interpreting soils data - brightworkinc.networceste/documents/interpreting... · • observed in...
TRANSCRIPT
Interpreting Soils DataMaggie Payne
Resource Soil ScientistUSDA NRCS
Massachusetts Soil ConferenceHeifer Farm, Rutland, MA
September 17, 2015
Core Mission of the Soil Survey Program
1. Make an inventory of the soil resources of the U.S.2. Keep the soil survey relevant to ever-changing needs3. Interpret the information and make it available in a useful form4. Promote the soil survey and provide technical assistance in its use
for a wide range of community planning an resource development issues related to non-farm and farm uses
Soil Data Organization
Soil Survey Legend Consists of:• Soil Map Unit (with a minimum map unit size)
• Soil Component/Soil Series (estimate purity of map unit)• Soil Horizons (typical pedon for soil survey area)
• A• Depth, texture, color, pH, bulk density, Ksat…..
• B• Multiple data elements for each horizon
• C
Housed in NASIS – National Soil Information System
Soil Map Unit
Minor Components
Named Component
National Soil Information System
Pedon
Lab
Range
Forest
SoilMap
Manuscripttext
NASISdatabase
PlantData
SoilData
ClimateData
DOQs
Soil SurveyReport
CST
FOTG
CustomReports
SSURGO
Field Data CollectionPublic Data Customer
Products
Manage Soil Data
Analyze/Summarize
Crops
NASIS the “Data Management System”
Making this:
Into this:
Soils Reports and Interpretations:
• Soil Properties• Observed in the field or measured in the lab
• Sand, silt, clay fractions, organic matter, bulk density, flooding, water table
• Calculated Soil Qualities• Calculated based on soil properties
• Texture, Hydrologic soil group, T factor, Available water capacity
• Interpretations• Suitabilities and Limitations• Using observed or calculated data to predict soil behavior under defined conditions
• Uses outside research to determine which soil characteristics to use• Septic tank absorption fields• Vegetation suitability index• Suitability for excavated ponds
Soil Properties and Interpretations:
Calculated Soil QualitiesHydrologic Soil Groups (HSG)
4 groups according to the rate of water infiltration (A, B, C, and D):• Group A: high infiltration rate
• deep, well drained to excessively drained sands or gravelly sands
• Group B: moderate infiltration rate• moderately deep or deep, moderately well drained or well drained soils that have moderately fine
texture to moderately coarse texture
• Group C: slow infiltration rate• Usually have a layer that impedes the downward movement of water or a moderately fine or fine
texture
• Group D: very slow infiltration rate (high runoff potential)• clays that have a high shrink-swell potential, soils that have a high water table, soils that have a claypan
or clay layer at or near the surface, and soils that are shallow over nearly impervious material
• A dual hydrologic group (A/D, B/D, or C/D), the first letter is for drained areas and the second is for undrained areas. Only the soils that in their natural condition are in group D are assigned to dual classes.
Data elements used in the HSG calculation
• horizon depth• Ksat
• restriction depth• restriction kind
Data elements used• Flooding and Ponding frequency
and duration
HSG CalculationResults:
Interpretations
• Soil survey interpretations predict soil behavior for specified soil uses and under specified soil management practices.
• Laws, programs, and regulations • Broad land use planning
• The accuracy of the prediction depends on the how well the data is populated and the completeness of the criteria.
• Need to be written with the participant who works with the intended use
Soil Interpretation CriteriaStep 1. Define the Activity Step 2. Separate Aspects Step 3. Identify Site Features Step 4. List Soil Properties Step 5. Select the Number of Separations Step 6. Document AssumptionsStep 7. Develop the Criteria Table Step 8. Application, Presentation, and Testing
Creating Soil Interpretations
Define the Activity
• Sites should be dry and level to assure walking comfort and suitable sites for tables and benches.
• Deep soils are preferred to maintain suitable grass cover to overcome excessive compaction due to traffic.
• Picnic areas will use concrete tables and benches and small loaders will be used during placement.
• These sites may also be suitable for hiking areas and playgrounds. • The areas will encompass a minimum of 5 acres, however some may be as small as
1 acre. The interpretation will be used by the county for broad land use identification of areas suitable for picnic areas.
Creating Soil Interpretations
A town is looking to purchase land to create new park and recreational areas. They wish to design criteria that will identify sites suitable for picnic areas.
Separate Aspects
• What is considered?Is this an interpretation for installation ease, longevity, etc
• Do we need multiple interpretations?
Creating Soil Interpretations
Identify Site Features
There are factors that are not soil properties that will need to be considered – these are not written into a soil interpretation, but considered at a later time.• geographical location• rainfall totals• amount of surface stones
Creating Soil Interpretations
List Soil Properties• The soil properties impacting the site selection for picnic areas will
include those influencing water infiltration, soil water movement, properties that affect trafficability and vegetation growth.
Creating Soil Interpretations
• Organic matter• Flooding
• Stones• Permeability• Ponding
• Sand• Bedrock
• Depth to impermeable layer• Slope
• Gravel content• Acidity• Clay content
• Water Table
Evaluating Soil Properties• Soils with a water table from the surface to 50 cm are too wet• Soils with a water table greater than 200 cm from the surface are not too wet• Soils with a water table between the ranges will be evaluated using a sigmoid
curve
Creating Soil Interpretations
Select the Number of Separations• As a picnic area interpretation designed for broad land use planning, it is decided to create three
separations to be named “Not Limited”, “Somewhat Limited”, and “Very Limited”.
Creating Soil Interpretations
Document Assumptions• Document assumptions about the significance of the property and established values for
separating criteria. (a) A record of the significance of the water table and the slope properties(b) Indicate why the feature is important and why the specific break was chosen –
Why was 200 cm chosen? Why was 15 percent chosen?
(c) Establish values that are significant to the interpretation – based on research
Develop the Criteria Table• Assign feature and impact terms, and develop the criteria table
Creating Soil Interpretations
Property Limits Restriction
Not Limited Somewhat Limited Very Limited
Flooding None Others Freq, V. Freq Flooding
Water Table >200 50-200 <50 Too Wet
Texture S, LS, C, SiCL
Ksat
Slope <8 8-15 >15 Too Steep
• A landowner wants assistance in building a pond.
• Define the Activity:
Using Soil Interpretations – Example 2
• describe the activity or use; • identify the function(s) of the
activity or use; • define the desired performance
of the activity or use; • specify the soil depths that are
affected; • identify the type of equipment
for installation;
• Pond Reservoir Area• Livestock Water
• Hold water most of the year
• 3 meters (10 feet deep)
• D8 dozer
We have an interpretation for that: Pond Reservoir Rating Map
Using Soil Interpretations
Disclaimer:
Sometimes you’ve got to dig a hole
Using Soil Interpretations
Evaluating Soil PropertiesProperty Limits Restriction
Not Limited
Somewhat Limited
Very Limited
Perm 50-180cm
<1um/s 1-14 >14 Seepage
Bedrock >150 50-150 <50 BedrockTexture Marl Excess lime
Texture Gyp Excess gyp
Slope <3 3-8 >8 Too Steep
Using Soil Interpretations
Getting interpretive maps and reports
• Web Soil Survey
• Access Database from Geospatial Data Gateway
• Soil Data Viewer
Web Soil Survey
Web Soil Survey
Soil Access Database
Soil Data Viewer
Soil Data Viewer
Statewide maps – Website content
Developing new interpretations and reports
Are there certain soil properties that you need for a particular use?
We can make a report or interpretation for that!