Don’t Treat Your Soil Like Dirt

August 26th, 2014

We’re at one of the best points of the season now to dig a new garden bed or to renovate a lousy one – actually better than early spring when the soil can be cold and wet.

Don’t treat your soil like dirt… it’s one of the two keys to successful gardening.

I can’t emphasize enough how important it is to improve what you’ve likely got under there.

Especially in housing developments that have been heavily graded during construction, you’ve probably got 6 inches of clay and shale from the construction pile on top of packed subsoil.

That’s a death trap waiting to happen for all but the most abuse-tolerant species.

Healthy, nutritious and well drained soil is one of the two keys to successful gardening (the other being getting good plants in the right spots).

Look at it under a microscope and you’d see a living underworld of activity… strands of fungi swirling around plant roots, bacteria and nematodes breaking down bits of organic matter, tiny mites feeding on other microbes and so on.

It’s essentially a factory of life, and all the moving parts fuel one another. When people do things to disrupt that process – say, by stripping and regrading soil to build a house or by routinely dumping fungicides and insecticides.

If you’ve been dealing with struggling plants despite this year’s good growing summer or if you’re starting from scratch, now’s a good time to assess your soil.

One aspect is its nutrition makeup and acidity level, which you can assess by doing a Penn State soil test. Do-it-yourself kits are available for $9 to $10 from most garden centers, through county Extension offices or online from Penn State’s soil testing lab.

The results tell you what you’ve got, exactly what kind of fertilizer you need (if any), and whether you ought to acidify (sulfur) or make the soil more alkaline (lime). Otherwise, you’re just guessing.

The second aspect is soil quality.

Soil is a blend of minerals, air, water, organic matter and microbes that keep the “life factory” ticking.

The mineral particles come in three types – sand (the biggest particles), clay (the smallest) and silt (mid-sized). An ideal soil has a nearly equal mix of the three with the spaces between the particles ideally filled about half with water and half with air.

Why should you care about that? Because if your soil is too clayish, the small particles pack closely together and have limited pore space. Some homeowners have such compacted soil that it tests out near the denseness of brick – not an ideal medium for azalea-growing.

In rainy weather, water drains slowly through clay, fills the pore spaces and deprives the plant roots of oxygen. That means your plants suffocate and rot.

In sandy soil, the spaces are larger, water drains quickly, and the roots may dry out when rain or watering doesn’t happen regularly.

Either way, the best way to improve soil structure is to work compost, rotted leaves, mushroom soil or other organic matter into it. In clay soils, organic matter adds pore space to improve drainage, while in sandy soils, it acts as little “sponges” to slow drainage.

Some of the best soil-improving material can come from your own recycled yard waste. Now’s a good time to start a pile or three if you’re not already composting. Falling leaves and end-of-season yankings are excellent compost fodder.

Three at-home tests you can do to assess your soil quality:

   1.) Drainage test. Before planting, dig a hole about as big as one of the rootballs of the plants you plan to plant. Fill it with water and give it 24 hours to drain. Then fill it again and watch to see how many inches it drains per hour. It it’s not going down by at least 1 inch per hour, you’ve got some “uncompacting” to do.

Check your soil’s particle content with a simple jar test.

   2.) Soil-texture test. Dig up a tablespoon or so of soil and add enough water that you can roll it into a ball. If you can’t form a ball, the soil is sandy. Next, squeeze the ball between your thumb and index finger to make a ribbon.

The longer the ribbon goes before cracking, the more clay you’ve got. Less than 2 inches is a pretty good composition. More than 2 inches means the soil is clayish.

The feel alone can also give you a clue… sand feels gritty, clay feels sticky, and silt feels velvety slick.

   3.) Jar test. Dig 2 to 3 cups of soil from 6 to 8 inches deep in your soil. Let it dry on newspaper for 24 hours. Use a sieve or old metal colander to sift rocks, roots and other debris out of the soil. Crush lumps of soil to sift them through.

Pour 2 cups of the sifted soil into a quart Mason jar or clean mayonnaise jar and add 1 tablespoon of powdered detergent. Then fill the jar with water, seal and shake vigorously for 3 minutes.

After 1 hour, the biggest sand particles will settle out into a bottom layer. After 2 hours, the slightly smaller silt particles will settle out into a second layer. And after 24 hours, the smallest clay particles will settle out into a third layer.

Measure the thickness of each layer and the total depth. To figure the percentage of each layer, divide that layer’s thickness by the total depth. (Example: If all three layers total 3 inches and 2 inches of that is the clay layer, then about 66 percent of your soil is clay.)

Ideally, all three layers will be about the same. When any of the three exceed 60 percent, that type is becoming undesirably dominant, and amending is advised.

If you pass the soil tests, great. Consider yourself fortunate and plant away.

If you flunked, it’s time to loosen your beds down to 10 or 12 inches, break up any layering you’ve got going on between topsoil and subsoil, and add 2 to 3 inches of compost or organic material.

Incorporate it well, and improve the whole planting bed.

Don’t dig small planting holes and fill them with compost because water will drain down in quickly and back up when it hits the surrounding lousy stuff. Then your hole acts more like a bathtub, rotting those roots instead of encouraging them.

All of the digging and compost-lugging might sound like a lot of work (think of it as exercise instead), but it pays off in less plant mayhem later.

Be nice to your soil. Don’t treat it like dirt.