A Simple Soil Test

Soil“Dirt is merely soil out of place.” – Gardening Proverb  (Photo by Jim Richardson)

Contrary to all available evidence, this is indeed a blog about permaculture, not just a repository for confusing stories about why memory is like fish or how the human soul is a coyote in New Jersey.  So, in the interests of maintaining interest, here are some dirty words:

Whether you live in the northern or the southern hemisphere, now is a fine time to get some mulching done.  Ordinarily, the soil-building seasons of the year neatly complement the plant-growing seasons.  When your plants are dormant during the dry season or the cold season, the soil can be given your utmost attention.  Likewise, when the rains come or the warm air returns, you can leave the ground to more or less fend for itself while you focus your energy on the stuff growing out of it.  Try drawing a calendar of your local year, marking out the months of plant dormancy, regular rainfall, drought, killing frosts, and new plant growth.  Are there any markers other than the march of Gregorian months that signal to you when the processes of the land begin to shift?  What goes on in the nearby forests just before your outdoor spring greens come up?  Which species of birds appear right around the time the apples are ready for picking?  When do the frogs in your neighborhood start to sing, and what else happens at this time of year?

Perhaps this is not a good time to be focusing your attention on mulch.  Perhaps right now you have your hands full picking tomatoes or canning peaches.  We should all be so lucky.  For the rest of you, who currently find yourselves somewhere between the months of leaf-fall and first harvest, serenaded only by juncos and a flock or two of stubborn finches, I recommend a good long look at the state of your topsoil.  Gather up a large spoon and several transparent jars with lids.  In several different places in your yard, neighborhood, or other home ground, take a generous spoonful of topsoil, including any humus or duff lying on top.  Hold the spoon close to your nose and inhale deeply.  How would you characterize the odor?  Salty, spicy, “earthy”, rich, musty, Ranch-Style ™, pungent, rotten, petroleum-y?

The presence of different species of bacteria, fungi, and other microscopic beasts, as well as the mineral content of the soil, dramatically affects the odors it gives off.  Actinomycetes, a class of gram-positive bacteria similar in some regards to fungi, produce geosmin, the earthy smell of rich spring soil, and petrichor, the distinctive scent of the ground just after a rainfall.  Various species of anaerobic bacteria are largely responsible for the sulfurous stench of rotting compost.  As their name suggests, these bacteria thrive in conditions of low oxygen, such as those found in septic systems, airtight containers, and poorly-drained soils.  Earthworm spoor, visible to the naked eye as small piles of castings amid the bases of grass stalks and forb root corms, gives off its own unmistakable aroma.  Different species of worms produce different variations on the slightly spicy smell, and with some patience and attention to detail, you can figure out what the worms in your area are eating at different times of the year on the scent of their castings alone.  Fungal hyphae, the long fibrous strands that constitute the bodies of this kingdom of organisms, lend a slightly musty aroma to the soil around them.  Again, the trained nose can distinguish between different species and the different soil conditions they herald.  In general, the presence of abundant fungi in your soil indicates high, stable moisture content and perhaps an abundance of the plant chemical lignin, the substance that gives wood its durability.  Many fungal species are adapted to digest lignin, a feat impossible for all animal species and shared only by certain bacteria and protists.  Other odors portend different species and mineral characteristics.  If you’d really like to hone your nasal microbiological identification ability, I recommend A Field Guide to Bacteria, by Betsey Dexter Dyer.

Now, take that spoonful of earth and dump it in one of your jars.  Put another one in- go ahead, be decadent.  Now label your jar so you can remember where you got it.  Repeat elsewhere as desired.  Don’t mix spoonfuls of soil from different places.  Every square inch of soil is unique; on the scale of soil microorganisms, every acre might as well be a continent.  Now, return to your home laboratory or scullery or gaming parlor or wherever it is you perform your weird experiments and add some water to your assembled jars of dirt.  Rainwater or distilled water is preferable to tap water.  Many municipal water companies add biocidal chemicals like chlorine, fluoride, or arsenic to the drinking water.  These measures are necessary to kill the anaerobic pathogens that breed like mayflies in the polluted reservoirs many cities rely upon, and also to aid in communist brainwashing schemes.  Incidentally, where does your drinking water come from?  If you get if from a municipally maintained pipe network, where is the source located?  How is the water treated?  If your water comes from a well, in what rock formation is your aquifer located?  Where is it replenished?  Is it being depleted faster than it can regenerate, or is the outflow into your neighborhood matched by reliable rainfall?  Do you find yourself fantasizing about collective farms after a nice, cool glass of utterly harmless and definitely not contaminated water?  Bet you never thought mulch could be such a harrowing subject!

OK, now you’ve got several jars full of muddy water, and while they do make excellent gifts for people you intend to confuse, they can also tell you a great deal about the situation in your soil.  If you haven’t already done so, tightly screw the lids onto the jars, give ’em a good shake, and set them somewhere cool and out of direct sunlight.  If you are a seriously boring person, you can spend the next seven hours watching the water clear, and reflect on how all of life’s many worries and anxieties settle down and fade away in the serene grace of contemplative meditation.  The rest of you should go out and build a snow fort, or make flower crowns, or try to catch a squirrel with your bare hands.

It is a picture of a jar full of mud.

Welcome back.  By now your soil samples should be all but settled.  Notice how the larger, heavier particles are at the bottom, followed by layers of lighter, smaller particles, with a scum of twigs, leaves, and other biological debris at the surface.  The width, color, and density of each band of material indicates its relative abundance in each area you sampled.  Some places may have lots of bulky sand particles, others an abundance of medium-sized silt, and still others a high proportion of tiny clay particles.  Generally speaking, the blacker the color and the thicker the surface layer, the higher the organic content of the soil.  Red hues often indicate iron-rich strata, while green or blueish colors show the presence of copper, zinc, or magnesium.  Yellow sometimes indicates sulfur, though this is by no means a sure bet.  For more detailed information on the significance of the colors you see in your settling jar, contact your local USDA extension agency, permaculture guild, master gardener service, or neighborhood witch.

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One Response to “A Simple Soil Test”

  1. Thanks for your wonderful writing- just discovered this blog and learned so much in one reading. I’ll be collecting jars of soil this very day! And how could I obtain a sample of your brain chemistry, for use in a poultice on my own? And do you know of any source of information on mycoremediation of dog strangling infested areas, some of which I presently have under black plastic- not a solution I enjoy- I suppose I should just move on and let the invaders exhaust themselves or create their own new ecology here over the next hundred years? Here being a drumlin overlooking the Morganston plain, the former Lake Iroquois, and now drydocked halfway between Lake Ontario and Rice Lake, just west of the Trent valley, south of Salt and north of Cold creeks.

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