How to Test Your Soil - a Quick Primer

There's nothing like a sunny morning to help get you in the mood for some fun projects. When I headed out for the grocery store today, I saw that the parking lot of our local home improvement outlet was full of cars. Tubs of annuals were everywhere, and a long file of potted trees, shrubs and bushes stood like sentinels guarding piles of bagged mulch, garden soil and potting mix. A working spring weekend has come to the burbs in a big way.

Before you wander outdoors to take stock of the weed situation or drag the lawnmower out of the shed, think about the soil under your landscape plants for a second. Soil conditions can change somewhat from season to season, and if you haven't had your soil evaluated, or tested it yourself, this is a good time to get your hands dirty in a good cause.

Different Ways to Test Your Garden Soil

There are a number of ways you can get the straight scoop about your soil.

DIY - You can perform a simple test yourself using ingenuity, water and a jar (More on this in a minute). You can also purchase a handy soil test kit for around $15 that contains materials and instructions for a variety tests in key locations across your landscape (lawn, flower beds, vegetable garden) for details like pH and the presence of the big three: nitrogen, phosphorus and potassium.

USDA Cooperative Extension Office - If you just want a general sense of the type of soil conditions you're dealing with (if, say, this is your first spring in a new home), a quick call to your local Cooperative Extension Office will be helpful, too. The call is free. 

Web Soil Survey - If you have some time to dig -- with your computer-- visit the USDA's Web Soil Survey Page. You can find information there that will help you discover the mysteries of the soil in your area (there's a drill down) -- and develop a greater appreciation for the wealth of information to be found free of charge via government databases.

Jar and Water Soil Test - For the weekend warrior with a DIY approach to gardening, here's an interesting way to suss out the composition of your soil. If you have young children, this self-test method also makes for a dramatic and fun visual aid:

The idea here is to determine the constituent parts of your soil by creating a slurry and allowing the particulates to settle into layers (strata). The thickness of each layer will give you a good idea of your soil's composition.



What you'll need:

• A glass jar with a tight fitting lid (a mayonnaise jar or larger works well)
• Water
• Soil

Directions:

1. Fill the jar half full of soil (Remove any weeds or roots you see).
2. Add water to about one inch from the top.
3. Screw on the lid (tight).
4. Shake the jar until all the dirt particles are in suspension. (Don't stop too soon. Keep shaking for about three to five minutes or so.)
5. Set the jar on a flat surface for two to three hours.

After a few hours you'll see that the dirt has settled to the bottom of the jar with a little cloudy stuff still suspended on top.

The solid matter will be distributed in bands with slightly different textures and colors, which will tell  you the rough concentration of elements in your soil. The bands will consist of:

1. Floating layer: Organic matter
2. Top soil layer: Clay
3. Middle layer: Silt
4. Bottom layer: sand (and possibly some small rocks)

A good combination soil (loamy) will be composed of about 20 percent clay, with the sand and silt distributions just about even at 40 percent each.

Once you have an idea of the type of soil you're dealing with (you may want to test a number of areas in your garden for an accurate reading) you'll know better what amendments you need to add periodically. If your soil is mostly clay, don't despair. After a few seasons and a little work, you won't recognize it.



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Photo1 - Soil.jpg  Courtesy of Morguefile.com

Photo2 - GlassJar_Wiki.jpg  By Dwa_sloiki.jpg: Julo derivative work: Andrzej 22 (Dwa_sloiki.jpg)[see page for license], via Wikimedia Commons http://upload.wikimedia.org/wikipedia/commons/7/7d/S%C5%82oiczek.jpg