The ABC's of Soil Science

If you want to know how to create better soil, you’ve got to learn basic soil science including information about soil color, texture and structure.

| June 11, 2013

Layers of Soil

There are different names describing soil textures, textural classes, each name is based on the proportion of sand, silt, and clay particles present.

Photo By Fotolia/Igrik

Reposted with permission from On Pasture.

Full confession: I am a soil geek. I love thinking about soil, working it, and smooshing it between my fingers. If you ask me a question about soil, I’ll bend your ear. Kathy and I were talking the other day, and she said she wasn’t completely clear about soil pH.  Who is? we wondered. And what about soil texture? Cation exchange capacity? Anions? Did you know that when you’re standing out on the pasture, half the soil’s volume is pore space, and only half is solid material? If any of these topics intrigue you, read on! The more you know about your soil, the better!

Putting names to things is a way of understanding them better.  In this case, we’re going to put names to soil characteristics as a tool for helping us understand our soil’s potential so we know what we can realistically expect from it.

To really understand soil, let’s see it as something with physical properties first and foremost. Not to sound like Julie Andrews in The Sound of Music, but let’s start with the ABCs of soil. When you read, you begin with ABC, when you sing, you begin with do, re, mi. When you think of soil, you can start with colortexture, and structure. Each property tells us something important about the soil.

Soil color comes from where and how it developed, and what minerals and materials it contains. Soils in cooler, wetter climates are usually grayer and browner in color. The colors may come from organic matter that hasn’t decomposed. Soils in dryer and hotter climates are usually lighter in color and redder. There, organic matter doesn’t stick around as long, and iron and other minerals have oxidized, showing off their brighter hues.

Soil color can be measured using fancy lab equipment or using something called a Munsell color book. The Munsell book is like a book of paint chips, ranging from reds and yellows to grays, greenish and bluish colors too. Each page and chip has a name. Clumps of soil are compared to chips to pick the color name for recording and management.  When soil is moist, though, it will be darker than when it is dry.

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