I have always loved soils, not the civilized brown loam of agricultural bottomlands but the problem children of this science.
I want to know what makes it so I can better learn how and why plants adapted to them as they did. In the desert, the soils are brutal, generally lacking in organic matter, which is essential to supporting healthy microbe populations. Most are so fast draining that nitrogen moves out just as quickly in solution, leaving nothing behind for long term plant nutrition. Unless you understand the nature of these soils, getting the plants you want to perform can be a real challenge and failure is all too frequent.
To really know a soil, it’s not what you see, but what you can’t see. That’s why the U.S. Soil Survey is such a valuable resource (http://websoilsurvey.sc.egov.usda.gov). Virtually all American soils are defined, and a huge range of maps allow you to zero in on your locale and determine exactly what soils are there and how the soils behave. Engineers depend on these maps for evaluating conditions for new endeavors from farms to underground buildings.