"What is your soil?" is the new "What is your sign?"

Vertisol at the playground.  8-foot baby used for scale.  See the shrink/swell cracks?

I'm a Taurus, and I love asking people this question.  But more and more, instead of looking at the stars, I'm going to look you up via the ab-fab NRCS Web Soil Survey (WSS) to see what kind of soil you have.  


For example, I proudly (and digruntled-ly, given its issues with construction and amateur gardening) live on the state soil of Texas, the Houston Black clay, a Fine, montmorillonitic, thermic Udic Haplustert.  The "ert" in Haplustert means it is a vertisol- a shrink-swell clay (we've discussed the joys of this before).


Ultisol Analysis!
Anyways, my friend and fellow soil-o-phile over at the Bipartisan Victory Garden lives in Florida, and on the (drum roll please) Millhopper-​Urban land complex, 0 to 5 percent slopes! Ooooooh!  What does this mean for her?  Let us consult the WSS, shall we?


This series is a Loamy, siliceous, semiactive, hyperthermic Grossarenic Paleudult.  The "ults" in Paleudults means it belongs in the soil order Ultisol. Booooohhhhh.  Very sad.  Why? Ultisols are naturally low-nutrient soils.  Not only are there not many nutrients, it has a low cation exchange capacity (!), which means even if you add nutrients, the soil will have a hard time storing them.  However, there is a lot of good news.  Especially considering the woman on this soil- she can pay attention, and this soil responds well to good management.  Here is the good news-

• these soils are formed in areas with long growing seasons and plenty of water (this is where the "ud" in Paleudult comes from: humidity),
• the silicate clays in ultisols are usually not sticky (unlike my lovely smectite vertisol, sigh), meaning they are pretty workable,
• with lime (to counteract the soil's acidity) and proper fertilization (and compost, mayhaps?), this soil competes with the breadbasket mollisols and alfisols we all pine after ;-) HOWEVER, liming an ultisol to >6.5 pH can reduce phosphorus and micronutrient availability.  Why? Not sure yet.  It has something to do with precipitation of Ca or Mg phosphates.

Más definiciones:
Hyperthermic: >22 degrees Celsius average annual temperature
Thermic: 15-22 degrees Celsius average annual temperature
Ultisol: soils with low base saturation (<35%) and an argillic or kandic horizon (translocated silicate clay) or fragipan. Base saturation decreases with depth (reference).
Vertisol: Soil with 30% or more clay and that shrinks when dry (and cracks) and swells when wet.

Gardening on the Limestone rock land-Lozier association

A friend of mine lives on this soil association. What type of soil is this? It is pretty much just solid rock! My favorite quotation about this soil, from the archived El Paso County soil survey is this:

These very shallow soils have a surface layer of pinkish-gray, calcareous, moderately alkaline stony loam that is about 5 inches thick over limestone. All of this association is used as rangeland or for wildlife or recreation. Hueco Tanks Park, a recreational and historic site, is on the association.

I can't find the soil genetic line right now (a.k.a. it's proper name starting at the order level)

My first thoughts: There is no soil to garden here. Anyone trying to improve the soil for gardening is in it for the long-term ;-) So to grow any non-native plants, you'd essentially be container gardening. Bring in yer soil;  maintain moisture content with compost/organic matter; strategic water supply; protect with shade; use that humanure you bragged about.

What will your humanure do to this soil if incorporated long-term? Will its acidity help breakdown that limestone rock?  Hmmm....

Any other suggestions, other than head on over to the grocery store?

Enjoying the Archived PDF County Soil Survey

If you are someone who likes to read paper more than a screen, you may consider using the Archived PDFs of the County Soil Surveys instead of the online web soil survey.

From the archived Travis County survey, I found out that the soil under our house is part of the Blackland Prairie Texas ecosystem. We live on the Houston Black series, which is the state soil of Texas. Its usefulness in crop production is mentioned, and it also warns that its shrink-swell capabilities ... well, let me just quote it.

"The main limitations in use of the soils of this association in urbanization are the shrink-swell characteristics, as they affect foundations and streets; corrosivity, as it affects pipelines and cables; and the poor suitability of the soils for septic systems."

Our whole street is on this soil, and many of us are having foundation issues, and pipeline issues. The corrosivity that the survey mentions is showing up on our own rusted pipes.

Why is it corrosive? Is it more than just the high water holding capacity? Interesting...

Anyways, if there is anything for which you'd like to use your soil, you'll find it here in these soil surveys. Awesome!

Find out more about the soil under your feet; NRCS Web Soil Survey

Have you ever wondered about the soil under your feet, or somewhere else specific within the US? The USDA NRCS Web Soil Survey can answer SO MANY of the questions you may have about the soil of a small (10,000 acres or smaller) area. Learn things like the following:

• Native vegetation most adapted for the soil
• Recommended uses and limitations (e.g.:agriculture, building, recreation)
• Potential hazards (e.g.: prone to flooding, easily eroded, low fertility)
• Chemical and physical characteristics
  
• Name of the soil

It is quite easy to use and there are instructions on the home web page. Basically, this info is pretty much taken from the most recent county soil surveys, which have been written for almost all of the counties in the US and describes the types of info listed above. You can type in your address or graphically select the area you are interested in, instead of going the old-fashioned way and reading a map yourself. Reading the archived county soil surveys is easier for me when I am trying to learn about multiple soils within a larger area. You can also make pretty reports with some of the the same information using the Soil Data Mart.

Image found here: http://soils.usda.gov/technical/soil_orders/