1. Adding compost to garden beds is the best thing we can do to improve soil fertility. Compost improves drainage in clay soils and increases water retention in sandy soils. It also increases soil microbial activity and, along with mulch, encourages earthworms, which do much of the work of soil building.

2. The composting process is most efficient (and the least offensive) when the ratio of brown stuff (dried leaves and grass clippings, hay, straw) to green stuff (fresh grass clippings, food scraps, manure) is about 3:1. You don't need to be finicky about this, it's just a guideline. A pile with mostly brown stuff will decompose very slowly, and a pile with mostly green stuff will probably smell. A good way to help make sure the children use these rough proportions is to add the material using buckets or wheelbarrow loads and carefully alternate three loads of brown with one of green.

3. The pile should occupy at least one cubic yard. This volume maintains enough heat in the center for faster decomposition.

4. Smaller materials, where more surface area is exposed to microbial action, will break down more rapidly. If possible, chop up materials before adding them to the pile.

5. Other "ingredients" often added to compost piles are thin layers of garden soil (to add more organisms), lime (to lower acidity), and (if there's an abundance of dry materials) high-nitrogen amendments such as alfalfa meal or cottonseed meal.

6. Avoid adding these to your pile: greasy foods, meat, bones, cheese, or dog or cat feces. The animal products attract other animals to the pile, and greases and oils interfere with decay. Pet manures may contain human pathogens.

Getting Started with Composting

Building the Pile
Compost piles can be freestanding or built in enclosures made from wire fencing, snow fence, wooden pallets, or lumber. If you're concerned about animal pests or odors, you can purchase a ready-made, enclosed compost system. However, properly aerated compost piles, free of animal products, shouldn't have those problems.

Many gardeners build their piles by alternating layers of materials. Although layering isn't necessary, making a compost "cake" helps children measure the relative amounts of different ingredients. Water each layer, then routinely keep tabs on the pile's moisture, keeping it about as moist as a wrung-out sponge. Have them find out what that feels like by wetting and wringing out sponges, then comparing them to the compost materials

Turn, Turn, Turn
Because the standard composting method relies on aerobic decomposers that require oxygen, you'll need to keep the pile well aerated. The best way to do this is to turn the pile. Using a pitchfork, mix up the materials as much as possible, trying to bring the outer materials into the center of the pile. You can also turn the pile by building a new pile right next to the original one. Kids can help by scooping materials with a bucket or using a shovel appropriate to their size.

Turning also helps speed decomposition by enabling all parts of the pile to benefit from the rapid decomposition taking place in the hot center. A pile with the right balance of materials and moisture, if turned every day, will compost completely in just a few weeks. A pile left to sit without turning could take months to decompose.

Taking its Temperature
As soon as you build a pile, invite your children to keep their eyes -- and hands -- on it. They can even take its temperature with the long probe of a soil or compost thermometer. The center of a well-functioning pile will heat quickly to 90 to 140° F. As one set of organisms consumes and breaks down the most readily degradable material, they produce heat. At that point, the more heat-loving microbes take over and thrive.

Spreading the Wealth
Compost is finished when it cools off and decreases to about a third of its original volume. It should be dark brown, soil-like, and exude an earthy smell. Your young diggers can help spread a 3- to 4-inch layer on top of the soil and mix it in.