USDANRCS 1 Field procedures consist of three parts Erosion assessment bare soil Soil compaction assessment area compacted Compaction type Soil sampling Forest floor and litter thickness ID: 807766
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Slide1
P3 Soil IndicatorMeasurement and Sampling
USDA-NRCS
1
Slide2Field procedures consist of three parts:
Erosion assessment:
% bare soil
Soil compaction assessment:% area compacted
Compaction typeSoil sampling:
Forest floor and litter thicknessForest floor sample collection
Depth to restrictive layerMineral soil sample collection0 – 4 in4 – 8 in
Soil texture
2
Slide3FIA Plot Diagram
Erosion and Soil compaction assessments are collected on all
4
subplots. Soil samples are collected from within the macroplot at 2, 3
, and 4 only.
Figure 1. FIA phase 2 plot diagram
Slide4% Bare Soil Estimation
25 %
25 %
25 %
25 %
Stand in the middle of the subplot and mentally divide the subplot into four quadrants.
Estimate the % bare soil in each quadrant.
% bare soil for the whole subplot =
∑ % bare soil in each quadrant / 4
Record in 5 % cover classes. “00” indicates no bare soil; “01” indicates trace amounts; “99” indicates that all of the subplot consists of bare soil.
Note: If the entire subplot is not forested, multiply the % bare soil by the % of the subplot that is forested.4Erosion Assessment
Slide5Bare Soil DefinitionBare mineral soil consisting of fine gravel (.08-20 inch or 2-5 mm), sand, silt, and clay sized particlesBare organic soil
Exclude rocks, bedrock outcrops, talusExclude cryptobiotic crustsExclude basal tree area and stumps (usually very small area)
5
Slide6% Bare SoilWhere collected: subplots 1, 2, 3,
4
When collected: any portion of the subplot contains at least one accessible forested condition class
Field width: 2 digitsTolerance: ± 10 %
MQO: 75 % of the timePDR codes:
00 none 25
21-25 55 51-55 85 81-8501 trace
30 26-30 60 56-60
90 86-90
05 01- 05 35 31-35 65 61-65 95 91-9510 06-10 40 36-40
70 66-70 99 96-10015 11-15 45 41-45 75 71-7520 16-20 50 46-50 80 76-806
Slide7Soil Compaction Assessment
% Area Compacted Estimation
Look for evidence of soil compaction on the subplot.
Estimate the % area of soil compaction in the subplot.
Record in 5 % cover classes. “00” indicates no soil compaction; “01” indicates trace amounts; “99” indicates that all of the subplot
soil is compacted.
Slide8Compacted Area Estimation
8
Compacted trail
Compacted area
Slide9% Compacted AreaWhere collected: subplots 1, 2, 3, 4
When collected: any portion of the subplot contains at least one accessible forested condition class
Field width: 2 digits
Tolerance: ± 15 %
MQO: 75 % of the timePDR codes:
00 none 25 21-25 55 51-55 85 81-8501 trace
30 26-30 60 56-60 90 86-9005
01- 05 35 31-35
65 61-65 95 91-95
10 06-10 40 36-40 70 66-70 99 96-10015 11-15 45 41-45
75 71-7520 16-20 50 46-50 80 76-809
Slide10RutTr Rutted
trail Ruts must be at least 2 inches deep into
mineral
soil or 6 inches deep from the undisturbed forest litter surface.
ComTr
Compacted Usually the result of many passes of vehicles,
trail animals, or people.ComAr
Compacted Junctions of skid trails, landing areas, work
area
areas, campsites, etc.Other Other An explanation must be entered in the plot notes.
Types of Compaction10
Slide11Types of CompactionWhere collected: subplots 1, 2, 3, 4
When collected: % compacted area > 00
Field width: 1 digitTolerance: no errors
MQO: 75 % of the timePDR codes:1 present
0 not present
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Slide12Examples of Compaction
Skid trail
Old ruts
Tire track
12
Slide13Soil Sampling Locations
Collect forest floor samples at soil sampling points in
macro
plots around
subplots 2, 3,
and
4.Collect 0-4 and 4-8 inch soil cores ONLY at sampling point in macro plot around subplot 2.
Subplot 2 soil sampling site: From the center of subplot 2, measure
30 ft on an azimuth of 180° (due south). Subplot 3 soil sampling site: From the center of subplot 3, measure 30
ft on an azimuth of 300° (northwest). Subplot 4 soil sampling site: From the center of subplot 4, measure 30 ft on an azimuth of 60° (northeast).13
Slide14Soil Sampling Restrictions
Collect soil samples only if soil sampling location is in a forested condition regardless of forested condition of the subplot
.
If cultural artifacts are present, do
not
collect soil samples.
Certain other conditions (e.g., obstructions, water on plot, safety) may preclude soil sample collection.14
Slide15Soil Sample Subplot Number, Condition Class, and Visit NumberWhere collected: all soil sample
locations
When collected: soil sampling site is in a forested conditionField width: 1 digit
Tolerance: no errorsMQO: At least 99 % of the time for subplot number and visit number; at least 95 % of the time for condition class
PDR codes:Subplot number: 2, 3, or 4Condition class: 0 to 9
Visit number: 1 to 9
Slide16Soil Sample Status
Where collected:Forest floor:
subplots 2, 3, and 40-4 and 4-8 inch soil cores:
subplot 2 only
When collected: soil sampling site is in a forested conditionField width: 1 digit
Tolerance: no errorsMQO: at least 99% of the time
PDR codes:1 Sampled2 Not sampled: non-forestThe following are for forested conditions:
3 Not sampled: too rockyNot sampled: water or boggy
Not sampled: access denied
Not sampled: too dangerousNot sampled: obstruction in sampling areaNot sampled: broken or lost equipmentNot sampled: other – enter reason in plot notes
Slide17Soil Sampling Equipment
Compass and measuring tapes
Small plastic tarp
Forest floor sampling frame (12-in diameter)
Knife for cutting forest floor layer and garden trowel
Soil sample bags, labels, indelible ink markers
Probe for depth to restrictive layer
Impact-driven soil core sampler (2-in diameter x 8-in depth) with two 2-in diameter x 4-in long stainless steel liners)
Cleaning cloth or tissuesPlastic water bottle and water for hand-texturing soil
Slide182
Side View
litter layer
humus layer
mineral soil
restrictive layer
3
1 forest floor
0 in
4 in
8 in
soil
samples
4
Depth Measurements
1=depth of forest floor2=depth of litter layer3=depth to a restrictive layer4=maximum depth of evaluation (20 in)
Top ViewN
WES
12 in
Soil Sampling
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Slide19Sampling the Forest Floor
Place the soil sampling frame on the ground at the sampling point.
Measure the thickness of the forest floor and litter layer (in) at the four compass points (N, S, E, W) on the inner edge of the frame.
Remove any
live
vegetation from the sampling area.
Using a knife, cut through the forest floor along the inner surface of the frame.
Using an inward scooping motion, remove the entire volume of forest floor from within the sampling frame.
Discard any woody debris (e.g., pine cones, large pieces of bark, twigs, etc.) larger than ¼ in in diameter. Also, discard rocks or pebbles.Working over the tarp, place the entire forest floor sample into a pre-labeled gallon sample bag(s).
Slide20Tips for Distinguishing Humus andMineral Soil
In some soils, distinguishing between the bottom of the forest floor (duff
layer) and the top of the mineral soil can be difficult.Look for the following:
Evidence of plant parts (leaves, needles, twigs, etc.). If you can see them decomposing in place, you are still in the humus layer.Rub the soil between thumb and finger - does it crumble (humus) or feel gritty (sand), silty, or clayey?
Shiny flecks of mica or quartz (won’t help in all soils).Subtle change in color - humus layer is black, mineral soil is more brownish.
Change in density – humus layer is light, mineral soil is more dense.
Slide21Forest Floor and Litter Thickness MeasurementsMeasure the thickness of the forest floor and litter layer at the four compass points (N, S, E, W) on the inner edge of the frame.
Slide22Distinguishing Litter and HumusLitter layer – Decomposing plant parts can still be identified (e.g., leaves, needles, twigs, etc
).
Humus (Duff)
layer – Plant parts can no longer be identified because decomposition has proceeded to the point where stable humus has been formed (dark color, crumbly, organic layer)
Slide23Forest Floor and Litter ThicknessWhere collected: soil sampling points in macro plot around
subplots 2, 3, and 4
When collected: soil sample status = 1
Field width: 3 digitsTolerance: ± 2 in
MQO: 90 % of the timeValues: 0.0 to 20.0
Slide24Depth to Restrictive Layer
Definition: A soil condition that limits root growth. This limitation may be physical (rock or hard pan), chemical (acid layer), or both.
Insert tile probe into center of sampling area and push it into the soil. Stop pushing when you encounter an obstruction and note depth.
Repeat at the N, S, E, and W edges of the sampling area.
Record the median of the five measurements (maximum = 20.0 in).
Special codes:Enter “00.0” if bedrock is present.
Enter “99.9” if soil is too rocky to insert tile probe.
Slide25Depth to Restrictive LayerWhere collected: soil sampling point in macro plot around subplots 2, 3, and
4
When collected: soil sample status = 1Field width: 3 digits
Tolerance: ± 6 inchMQO: 90 % of the time
Values: 0.0 to 20.00
0.0 Surficial bedrock present20.0
No restrictive layer found to maximum depth (20.0 in)99.9 Soil is too rocky to insert probe
Slide26Sampling the Mineral Soil
Prepare two zip-lock sample bags with labels for 0-4 in and 4-8 in samples.
Assemble soil core sampler with liners in place.
Drive soil core sampler to 8 in depth using the slide hammer attachment.
Remove soil core sampler from ground.
Disassemble the sampler and extract the soil cores from sampler.
Cut the cores so that they are flush with ends of liners.Place samples into appropriate bags.Clean the bulk density sampler and
liners.Use excavation method if soil is too rocky for bulk density sampler.
Slide27Sampling Problem Mineral Soils
Soils too rocky – Use excavation method. Collect same volume as core method. If coarse fragment content is high, collect more soil (double volume or fill sample bag).
Shallow soils – If soil is at least 4 in deep and not too rocky, use core sampler to collect 0-4 in depth in the lower soil liner (normally the 4-8 in soil liner). If soil is < 4 in deep, use excavation method.
Top liner (0-4 in) will not fill – Use core sampler to collect 4-8 in depth and excavation method to collect 0-4 in depth.
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Slide28Sampling Organic Soils
Organic soil: More than 8 in of organic matter on top of the mineral soil.
Typically associated with wetlands.
Because of the high moisture content of these soils, you may not be able to use the bulk density sampler (the soil will compress upon impact).
Instead:
Use a shovel to excavate a hole.Using a knife blade, collect material from 0-4 in and 4-8 in from the side of the hole.
Be sure to collect approximately the same amount of material that would have fit into the core.If available, a punch tube or Dutch auger may also be used.
Important difference: On organic soils, collect only the litter from the sampling frame as a forest floor sample.
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Slide29Soil Sample Collected by Regular Field Crew
State:
____ Unit:_____
County: ____
Plot #: ___
Soil Visit #:
__ Crew #: _______ Date: __/__/ ____ Subplot #: 2 3 4
Layer: Forest Floor 0 – 4 in 4 – 8 in Sampler: Bulk density Other
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Slide30Soil Texture
Definition: The relative amount of sand, silt, and clay-sized particles in a soil.
In the FIA program, we classify texture by “feel.”
This estimate is used in the soil loss equation to determine the potential
erodibility of the
soil.
0 – organic
1 – loam
2 - clay 3 - sand 4 - coarse sand30
Slide31Soil TextureWhere collected: soil sampling site in
macro plot around subplot 2
When collected: soil sample status = 1, subplot = 2
Field width: 1digitTolerance: ± 1 soil texture class
MQO: 80 % of the timePDR codes:0 Organic
1 Loam2 Clay
3 Sandy4 Coarse sand
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Slide32Microbes don’t know that they are in a bag. They will continue to eat, excrete, and otherwise go on with their little lives.
In time, decomposition will deplete the oxygen content in the bag, and cause the sample to go anaerobic.
These changes can alter the sample pH, exchangeable cation concentrations, and carbon and nitrogen contents.
So…
Send samples to the lab within a week of collection (regular mail is fine, no need to Fed Ex).
If you can’t send samples within a week, refrigerate them.
Care and Feeding of Soil Samples
32
Slide33NRS FIA Soil Samples Shipping Form
Name: _________________________ Shipped Via: _________________________
Signature: __/s/__________________ Tracking Number: _____________________
Date: __________________________Crew #: ______________ QA Status:
ٱ Standard ٱ Audit
State
County
Plot
Number
Date
Sampled
Layer Type(Forest Floor, 0-4 in, or
4-8 in)
Subplot
Number
(2, 3, or 4)
Bags/Sample
(note if more than 1 such as for large forest floor samples)
Slide34Requests from the Soils Lab
When collecting from multiple states, use a separate shipping form for each
state.
Use FIA state and county codes, not state postal abbreviation and county names.
Shipping form electronically sent should be printed and placed in shipping box. These are official documents for tracking purposes and need to be identical. One handwritten and one typed/printed is not acceptable, they need to match.
One sample, one row. If multiple bags for a sample annotate total number of bags in Bags/Sample column. Sample bags should be labeled [1 of 2, 2 of 2, etc
.]If no sample is sent, remove from shipping form.
Label box “FIA SOILS REFRIDGERATE UPON ARRIVAL”
Slide35Soil samples are sent to this regional lab:
John Larson
Forestry Sciences Lab1831 Highway 169 East
Grand Rapids, MN 55744Phone: 218-326-7113Email:jlarson@fs.fed.us
Shipping Soil Samples
Slide36APHIS
(Animal and Plant Health Inspection Service)
The shipment of soils from regulated areas (red) through non-regulated areas (white) is strictly regulated by USDA APHIS.
The responsibility for meeting federal regulations falls on the field crews
.
For
NRS - New York Crews
Slide37Soil Analysis
Once the samples are sent to the labs, what happens?
Forest floor:
Physical properties:
Bulk density
Water content
Chemical properties:Total carbon (organic)
Total nitrogen
Mineral soil:Physical properties:Bulk densityWater content
Coarse fragments (> 2 mm)Chemical properties:Organic and inorganic carbonTotal nitrogenpHExchangeable cations (Na, K, Mg, Ca, Al), metals (Mn, Ni, Cu, Zn, Cd, Pb), and sulfurExtractable phosphorus