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Soil Mulching

By Larry R. Sabata, Soil Scientist
Manhattan, Kansas

Mulching is the placement of any organic or inorganic material over the top of a soil surface to protect it.  Some of the benefits include: reduced soil erosion, less compaction, moisture conservation, increased control of soil temperature, and a reduction in weed growth.

There are many different types of mulching materials.  Some of these materials are readily available, while others can be purchased from various suppliers.  For example, grass clippings are a material that everyone has and are an excellent form of mulch.  There is one precaution however, do not use grass clippings from a lawn that has been recently sprayed.  Bark mulch, is a material that can be purchased from suppliers.  Bark mulch typically is more durable, lasts longer, and is more attractive in the landscape.  Inorganic mulches, such as various forms of gravel or ground-up road tires, can also be used but lack the soil improving properties that are often desired and obtained when the organic mulches break down.

Applying mulch depends on the result desired.  Mulches placed over the surface prior to summer will keep the area cooler than non-mulched soils.  In winter, the area containing mulch will insulate the soil to the point that frost penetration will not go as deep.  These same areas in spring will warm up more slowly.  Remember organic mulches will decompose over time and need to be reapplied when the results of the mulch are most desired.

How much mulch is needed?  Typically, a layer at least 1 to 3 inches deep is needed depending upon what type of application it is being applied (garden, trees, etc.).  Mulch is measured by the cubic foot.  For example, an area 10 feet by 10 feet, with a 3 inch application will need 25 cubic feet of mulch material.  There are mulch calculators on the internet that can be used to determine the area to be covered.

As in any soil management practice, there are pros and cons to using mulches.  The long term benefits of mulching are a positive practice that protects the soil resource and improves the landscape.  More information on soil mulching can be found on the Internet or contact any local university extension office for further assistance.

For more information on soil health, visit the Kansas Natural Resources Conservation Service (NRCS) Web site (www.ks.nrcs.usda.gov) or your local U.S. Department of Agriculture (USDA) Service Center.  To find a service center near you, check your telephone book under “United States Government” or on the Internet at offices.usda.gov.  Follow us on Twitter @NRCS_Kansas.  USDA is an equal opportunity provider and employer.