Older than dirt

March 29,2006

What do LaToya Jackson, Heisman trophy winner Earl Campbell, and me all have in common?

We all turn 50 today!

That makes me think about soil science (stick with me, you'll see why in a minute.) I notice that there are many words that are used to describe soil: earth, ground, clay, duff, dust, loam, marl, mud, sand, silt, subsoil, topsoil, firmament, humus, sediment, till, gravel, gumbo, loess and dirt.

"Dirt" is a basic and important thing. In fact, it doesn't get any more basic or any more important than dirt. According to the wiki entry, soil is

Soil is material capable of supporting plant life. Soil forms through a variety of soil formation processes, and includes weathered rock "parent material" combined with dead and living organic matter and air. Soils are vital to all life on Earth because they support the growth of plants, which supply food and oxygen and absorb carbon dioxide and nitrogen.

Where does dirt come from? Lots of places. Composting for example. John Adams, our second president, once looked at someone's compost pile and said proudly, "This may be good manure, but it is not equal to mine."

Soil comes into existance via several processes. One mechanism for soil development occurs when recent lava flows in warm regions are exposed to heavy and very frequent rainfall. In these places plants become established very quickly on the lava, even though there is very little organic material. The plants are supported by the porous rock becoming filled with nutrient bearing water, for example carrying dissolved bird droppings or guano. The developing plant roots themselves gradually breaks up the porous lava and organic matter soon accumulates but, even before it does, the predominantly porous broken lava in which the plant roots grow can be considered a soil.

Much of this happens quickly, in far less than fifty years. So, in effect, I (and LaToya, and Earl) really am older than dirt.