Soil Improvement

Dirt in Hands
A little dirt in your hands will help you understand how to water the soil in your landscape.

Soil improvement is a key Xeriscape™ fundamental!

Soil is like a foundation. Everything you do to manage plants in your landscape depends on the soil that supports them. Soil, water, and plants work together to create a living system. To find out what kind of soil you have, test the soil in your backyard.

Soil Texture Test:

Squeeze a moist (rather than dry or muddy) ball of soil in your hand. Press the soil between your thumb and fingers. You'll be able to identify one of these textures:

Conditioning your soil is important for water conservation and good plant growth.

Soils are mixtures of materials and are seldom all one kind or another. An "ideal" soil is 45% minerals (clay, silt, and sand particles; 5% organic matter; and 25% each water and air. Soils are highly variable. Soils in one area will be different from those found in another. Your soil may be different from your neighbor's. You may even have move than one kind of soil in your own yard. Construction activity often leaves a soil that is far different from the original soil. It is usually deficient in organic matter and fertility.

How fast does your soil drink water?

Soils - like people - drink at different rates. Thousands and thousands of gallons of precious and costly water are wasted each growing season by people who apply water faster than soils can absorb it.

Most lawn sprinklers discharge water at a rate of more than 1 inch per hour. Highly compacted, tight soils; soils that are already full of water; or thatched turf cause water to run off. Here is a guide to how quickly different soils absorb water:

Well, then, how do I improve my soil so I don't waste water?

Loosening the soil by rototilling or spading will help. Adding organic material at the same time will keep the soil loose for a healthier lawn. For newly constructed areas, a minimum of 1 inch organic material (3 cubic yards per 1000 square feet) should be tilled in to a depth of 6 to 8 inches. Greater amounts may be desired for planting beds.

What type of organic material?
All of the following organic materials will work, some better than others, and some are less expensive than other:

Check with your local extension agent for additional details.

Can soil under existing plants be improved?

This is difficult to do. It is best to improve soil before planting. But it is possible to improve soil under existing plants, given a lot of labor and some special equipment.

Existing soil can be aerated to open the soil. Manual spike-like devices can be inserted into the soil. Some take cores or plugs out. Some inject water. Others use high-pressure air to fracture the soil. Organic materials can be injected into the subsoil. There are even special machines to help do this. Coarse sand can be used to fill the holes, to extend the longevity of the aeration, and to increase water infiltration (turf will grow over the holes rapidly).

New technology is developing

Recent products have been developed, and more new products will be available over time, that will help soil absorb and hold water, and make it available for plant use.

As these new products are improved and more widely used, costs should decrease. Consumers are advised to thoroughly research new products before buying and using large quantities. As with any product, some work better than others, and all require special precautions.

Xeriscape™ is the trademark of the National Xeriscape Council, Inc.