Build Your Own Compost Pile or Bin!

Compost changes soil structure in the very best ways, converting your average garden soil into one that’s friable and fertile.

Finished compost adds nitrogen, phosphorus, and potassium, making soil nutritionally rich. It acts as a pH buffer by bringing the pH to a neutral level (a middle ground between acidic and alkaline). Compost also saves you time and money since it dramatically increases soil’s water-holding capability. Water run-off is reduced, diseases are suppressed, and a healthy wildlife environment is created all thanks to compost.

The best way to get compost into your garden is to make it yourself at home. Lucky for us, the transformation of organic matter into this rich nutrient source is uncomplicated and inexpensive, and it doesn't even smell.

Four Compost-Making Necessities: Carbon, Nitrogen, Water, and Oxygen

You just need four things to create rich compost:

1. Carbon organic material (browns)
2. Nitrogen organic material (greens)
3. Water
4. Oxygen

Although there are many critters in compost piles (such as worms) that help break things down, the bacteria, fungi, and actinomycetes – the microbial decomposers –are the heavy lifters in a compost pile. All organic matter is composed of carbon and nitrogen; they just show up in different percentages. When organic matter is predominately carbon, we refer to it as “brown.” Those that are heavier in nitrogen are “greens.”

In terms of the carbon-to-nitrogen equation, 30:1 is considered the perfect ratio for composting. Therefore, if the “C” is higher than 30, the organic material is considered a carbon source. If it’s lower than 30, it’s considered a nitrogen source.

Let’s say you have a small pile of straw to add to your compost pile. Straw’s C:N (carbon-to=nitrogen) ratio is somewhere around 80:1. Therefore, carbon-heavy straw is clearly a “brown.” You’ll find that brown material is often actually brown in color, such as cardboard and dried leaves. Carbon materials are the food (energy) for this hard-working crew.

The decomposers will need nitrogen to grow and reproduce. Look for organic materials that are below 30 on the carbon side of the C:N ratio. For example, grass clippings are about 20:1. Don’t let what looks like a high carbon number fool you; it’s below 30, so this is a good nitrogen source. Animal manure (from herbivores only) is around 25:1, and kitchen scraps are about 15:1. All these are excellent nitrogen materials for your compost pile.

The idea is to have a generally even balance between the two types of materials to help the microbial critters fuel up and get a hot compost pile going.

Here’s the part where I tell you to completely ignore the math. Don’t get bogged down with the number equations. Just add equal amounts of carbon and nitrogen materials to your pile, and nature will take it from there.

Water and Oxygen

The last two things necessary to create healthy, life-sustaining compost are water and oxygen. Most gardeners would like to get their hands on their compost as quickly as possible. For that to happen, you’ll want to have an almost equal balance of water and oxygen to create an aerobic or active compost pile.

The rule of thumb when it comes to watering a compost pile is to keep it just about as moist as a wrung-out sponge (around 40% moisture). If you can squeeze a drop of water out of a handful of organic matter pulled from the center of your pile, you’re good to go.

f you get a moisture level of 60% or higher, your pile may begin to smell because it’s becoming oxygen starved. The hardest-working bacteria in compost is the aerobic bacteria, and they’ll only hang around if you give them sufficient oxygen through aeration.

The best way to keep air in the organic matter is to turn all the material over at regular intervals. The simple task of lifting and turning the pile over introduces the right amount of oxygen.

Finished Compost

Eventually, the organic matter decomposes to the point at which the microorganisms have almost completely finished their work. The resulting compost (or humus) is dark and crumbly with a sweet, fresh-earth smell. The nutrients from the organic matter at this stage are easily accessible to plant roots.

If you've kept the pile balanced with carbon, nitrogen, moisture, and oxygen, it’s possible to have finished compost in as little as four weeks. On the other hand, if you decide to let nature do the heavy lifting, it might end up being six months to a year before it’s ready for the garden.