Debbie Kutnink, age 12, of Independence, Kansas, for her question:
How thick is the earth's soil?
The plant world replenishes our air with fresh oxygen, provides our salads and vegetables and the food for our meat. and dairy animals. Without nature's green world of plants, all of us would soon perish from the earth. And the plant world depends on the earth's surface layers of rich soil. Everything in nature depends directly or indirectly on everything else. But without the rich brown soil, the world of living things would not have a chance to survive.
Nowadays we are thinking of ecology and the balance of nature. These thoughts lead us to realize that soil is a life and death item. It would be nice to know that the earth has soil in abundance to provide all the food crops humanity could possibly need. It would be nice to know that the soil is indestructible, never wears out or gets lost. But these pleasant notions are daydreams.
Our soil supplies are limited, and easily plundered. What's more, soil is a tricky blend of minerals and organic material and under normal conditions it takes nature about 100 years to create a layer one inch thick. When rivers flood they wash away tons of soil that took ages to develop. Often the flood waters dump this precious soil into the sea. More acres of good soil are depleted when stripped of their natural wild vegetation and robbed of richness by poor farming.
So let's pay our proper respects to the good brown soil and a good place to begin is with a survey of the supplies we have on hand. From our point of view, the useful layer is the surface topsoil, rich in plant food minerals. In most farm regions, it can be as deep as a cut with a spade. There are thicker layers in many valleys where rain has washed supplies dorm from higher slopes. High mountains have little or no soil and many deserts are covered with nothing but gritty sand. Deserts, rocky mountains, glaciers and other vast regions of the earth have no soil worth mentioning.
Compared with other countries, the United States has more than its share of rich topsoil. And our government has extensive plans to preserve our supplies arid expand them. The Soil Bank program encourages farmers to allow nature time to build up depleted areas. In the 1950s, more than 50 million acres were left uncultivated.
Such conservation programs add to our soil reserves for the future. But on a global scale, the earth's scanty soil cannot supply food for the hungry world and certainly there is not enough soil for the teeming future
The earth creates soil from powdered rocky minerals and organic materials from plants and animals. So far, we have not used these simple, plentiful ingredients to duplicate nature's soil recipe on a worthwhile scale. Our rebuilding programs call for conserving nature's scanty supplies by using good farming methods, allowing depleted acres to rest and recover and treating every little patch of precious soil with the respect it deserves.