While the practice of composting has been around for at least a couple thousand years, it has been since the mid 1900’s that much of our scientific knowledge of the composting process has been figured out.
Away from science, you have to look no further than at the ground of any undisturbed forest around here. The fallen leaves, pine needles, branches and other organic material decomposes without the guidelines you read. It will take longer, several months longer, but the process will occur naturally.
The nursery industry and many home gardeners want compost in several weeks to a few months. To have that quick a product, composting processes can be followed to have the correct carbon to nitrogen ratio and the proper amount of moisture. Below, I will skip the details of the science and provide more of a fundamental approach for those new to the concept.
We can simplify the composting process greatly by breaking the ingredients into two parts. We’ll talk in terms of “green” and “brown” materials that you put into a compost pile.
Greens are the nitrogen source. Green materials are colorful, freshly cut and contain moisture. They provide nutrients and moisture for the compost workforce. Your vegetable kitchen scraps, fresh lawn clippings, the pile of weeds you just pulled out of your garden, or other fresh trimmings from your landscape are “greens”.
Browns are the carbon source. Browns provide energy and are also used for absorbing excess moisture and giving structural strength to your pile. Browns would be the leaves that are just now beginning to fall. Pine needles that you gather or old dried out clippings would be a brown ingredient.
At the very simplest, mix 1-part green materials to 2-3 parts brown materials. With lots of leaves (brown material) coming available soon, some gardeners use what they need for the current amount of greens they have and set the remainder of the leaves aside to mix with fresh green trimmings or kitchen vegetable scraps as the greens become available.
You will layer these greens and browns together in an area that is no smaller that 3 ft wide and 3 ft deep. Put a layer of browns first, then alternate greens and browns until you have a pile that is no shorter than 3 ft high.
Volume is crucial to home composters. When constructing yours, make it no smaller than 3 ft wide by 3 ft deep by 3 ft tall. This volume will ensure that you can have enough heat to kill off weed seeds and sterilize diseased plant tissue or other harmful pathogens.
The real workhorse that you don’t even have to add is bacteria and fungi. These are the aerobic bacteria that will create heat as they oxidize the carbon materials present. There are certain types of aerobic bacteria that can heat up the compost pile to as high as 150 F! Numerous gardeners have seen their own piles so warm that it generates steam as it goes about its work.
If you do want to add bacteria or fungus, I wouldn’t recommend purchasing those products. The microorganisms they are selling are already present on the leaves, food scraps and other material you are adding to the pile. If you want to add an inoculant, activator or other additive, simply sprinkle in a shovel full of your best soil and you will have more than enough microorganisms.
It is an interesting process. Not all compost piles reach a very high temperature, so do not be discouraged if yours does not. Be sure to turn your pile every week or two. Under the best conditions, you’ll have useable compost in a month or two, while a pile of unmanaged leaves will take a year or more.
