News Release
August 6, 2007

Landscaping Tips: Good gardens and landscapes begin with good soil

By Kelli Belden, Research associate and director, UW Soil Testing Laboratory

Good soil is the foundation of a good garden or landscape, but many soils in Wyoming are less than perfect. Whether a gardener or landscaper plans to grow conventionally or organically, the organic matter content is one of the most important factors for improving soil quality.

Organic matter slowly decays to provide plant nutrients. It will improve water-holding capacity if the soil is too sandy, and it can improve porosity, infiltration and drainage if the soil is too heavy, such as those containing high percentages of clay. 

Because much of Wyoming has short growing seasons, cool temperatures and limited moisture, its soils rarely contain as much organic matter as the richer soils in the Midwest.  Fortunately, organic matter can easily be added in most situations. 

For annual beds or new perennial beds, incorporate a one-inch layer of organic material into the top 8 to 12 inches of soil when soil is prepared in the spring.

For new lawns, till 1 to 3 inches of organic material into the top 6 to 8 inches of soil.

For established perennial beds, a light layer of mulch allowed to decay will help maintain organic matter levels.   

For established trees and shrubs, 3 to 4 inches of organic mulch can be spread starting about 1 foot from the trunk and out to 6 inches beyond the “drip line” (the periphery of the canopy of a tree or shrub).   

There are many organic matter choices (manures, composts, wood residues, grass clippings, straw and peat), and each has advantages and disadvantages. 

Manures are high in nutrients but can also contain salts and weed seeds. Only well aged (6 months to a year) or composted manures should be used.  Because manures can contain pesticides and harmful pathogens, they should not be used on vegetable or fruit beds.

Composted vegetable waste from kitchens is another excellent source of organic matter for garden soils, but it degrades rapidly. Wood residues, including sawdust, and lawn clippings can be added to a compost pile if they do not contain harmful chemicals that may survive the composting process.

For tips on composting, see the University of Wyoming Cooperative Extension Service (UW CES) bulletin B-974R, Backyard Composting: Simple, small-scale methods. It can be found at www.uwyo.edu/ces/PUBS/b974R.pdf.

Printed copies at $4 each can be obtained by e-mailing the College of Agriculture’s Resource Center at bixbyd@uwyo.edu or calling the center at (307) 766-2115.

There are approximately 20 public compost programs in Wyoming, which are a good source for organic material. Call your local landfill for information.  

When incorporated into the soil, wood residues (fresh bark, chips or sawdust) used alone are long lasting but will tie up nitrogen. Straw also ties up nitrogen. One pound of nitrogen fertilizer should be added to the soil for every 100 pounds of straw or woody material incorporated. 

Sphagnum peat is acidic and may temporarily lower the soil pH, which can be of benefit in alkaline soils. Peat needs to be incorporated into the soil thoroughly, and it can be expensive.

No matter what organic material is used, it should be added every year to maintain the benefits.

Soil testing is an easy way to detect many problems before money is invested in gardening or landscaping projects, and the College of Agriculture provides this service.

Soil testing information sheets can be obtained at any UW CES county office in Wyoming (contact information is at http://ces.uwyo.edu/Counties.asp). They also are available online at www.uwyo.edu/renewableresources/soil/soil_lab.htm.

There is a $20 fee for the standard test, which includes pH, salts, organic matter, phosphate-phosphorus, nitrate-nitrogen, lime and texture. There is a $4 fee for additional tests. The lab can be reached at (307) 766-2135.

Contact: Robert Waggener, Editor
Phone: (307) 766-3571
E-mail: robertw@uwyo.edu

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