resource conservation, ecosystem health, sustainability

There are thousands of kinds of soil around the world. Each is unique, based on the material from which it was formed, the climate, the water features of the area, the vegetation, and other factors.

In a natural setting, the plants growing on the soil have moved in and developed in relation to the soil itself, so that there is a balance, a match between the plants and the soil. No amendments are needed because of this long term relationship.

In our gardens and yards, things are not often balanced. Development for human use involves all kinds of disturbance. Soil is dug up, pushed around, flattened . . . plants are ripped up, planted, mowed . . .

People begin to think about soil amendments when they want to do something the soil does not currently do well. For example, when someone decides to have a vegetable garden, they discover a number of things.

If the gardener decides to start putting plants in the soil as is, they may meet with success, or failure. Success occurs when the soil happens to be able to meet the plants' needs. Failure occurs otherwise. In many cases, soils do not meet the needs of non-native plants.

At some point, the gardener may have the soil tested. That is when they find out the pH (acidity) of the soil, or the nutrients in the soil are not a good match for the plants they want to grow. The soil may be too "heavy," making it difficult for plant roots to thrive.

What to do?

The two main options are

1. to amend the soil, adding what it does not have to meet the
plants' needs.
2. to build raised beds and make your own growing medium (a.k.a.
soil).

I have done both. My preference depends on my goals, and the site.

If I am planting something for the primary purpose of reducing erosion on a hillside (or any other such lofty goal), first I will look for plants that will grow in that soil, as is! That is the best option, for me.

However, if there is some reason I feel that I must use a plant not ideal for the site as is, I will find a way to amend the soil, preferably with plant materials, such as compost, and with companion plants that will continue to provide for each other as time goes by, so I don't need to trudge up the hill with a 50 pound bag of compost and a trowel every fall.

(I will return to discuss specific soil amendments later in this post.)

If my goal is to grow vegetables, because my site is so very stony, and I am no longer interested in proving myself by wrestling 250 pound stones out of the soil, I use raised beds and a growing medium based on recommendations of Mel Bartholomew, developer of Square Foot Gardening. Check out squarefootgardening.com.

Mel's Mix, as it is called, is a very productive combination of peat moss, coarse vermiculite, and compost that comes from as many sources as possible (cow, chicken, goat manure, leaves, etc.) From my background in soils and natural resources, and the way my plants grow in it, I can say this medium covers the bases well.

Worm castings are excellent in plant growing media, as are other plant materials and aged manures.

Raised beds should be deep enough that plant roots have plenty of room. They need to be where the plants will get enough, not too much, sun. They need to be away from larger plants that may "invade their space." They need to be well drained, unless you are growing wetland species.

Back to soil amendments:

If you, for some reason, really must amend the soil instead of using growing medium, here are some ideas: