Gee, it looks like snow, but it's too warm. What's going on? Salt bloom is what's going on. In low spots where the soil remains moist, as in some valley situations, evaporation concentrates dissolved salts. By capillary action, water from below then replaces the lost water, and the evaporation cycle continues. In areas where the ground contains large amounts of salt, common in our desert region, the salts accumulate, eventually forming a white blanket on the surface.
If current drought conditions continue in the Southwest, a related
problem will be seen in irrigated lands. Evaporation from river and reservoir surfaces
increases the concentration of salts in the water. Flowing onto the fields, further
evaporation takes place, and salt begins to build up in the soil. If sufficient water
is available, most of the salt can be flushed out of the soil. But when water is
scarce, the salts remain, building up with disastrous results for the crops grown on
these fields. In the Old World, whole civilizations apparently have been destroyed by
this salinization of the farmlands.
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.
Food and Agriculture Organization, United Nations.