. Before you take any serious action in your landscape, check with your state's land grant university's Cooperative Extension Service for the most current, appropriate, localized recommendations.