Behind every scientific equation in composting lies an art form that’s different for everyone. Composting isn’t necessarily a hard thing to do; other than the materials, equipment, waste and space, all it truly needs on your end is patience and commitment. We’re not exactly painting the ceiling of the Sistine Chapel, but we’re going to make a healthy, sustainable garden fit for one with just composting alone! Remember, it’s a trial and error method until you find the perfect scientific solution to make your ideal batch of compost.
Let’s begin with an explanation of the carbon/nitrogen ratio, or the C/N ratio. In order for you to have a successful, usable batch of compost you have to have the right balance between the brown stuff and the green stuff. Get your mind out of the gutter! It’s not what you really think it is! The brown stuff, like dried leaves, tree bark, straw and hay have a lot of carbon, and the green stuff like fresh grass clippings, fresh leaves, chicken manure, fruit wastes and food scraps have a lot of nitrogen. This is where the simple scientific equations come in; actually it might be better if you think of it more as a cooking recipe because it really is!
According to Home Composting Made Easy, it’s best if you try to achieve the ideal 30:1 C/N ratio for your compost. This average ratio basically describes the chemical composition of your materials, NOT 30 times the amount of brown stuff to one of the green. With this ratio you’re bound to reach a hot temperature of about 140 degrees Fahrenheit, which is ideal for the microbes in your compost to eat up all the carbon and nitrogen rich goodies.
Another recipe that you can follow is the “2 parts green, 1 part brown” recipe also found in Home Composting Made Easy. This basically means that you can achieve the 30:1 to 50:1 ratio, the latter being ideal for low temperature compost batches, by including two parts of green stuff to one part brown stuff. For example, if you mix grass clippings (17:1), non-diseased and seedy weeds (20:1) with dried leaves (60:1) and divide that up by three, you have a product of 32:1, which is close to the 30:1 average. Of course, you should play around with your recipe to find the perfect fit for your batches. As long as you don’t have too much green or too much brown, you should have a successful batch of ready to use compost!
Remember, composting is a science and an art form. Keep working at it and use these basics to find the perfect C/N ratio.
*Referenced from Home Composting Made Easy by C. Forrest McDowell, PhD and Tricia Clark-McDowell, 2002.