Erosion and Sediment Pollution Control Program Manual.pdf

Parent material—the weathered geological material from which topsoil and subsoil have been derived.
Percolation—the downward movement of water through a soil. Unless saturated with water, sandy
soils will have much higher infiltration and percolation rates than clay or compacted soils. But clay soils
have higher nutrient-holding and provision traits than sandy soils.
Permeability—the ease with which gases, liquids, or plant roots penetrate or pass through a mass of
soil.
pH—the degree of acidity (lower pH) or alkalinity (higher pH) of a soil. Most plant materials prefer
slightly acidic pH. Neutral is a pH value very close to 7.0; slightly acidic is 6.6–6.0; slightly alkaline is
7.4–8.0; strongly acidic is 5.0–4.0; strongly alkaline is 9.0–10.0; very strongly acidic is 4.0–3.0; and very
strongly alkaline is 10.0–11.0.
Surface or topsoil—the top portion of the soil usually moved in cultivation. The top 3 to 10 inches of
the soil is presumed to be fertile. A desirable topsoil should contain about 45 percent mineral material,
50 percent pore space, and 5 percent organic material.
Saturation—to fill all the voids or pores between soil particles with a liquid. Soils saturated for longer
periods can have poor aeration and high levels of CO2, both detrimental to root respiration and growth.
Resources
Brady, Nyle C., and Raymond Weil. The Nature and Properties of Soils. 14th ed. Upper Saddle River,
N.J.: Prentice Hall, 2007.
Craul, Phillip J. Urban Soils: Applications and Practices. New York: John Wiley and Sons, 1999.
Craul, Timothy A., and Phillip J. Craul. Soil Design Protocols for Landscape Architects and Contractors.
New York: John Wiley and Sons, 2006.
Elmendorf, William. Planting and After Care of Community Trees. University Park: The Pennsylvania
State University, 2001.
Elmendorf, William. A Guide to Preserving Trees in Development Projects. University Park: The
Pennsylvania State University, 2005.
Ramsey, Charles G., and John R. Hoke. Architectural Graphic Standards. New York: John Wiley and
Sons, 2000.
Sjoerd W. Duiker. Diagnosing Soil Compaction Using a Penetrometer. University Park: The
Pennsylvania State University, 2002.
Prepared by Bill Elmendorf, assistant professor of urban and community forestry.
AUTHOR’S NOTE:
Thanks to the University of California for the drawn illustrations used in this publication.
Visit Penn State’s College of Agricultural Sciences on the Web: www.cas.psu.edu, Penn State College
of Agricultural Sciences research, extension, and resident education programs are funded in part by
Pennsylvania counties, the Commonwealth of Pennsylvania, and the U.S. Department of Agriculture.
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