Glauconite
(Greensand)
A Peculiar Soil Constituent
Fred H. Bowers, Ph.D., Princeton Soil Institute
www.PrincetonSoilInstitute.com
What is Glauconite?
• Called Greensand Marl
• Sand-size particles or pellets (See figures below)
• Normal sand sized particles consist of discrete minerals such as quartz,
orthoclase, calcite, etc.
• Glauconite sand-size particles are made up of relatively stable pellets of claysize mica (Clay).
• The pellets generally range from about 0.5 to 0.05 mm in diameter with some
being as much as 4 mm cemented with clay-size siderite.
• Produces good structure when undisturbed
Distribution
• New Jersey has some
325,000 acres of greensand
(glauconite-bearing) soils
Water and Nutrient Characteristics
Water Holding Character
Table 1. Quantity of Moisture Retained in Various Soils and Greensand Deposits at Two
Tension Levels (unpublished data of Prof. N. A. Willits).
Soil
6 Atm Tension
% Moisture
15 Atm Tension
% Moisture
Sassafras
2.3
1.3
Hornerstown
20
16.4
NUTRIENTS: Contains up to about 7-8% potash (K2O) and, in some instances, a little
more (Hower, l.c.).
Effects of Glauconite on Septic
System Functionality
• Tricky Evaluations (due to texture by hand)
• Mottling
• Enhanced due to moisture holding
• Oxidation of reduced iron on peds
• Construction
• Smearing when constructing with backhoe
• Do it by hand
• Clogging and chemical changes
• Susceptible to deflocculation from salts from
water softener backwash
Soils of Glauconite Areas
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•
•
•
•
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Freehold
Collington
Colts Neck
Adelphia
Marlton
Kresson
How to Ensure a Functioning Septic
System in Glauconite
• Standard septic tank fields
– Mottling can suggest SHWT but not be accurate. Look at soil
series. Look at associated vegetation; Obtain a soil scientist
when in doubt
– Design disposal field as if it were clay (K class K0 for underdrain requirements)
– Do not smear or alter the glauconite. Dig trenches by hand.
• Drip irrigation into the upper soil horizons that avoid
flooding
• Lay down a layer of ASTM 33 sand on the glauconite
to form the biomat and form transition to clay
• Avoid using water softeners