Making Compost ― Black Gold for Your Organic Garden

Thoroughly decomposed compost contains lots of humus — the beneficial, soil-improving material your plants need. Whether the original source was grass clippings, sawdust, animal manure, or vegetable scraps from your kitchen, all organic matter eventually becomes compost.

Making your own compost is probably the simplest way to ensure high quality compost and save some money. It's really not as complicated as you may think: The many commercial composting bins and containers on the market make it a mess-free and hassle-free process.

A well-constructed compost pile — built with the proper dimensions and maintained correctly — heats up fast; decomposes uniformly and quickly; kills many diseases, insects, and weed seeds; doesn't smell; and is easy to turn and maintain. Conversely, a pile just thrown together rarely heats up and, therefore, takes longer to decompose. This type of cold composting doesn't kill any diseases, insects, or weed seeds; may smell bad; and definitely looks messy.

Containing your compost pile makes it look neater, helps you maintain the correct moisture, and prevents animals from getting into it. You can build your own, as shown in Figure 1, or buy a commercial home composting unit.

The advantages of a commercial composter include the availability of a wide range of attractive sizes and shapes and ease of use. Choose from box-shaped plastic and wooden bins and barrels or elevated and easy-to-turn tumblers, as shown in Figure 2.

Store-bought bins are costly, however, and produce only small quantities of compost at a time, especially compared to a homemade bin that's built from scrap lumber or wire.

How to build a good compost pile

1. Choose a shady location. Make it out of the way, but still within view so that you don't forget about the pile. The soil under it should be well drained.
2. Make a bin. Create a wire cylinder that's 3- to 4-feet in diameter or build a three-sided box (similar to the one in Figure 1), that's 4 to 5-feet high and wide.
3. Add brown materials. Add a 6-inch layer of "brown" organic matter — such as hay, straw, old leaves, and sawdust — to the bottom of the container.
4. Add green materials. Add a 2- to 3-inch layer of "green" organic matter, such as green grass clippings, manure, table scraps, or even high-nitrogen fertilizer, such as cottonseed meal, on top of the brown layer.
5. Repeat these layers. Water each layer as you go, until the pile is 4 to 5-feet tall and fills the bin. A smaller pile won't heat up well and a larger pile can be difficult to manage.
6. Within two days, mix the layers together thoroughly. Particle size should be varied, smaller particles hasten decomposition.
7. Cover the pile with a tarp. This keeps rain away and preserves moisture. If the pile gets too soggy or too dry, it won't heat up.

What to add, and what not to add

What to add to the pile or composter

• Hay, straw, pine needles
• Leaves
• Kitchen scraps (egg shells, old bread, vegetable and fruit scraps)
• Animal manure, except for dog, cat, pig, or human
• Old vegetables, flowers, or trimmings from trees and shrubs
• Sawdust
• Wood chips
• Weeds
• Shredded black-and-white newspaper. (In the past, color printing used heavy metals in the ink. Most color printing now uses soy-based inks, but it's better to avoid them in the garden altogether to be on the safe side.)

What not to add

Avoid adding the following to your compost bin:

• Kitchen scraps like meats, oils, fish, dairy products, and bones. They attract unwanted animals, such as rats and raccoons, to the pile.
• Weeds that have gone to seed or that spread by their roots, such as quackgrass
• Diseased or insect-infested vegetable or flower plants
• Herbicide-treated grass clippings or weeds
• Dog, cat, or pig feces

Ratios for adding materials to the compost pile

Although nearly any combination of organic materials eventually decomposes, for the fastest and most efficient compost pile in town, strike the correct balance (C/N ratio) between the two types of material — usually 25 to 1 (that is, 25 parts carbon to 1 part nitrogen).

Table 1 shows which common compost materials are high in carbon and which materials are high in nitrogen. Notice that the softer materials, such as fresh grass clippings, tend to be higher in nitrogen than hard materials, such as sawdust. Mix these together to form a pile with an average C/N ratio of 25-to-1 to 30-to-1, and you'll be well on your way to beautiful compost.

Use the following carbon/nitrogen ratios as guidelines. Actual ratios vary depending on the sources of the materials and other factors. And speaking of sources — be sure that your compost materials haven't been contaminated with pesticides or other chemicals.

Quick and easy compost recipes

• Recipe #1: Four parts kitchen scraps from fruits and vegetables, 2 parts chicken or cow manure, 1 part shredded newspaper (black ink only), and 1 part shredded dry leaves.

• Recipe #2: Two parts kitchen scraps, 1 part chicken manure, and 1 part shredded leaves.

• Recipe #3: Two parts grass clippings, 1 part chicken manure, and 1 part shredded leaves.

Keeping your compost pile happy

1. Keep the pile moist by periodically watering it. Dig into the pile about 1 foot to see if it's moist. If not, water the pile thoroughly, but not so that it's soggy. The pile needs air, too, and adding too much water removes air spaces. If you built the pile with moist ingredients, such as kitchen scraps, it won't need watering at first.
2. Turn the pile when it cools down. Using a garden fork, remove the outside layers and put them aside. Remove the inside layers into another pile and then switch. Place the outside layers in the center of the new pile and the inside layers along the outside of the new pile.
3. Let it cook again. How hot it gets and how long it cooks depends on the ratio of C/N materials in the pile and whether you have the correct moisture levels.
4. When it's cool, turn it again.

You should have finished compost after two to three turnings. The finished product should be cool, crumbly, dark colored, and earthy smelling.

• The pile was too wet or dry.

• You added too many carbon materials and not enough nitrogen materials.

• The pieces of material were too big or packed together. Shred leaves, branches, and pieces of wood to decompose more quickly.

• The pile was too small.