Joe Ferranto, age 12, of Rochester, New York, for his question:

What is soil made of?

This popular question is a sign of the Dawning Age of Ecology. More and more enlightened young thinkers are aware that human happiness is rooted in the planet Earth. Here, the multitude of nature's wanders depend on a few basic necessities. One of these is the soil, which feeds the plants that provide our food and oxygen. You might expect such a vital item to require a finicky recipe. Not at all.

Nature creates soil from recycled waste products. The bulky ingredient is powdered minerals, eroded from the rocks by weathery winds and waters. This is mixed with an assortment of plant and animal material in various stages of decay. The patient blending needed to create healthy soil is done by earthworms, plus armies of decay bacteria and other small creatures. These busy blenders thrive by converting organic wastes into chemicals suitable for plant food. The whole thing sounds simple    but the earth requires about 100 years to create a layer of topsoil one inch thick.