Soil Improvement

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Soil Improvement

1. Have soil analyzed to help determine suitable plants and the need for any soil amendments.

2. Add organic matter to planting soil to enhance plant health.

This improves soil texture and moisture retention. (Soil rich in organic matter provides nutrients and micro-organisms beneficial to plants.)

For planting beds, spread 2 inches of organic matter and mix it in 6 inches deep.

For soil to fill a hole for planting shrubs or trees, mix 1/3 organic matter into the soil. (Some native plants may not require this, as they are well adapted to poor soils. Check with your supplier.)

Compost and composted sludge products such as Dillo Dirt are excellent sources of nutrients for ornamental landscapes. Such products release nutrients slowly to the plants, making frequent fertilizing unnecessary and minimizing the risk of fertilizer washing out of sites and becoming non-point source pollution. Dillo Dirt is a recycled material produced by the City of Austin at Hornsby Bend Sludge Treatment Plant.

3. Add other amendments as necessary.

Soils in the Austin area tend to be naturally rich in potassium.

A soil test is an important first step in determining whether fertilizer is needed, and if so, what type. (The addition of fertilizers containing potassium, for example, may be unnecessary or even harmful.)

To reduce the need for fertilizer on established turf, use the "Don't Bag It" program: leave clippings in place to decompose after mowing. This recycles important nutrients back into the soil.

The addition of gypsum and sand can improve the workability and drainage capacity of soil. Soils in the Austin area with large amounts of clay and stones are difficult to work with.

If little soil is available and bedrock is in evidence on the site, planting holes are sometimes dug in solid rock. If this occurs, be sure all planting holes drain thoroughly before planting. Standing water on plant roots can be lethal.

4. Choose topsoil wisely.

If topsoil is imported from off-site, be sure it is of high quality. (There are many grades of topsoil, and the end use will determine what type of topsoil to use. For example, the best material for grading and filling may not be good for planting.)

The natural clay type soils in our area are suitable for many native plantings. (Native plants are naturally adapted to such soils, and may not thrive on soil blends which don't mimic the natural conditions.)

Weeds and other pests such as fire ants can easily be imported onto a site via topsoil. Be sure to use reputable suppliers of soils who can verify their soil source.

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This file last updated on Sunday, May 11, 2003

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