Organic Matter in Your Desert Soil

Desert soils tend to be dry, and bereft of organic matter. One of the main reasons is that the dry conditions and temperature extremes of the air and the soil do not provide good living conditions for plants and animals.

In more temperate regions, where there is moisture in the soil and temperature extremes are less, conditions are great for earthworms, insects, bacteria, fungi and other types of macro- and micro-organisms to live in the soil and use organic matter as food.

That food can be leaves, dead (and living) plants, the bodies of dead organisms large and small, or anything else that is organic in nature. The living organisms feed off the organic matter and turn it into humus and soil nutrients, which living plants can then use as food.

But organic matter in soil also serves other purposes.

In sandy, desert soil, organic matter takes up some of the space between the sand grains and binds them together. This increases the water-holding capabilities of the soil.

Conversely in clay soil, that is fine-textured, organic matter helps aggregate the clay particles, letting any excess water to drain easier, and to allow oxygen to penetrate the soil.

Many gardeners have adopted the position that adding clay to sandy soils and adding sand to clay soil will improve the soil texture. A far better way to improve your soil is by adding organic matter, until the soil itself has an organic content of three to four percent.

So how much organic matter do you have in your soil? There are a lot of variables. If the soil has been covered with native grasses for long times, then it will probably have a higher organic content.

Soil in native forests may have lower organic material, depending on how much under story growth.

Poorly-drained soil will generally have more organic matter than well-drained soil.

Soils in colder climates usually are higher in organic matter than those in warmer climates.

One of the best ways to find the content of organic matter in your soil is to have it tested. You can buy a kit to do this, but you’ll get more for your money if you have your soil tested by your local agricultural university. Check with your county cooperative extension agent to find out the specifics.

And, remember, if your soil is desert soil, you are probably going to have to amend it in some way. But also remember that it took hundreds of millennia to form that dry desert soil. Don’t expect it to change in one season.

Regular additions of organic material over several seasons will eventually change the soil’s organic composition. Continued application will help insure that it stays changed.

See also:

1. Color and Texture in Desert Soils
2. Does Your Soil Have Structure?
3. Drainage in Your Desert Garden
4. Visualizing a Desert Garden