Just in case you've been too polite to ask your soil science friends, here's your answer:
What is soil judging?
Soil judging is the field component of soil science, a diverse discipline that combines geology, chemistry, physics, and biology. The study of soils helps us to better understand and protect the natural resource that sustains us all.
Essentially, soil judging is where one looks at a big hole or pit that has been dug out and analyzes the horizons of the soil (see above). Some characteristics that distinguish one horizon from another are color, structure, and texture. Using those characteristics and other factors such as clay content and the presence of carbonates, redoximorphic concentrations/depletions, gypsum, or salts, we can assign horizon names and subscripts to each horizon (ex. A, Ap, Bt, Btnk, Bss, Cr, etc).
Why should we care?
Looking at texture class and clay percentage in particular allows us to make conclusions about the soil's Hydraulic Conductivity (how easily water passes through the profile), Effective Soil Depth (how deep plants are able to extend their roots, excluding cracks or fissures), and more. Texture class again comes in handy when we analyze it in conjunction with Surface Runoff potential (itself a combo of Slope and Surface Hydraulic Conductivity). This pairing allows us to determine how suitable the soil would be for placement of a septic tank system, local roads and streets, and dwellings without basements.
For example, a soil with a low Surface Hydraulic Conductivity and a steep slope will have high Surface Runoff potential, because gravity will carry the water down the hill before it can be absorbed into the soil. This is usually true for clayey soils. Because it takes water a long time to pass through clayey soils, these are not suitable settings for septic tank systems, as "material" will pool and could cause clogging or overflow. Gross. Additionally, some clayey soils have a high shrink-swell potential, which means the wet shape and structure of the soil is dramatically different from the dry shape and structure. This behavior makes them very unsuitable for roads/streets as well as dwellings without basement. Generally, it's not desirable to have the ground shift significantly below your car or house every time it rains.
Of course, any explanation of the importance of soil science would be deficient if it did not mention agriculture. A soil's ability to support plant life is perhaps its most important contribution to human life. Soils sustain the plants that provide us food to eat, clothes to wear, paper to write on, timber to build home, and numerous other practical and aesthetic services.Also, it's fun!
Soil judging is a fun way to spend time outside, challenge your brain, and get your hands dirty!
