Soil, the foundation of a great garden

What is soil? Most people call it dirt. It brings to mind pictures of children's dirty faces or dirty floors or worse yet, germs and bugs and other nasties. And, in some ways those pictures are correct. But soil is so much more.

Soil is comprised of minerals, organic matter, microorganisms, space and water
The minerals are what we normally think of when we consider "dirt". It is really broken down rock. The type of rock determines the type of minerals available in the soil. The texture can be very fine clay, slightly larger silt, gritty sand or even rocks of various sizes.

The other major component of soil is organic matter. The amount of organic matter in the soil can vary dramatically. Organic matter is critical to healthy soil and is what provides the basis for the life of thesoil. Soil that is great for gardening is full of life. Good soil can have millions of organisms in as little as a teaspoon of soil.

The organisms available in your soil are like magic helpers. They help to build soil over time; some help make nutrients in the soil available to the plants; they help make the plants more healthy and fight diseases; they feed a chain of life that includes small mammals and birds. Learning to live at peace with the "bugs" can bring a whole new level of life to your garden.

You might be wondering how you determine what kind of soil you have. A good resource is to contact your local extension agency. They will be able to tell you what kinds of soil are in your area, what types of nutrients are typically available and what common practices are good for maintaining or building your soil for gardening.

You can also do a simple soil test to determine the texture. What you'll need:

  • quart jar (this is the size most mayonnaise comes in) with a lid
  • soil from the area you want to build a garden
  • water
  • clock or timer
  • marker to mark the jar

Here is the process:

  1. Take the quart jar and fill it 2/3 full of water. Then fill it with your soil
  2. Put the lid on it and shake for one minute to completely mix the soil and water
  3. Find a location where you can set the jar without it being disturbed
  4. After one minute, there should be a layer that has settled at the bottom of the jar. Mark a line at the top of this layer - this is the amount of sand
  5. Now wait one hour. There should be another layer settled on top of the sand. This is your silt. Mark the top of this layer.
  6. Wait 24 hours. There should be a third layer in your jar. Mark the top of this layer, which is your clay.

For our purposes, precision is not necessary. What you are really trying to learn is the general texture of your soil. When you look at the layers are they about equal or is there a lot more of one than the others? If you have a lot of clay or a lot of sand, the addition of organic matter is critical to help provide the basis for a healthy garden.

The other important component to determine is the nutrient level of your soil. There are several ways to determine your needs.

  • Your extension agent can give you a good idea if there are nutrients you may need to add to your soil
  • You can purchase a basic test kit from a garden center to test the soil. These are not precise but again, can give you a general idea of what you may need
  • You can have your soil tested by a professional. Check with your extension agent or a local garden center for a good place to have your soil tested

Besides nutrient levels, a soil test will also tell you the pH of your soil. For gardening, a pH between 6 and 7.5 is most desirable. If the pH is lower than 6, it will likely be too acidic for most garden plants. You can then add lime to help bring the pH up. If the pH is above 7.5, it may be too alkaline. In this case you can add sulfur to lower the pH. For specific details on adjusting pH, contact your extension agent or a talk to someone at your local garden center.

In the long run, the most important thing you can do for the health of your soil is add compost. Compost will correct any soil texture issues and provide nutrients for your plants that may be missing in yoursoil. I recently heard a gentleman speak who said we could pay $30 to have our soil tested or we could buy compost with that $30.