Gardeners from moister climes are faced with all sorts of desert surprises. The sheer speed of water evaporation is one, of course. However, even the very soil is seldom what outlanders expect. In the valley bottoms, rapid changes between sand, silt, clay, and gravel, reflect past meanderings of the river, and different treatments may be necessary in areas separated by a few feet. High water tables may produce dying plants and a whitish bloom on the soil. Salt-bearing water, drawn upward by capillary action, evaporates, depositing minerals with disastrous results.
On valley and bolson slopes, a hard, whitish substance--the infamous
caliche--cements rocks and soil particles into a layer impervious to water and roots.
Throughout, except in areas of river bottom that once were wetlands, soil organic
matter is scanty, and if added by the gardener, soon decays in the heat. Lacking
organic matter, the very structure of the soil, so important for fertility, is
degraded. All in all, a difficult place to practice agriculture. And just think how
much more difficult for Native Americans before modern technology!
Contributor: Arthur H. Harris, Laboratory for Environmental Biology, Centennial Museum, University of Texas at El Paso.
Desert Diary is a joint production of the Centennial Museum and KTEP National Public Radio at the University of Texas at El Paso.