13.Forest Soils Sampling (Standard Operating Procedure 13)
Shenandoah National Park Forest Vegetation Monitoring
This SOP gives step-by-step instructions for collecting a soil sample from each monitoring site,
completeing the section in Data Sheet H “Woody Debris and Soils Data” located in SOP 1,
Appendix 1B, and processing the soil sample upon return to the office. Soils strongly influence
many of the processes occurring within a forest ecosystem and are in return influenced by the
species present and inputs into the system (precipitation, nitrogen deposition, acid deposition,
etc). Thus, it is important to document soil properties and any changes in soils that may occur
over time. The goal of the soil collection is to gain an understanding of the soil characteristics
within the rooting zone present at each monitoring site in order to monitor stresses upon
13.2 Regulations Governing Sample Collection
The National Historic Preservation Act of 1966 (as amended) provides for the protection of
historical and cultural artifacts. Due to the random placement of sites, a soil sampling site may
impact a site of prehistoric or historical significance.
The park Archeologist or Cultural Resource Specialist must be contacted prior to a field season
during which soil samples will be collected in order to obtain permission to sample. If cultural
artifacts are encountered at a site, do not take soil samples. Code the site as not sampled and
record a site note explaining why soil samples were not taken.
13.3 Equipment List
Data Sheet H
Data Sheet C (for bearings of sides A and B)
Soil punch auger
Ruler (metric to 30 cm)
2.4 m PVC pole or 30m measuring tape
The following soils definitions are adapted from Sanders (2007). The soils of SHEN are
primarily Ultisols and Inceptisols. A soil profile may contain some or all of the following
horizons. However, in SHEN the E horizon is not often noticeable or even present, as is the case
in areas with Inceptisols.
Horizons – Layers which develop in the soil under the influence of climate, living organisms,
and other soil forming factors. Major horizons from top to bottom include the O (organic), A, E,
B, and C horizons.
O (organic) horizon – This is the collective name for the litter (Oi sub-horizon), duff (Oe sub-
horizon), and humus (Oa sub-horizon) layers, and is also sometimes referred to as the ‘forest
Forest floor – The top layer of organic matter overlying the mineral soil, consisting of intact and
partially decomposed litter and duff. The forest floor is another name for the O (organic)
Litter – Undecomposed or partially decomposed organic material that can be readily identified
(e.g., plant leaves, twigs, etc.). Litter is considered part of the O horizon as the Oi sub-horizon.
Duff – The layer of decomposing organic material below the leaf litter and above the mineral
soil. Duff is considered part of the O horizon as the Oe sub-horizon. This layer is distinguished
from litter by its degree of decomposition; within duff the origin of the organic matter can no
longer be identified (e.g., as leaves, twigs, etc.). The material in the duff layer is typically held
together by fungal mycelia.
Humus – Organic matter that has been decomposed to the point where it becomes stable, i.e.,
further decomposition will likely not occur. Humus can be present in all soil layers, although it is
primarily found in the O horizon as the Oa sub-horizon, and to a lesser degree, in the A horizon.
A horizon – Sometimes referred to as topsoil, this is the layer of soil located below the O
horizon and above the E horizon. This layer is primarily mineral soil, containing an accumulation
of organic matter that typically gives it a dark color. The A horizon is where seed germination
Mineral soil – Soil consisting predominantly of products derived from the weathering of rocks
(e.g., sands, silts, and clays). As soil develops under the influence of climate, living organisms
and other soil forming factors, it typically develops layers or horizons. Typical mineral soil
horizons include the A, E, B and C horizons.
E horizon – Typically the layer of mineral soil immediately below the A horizon; this layer is
generally lighter in color than both the A horizon and the underlying B horizon due to leaching
(eluviation) of minerals and fine materials by rainwater and organic acids from litter. Note: this
horizon is not noticeable (or even present) in some soils at SHEN.
B horizon – Typically the layer of mineral soil immediately below the E horizon; this layer is
generally lighter than the E horizon, formed by translocation and accumulation of material from
C horizon – The layer of mineral soil below the B horizon; this layer consists mainly of
unconsolidated parent material and is mostly unaffected by the biological and chemical processes
occurring in the above soil horizons.
13.5 Collecting and Recording Data
A two-person team comprised of a data recorder and a data collector can complete the tasks
described below efficiently.
Data Sheet Header
Enter the following standard information on the top of Data Sheet H (see SOP 1, Appendix 1B).
Site ID #: This is the unique five character name assigned to each site. It is the first five
characters after “NPS” stamped into the rebar caps at a site. Examples are 1L213 and 3L121.
Plot #: The plot to be sampled is always either plot 1, 2 or 3. This is the sixth character stamped
into the rebar cap on each corner post. For example the code 1L213-1-3 represents Site ID
1L213, Plot #1, Corner #3
Date (mm/dd/yyyy): Write in the month (2 digits), day (2 digits), and year (4 digits) in the form
shown. Include the forward slashes. Examples are 05/07/2007 and 09/25/2007.
Crew: Fill in the three initials of each person conducting the soil sampling using capital letters.
In order not to disturb the vegetation and soil properties and processes within the plot, soil
samples and duff thickness measurements will be collected from a band, 2 m wide and extending
from 2 m to 4 m outside of the plot along each of the four sides (Figure 13.1). Two samples will
be collected from each side of the plot, with more samples taken if soil volume collected is not
sufficient. The two sampling locations along each plot side can be located anywhere within the 2
m wide strip as long as the two points are at least 3 m apart. Collecting samples at a minimum of
two locations off of each plot side will help average any local variation in chemistry. In order to
have sufficient soil for analysis, collect a total volume of approximately 240 cm3 or 1 cup.
1. At the first sampling location, remove the loose leaf litter. Be sure to leave the duff layer
intact. With a soil sampling auger, core down at least 15 cm into the soil. Back out the
soil sampler and look at the core taken. The duff layer (part of the O horizon) is purely
organic and should not contain any mineral soil. Individual organic particles are usually
bound by fungal hyphae. The bottom of the duff layer is bordered by mineral soil.
2. Next, observe to see if the A horizon is distinguishable from the E and/or B horizons
(Figure 13.2). The A horizon is typically darker in color due to the included organic
material. If present, the E horizon is the zone of leaching of clay, iron, and other soil
compounds located below the A horizon. It is also generally lighter in color due to the
leaching of minerals. The B horizon is located below the A and E (if present) horizons. It
is the zone where leached minerals from above accumulate. A difference in texture
between the horizons may be noticeable and further aid in distinguishing among the
layers. If the horizons are not distinguishable, collect the upper most 10 cm of soil. Be
sure to discard the duff before collecting the A horizon.
3. Place the soil in a brown paper bag labeled with the date, site number, and collector’s
initials. Continue collecting at points along each side of the plot and measure the duff
depths at each collection point. All A horizon soil samples are placed together in the
same brown bag. Once complete, place the brown bag in a sealable plastic bag for
transport back to the office.
Soil Sampling Area
C1 Side A C2
Quad 1 Quad 2 2m
Side D SIde B
2m Quad 3 Quad 4
C3 Side C C4
Figure 13.1. Soil sampling area around each plot.
Soil Bag Labeled: Once the corresponding site number, date, and collector’s initials have been
written on the brown paper soil bag, place a check mark in the box.
Collector Initials: Record the initials of the person(s) collecting the soil samples.
Duff (cm): Record the thickness of the duff of each sample in tenths of centimeters in the blanks
provided within this table. Use only as many blanks as needed.
Circle: Note whether the samples are mainly from an identified A horizon or the top 10 cm of
the soil profile and circle the sample type.
Figure 13.2. An idealized soil profile. Adapted from Cornell Cooperative Extension (2006).
13.6 Field Checking
After all data have been collected and recorded, CAREFULLY check the data sheet for
omissions, unclear numerals, and any other mistakes. If a sample had no duff, write this on the
data sheet so that those entering this data know that a collection point was not skipped. After
current data are verified and considered free of all errors, initial in the top left corner (‘Field
13.7 Sample Processing
The following methods are adapted from Tierney et al. (2009).
On the day of collection
Upon returning to the office from the field, remove the soil sample brown paper bag from the
sealed plastic bag. Keep the sample in the paper bag and place it in the drying oven or in a safe
location to air-dry. If air-drying samples, leave soil sample bags open until soil no longer appears
moist. To do so, gently squeeze the soil from the outside of the bag to break up clumps, and
arrange the sample so it has maximum exposure to the air (fold back the lip of the bag, move soil
out of the corners of the bag, and let the sample lay as flat as possible). Soil sample bags should
always be open, unless in transit or completely dry. Bags closed for extended periods of time
may grow mold or other fungi, and may impact soil analyses.
Completing the drying process
As the soil dries, check and mix the sample daily by gently squeezing from outside the bag.
During the soil drying process, do not handle the soils with bare hands or allow contact with any
other potential contaminant.
When ready to dry in the drying oven, place open paper sample bags in oven set to 30-35° C (85-
95° F) until dry. Arrange sample bags and check as described above for air-drying. Clearly mark
the outside of the oven with a note identifying the date, a crew member’s name and contact
information, and the temperature at which the oven must remain. If more samples need drying
than can fit in the drying oven, keep the extra samples open, and in a safe, dry place. Monitor
samples in the oven and in the alternate location daily.
Once samples are dried, store them in a sealed plastic bag in the gas house freezer until a set of
samples are ready to be sent to a designated soil chemistry lab for analysis. Prior to sending
samples to the lab, prepare a master list of sample information. Assign each sample a unique
number from 1 to n, mark this number prominently on the bag (using a different color ink than
other info on the bag and circle this number), and create a list identifying which sample number
corresponds to which site number and date collected. Print a copy of this list for the Botanist, and
include a copy with the samples when shipped or delivered to the lab.
13.8 Sample Analysis
Dried samples should be sent to a designated soil chemistry lab for analysis. The designated lab
should have experience analyzing forest soils. The lab previously used by the forest monitoring
program was Brookside Laboratory (www.blinc.com) in New Knoxville, OH (client #52520).
The lab should prepare samples by passing each through a 2 mm sieve to remove larger particles.
Analysis must include the S001B and S171 packages of analyses. A minimum of 15 g of dry soil
is required for S001B, and 50 g of dry soil is required for S171. These analyses will provide the
following data for each sample:
percent sand, silt and clay
cation exchange capacity (a.k.a. total exchange capacity)
pH in water
SMP/Sikora buffer pH
% organic matter
elements (mg/kg) – S, P, Ca, Mg, K, Na, B, Fe, Mn, Cu, Zn, and Al
elements (%) – Ca, Mg, K, Na, and H
Cornell Cooperative Extension. 2006. How, when and why of forest farming; unit 2: site
assessment and non-timber forest crop selection; site assessment part II (soils). Available
0Part%20II%20(Soils). Accessed Jan 11, 2011.
Sanders, S. 2007. Standard operating procedure #11, soils in general vegetation monitoring
protocol for the Great Lakes Network, Version 1.0. National Park Service, Great Lakes
Network, Ashland, Wisconsin.
Tierney, G., B. Mitchell, K. Miller, J. Comiskey, A. Kozlowski, and D. Faber-Langendoen.
2009. Long-term forest monitoring protocol: Northeast Temperate Network. Natural
Resource Report NPS/NETN/NRR—2009/117. National Park Service, Fort Collins,
Revision History for SOP 13
Version numbers will be incremented by a whole number (e.g., Version 1.3 to 2.0) when a
change is made that significantly affects requirements or procedures. Version numbers will be
incremented by decimals (e.g., Version 1.6 to Version 1.7) when there are minor modifications
that do not affect requirements or procedures included in the protocol. Add rows as needed for
each change or set of changes tied to an updated version number.
Revision History Log:
Version # Date Revised by Changes Justification
1.0 5/8/2007 Nicholas Fisichelli
1.1 2/17/2008 David Demarest Wording
1.2 1/12/2011 Wendy Cass Added sections on soil Needed additional detail
Wendy Hochstedler processing and
Formatted to NPS-
Please cite this Standard Operating Procedure as:
Cass, W. B., N. A. Fisichelli, E. D. Demarest, and W. W. Hochstedler. 2011. Forest Soils
Sampling, Standard Operating Procedure 13, Version 1.2 in Cass, W. B., W. W. Hochstedler,
and N. A. Fisichelli. 2011. Shenandoah National Park Forest Vegetation Monitoring Protocol:
Version 2.3. Natural Resource Report NPS/XXXX/NRR—20XX/XXX. National Park Service,
Fort Collins, Colorado.