NRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use11NRES 201Soil Survey & Land Use2Today’s lecture topics- Soil spatial variability in the field- Techniques and tools for mapping soils- Making a soil survey- Using soil surveysSoil Survey & Land UseNRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use23Soil spatial variability in the fieldSoil variability in a geographic context- Soils are inherently heterogeneous- In a multitude of properties- And even at a microscale- Soil classification focuses on vertical variability- As related to profile characteristics- Soil survey focuses on horizontal variability- At meaningful scales for land management• That range from a few feet to many miles4Small-scale soil variability- Soil properties can vary markedly- Within a farm field- Or across a residentiallot- Variation at this scaleoften linked to:- Topography- Thickness of parentmaterial layers- Vegetation differences- Management historySource: Brady and Weil (2008)NRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use35Landscape-scale soil variability- Topography a key factor- Drainage differences form a catena- Sequence of soiltypes down a slope• Moderate drainageon top• Best drainage on slope• Poorest drainageat bottom- Never linked to landuse for cropping orconstructionSource: http://en.wikipedia.org6- A drainage catena defines a soil association- Group of individual soils that comprise arecurring landscape pattern- Named after two or three dominant soils in the group- Local example: Drummer-Flanagan association Source: Soil Survey of Champaign County, Illinois (1982)NRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use47Regional-scale soil variability- Controlling factors:- Climate- Vegetation- Parent material (secondary)(primary)Source: http://passel.unl.edu8Techniques and tools for mapping soilsThe soil pit- Still the heart of soil mapping- Excavation by hand or with abackhoe- Soil horizons identified fromthe pit face- Unsuitable for routine useSource: http://www.nrcs.usda.govNRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use59Soil augering- Standard practice in soilmapping- Borings made to locatesoil boundaries- By transect samplingrelative to topographyand vegetation- Hydraulic probes canalso be usedSource: http://wps.prenhall.com10Locating soil boundaries- Traditionally done using base maps,air photos, and a compass- Global Positioning Systems (GPS)are far more precise- Use a satellite network designedfor military navigation- At least four satellites accessiblefrom any point- GPS receiver determines positionby timing satellite signals- Positioning accuracy:• < 25 feet with hand-held receivers• < 2 inches with backpack unitSource: http://wps.prenhall.comNRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use611Ground-penetrating radar- Detects contrastingsubsurface soil layers- By measuring reflectance ofdownward-directedelectromagnetic waves- Eliminates the need formanual borings- And their expense- But unsuitable for somesoils due to interactionof moisture, salt, and clay Source: https://www.soils.org12Air photos- Used as base maps for soil surveys- Soil boundaries drawn directly on black-and-white ortho photographs that reveal buildings, roads, and streams• Corrected for optical distortion• Digital photos used for new surveysTurner HallSource: Soil Survey of Champaign County, Illinois (1982)NRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use713- Source of supplemental soil information- Dark tones indicate moist, high-organic-mattersurface soil- Vegetation may be linked to soil type- Drainage patterns usuallyreflect soil type and parentmaterial• Closely spaced gulliesand streams indicatelow-permeability claysoils and bedrock• Branched drainagepattern typical of siltysoils developed in loessSource: Soil Survey of Pike County, Illinois (1999)14- Direct sensing of soil properties- Based on near infrared reflectance(700-2500 nm)- Confined to the uppermost surface soil(2-20 mm depth)- Estimates:• Texture• Structure• Organic matter• Water• Salinity• Elemental compositionNRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use815Satellite imagery- Generated by computer processing of digital data from multispectral scanners- Now freely available through Google Earth®- Spectral scanning of differentbands can identify:- Vegetation types- Surface soil properties- Landform features- Water- Lower resolution than low-altitudeair photos, but the difference isdisappearing- Ground sample distance of 16-64inches with GeoEye-1Source: Google Earth®16What is a soil survey?- More than simply a soil map- Also a systematic examination, description, andclassification of the soils in a given area- The survey area is usually a county- But now the focus has shifted to Major Land Resource Areas (MLRAs)- Geographically contiguous land area with common soils, land uses, and climateMaking a soil surveyNRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use917Steps in making a soil survey- Mapping the survey area- Characterizing themapping units- Classifying the mappingunits- Correlating with othersurveys- Interpreting land suitability- Creating and releasing thereport18Map scales- Common scale for Illinois soil surveys is 1:15,840- 1 inch corresponds to 1,320 feet- And 4 inches to 1 mileSource: Soil Survey of Pike County, Illinois (1999)NRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use1019Mapping units- Soil phase- Subdivision within a soil series that focuses on a particular property that affects soil use• Such as erosion or slope• Examples:Source: Soil Survey of Champaign County , Illinois (1982)20- “Purity” of the mapping unit- A single soil phase must account for at least 50% of the mapping unit- Other phases can be present, provided they do not affect land management- Soil complexes- Group of contrasting soilseries represented bya single mapping unit- Their close proximityleaves no alternative- Soil complexes alsoused to represent soilphases subject to urbandisturbance Turner HallSource: Soil Survey of Champaign County, Illinois (1982)2171B Catlin-Urban land complex, 2-7% slopesNRES 201 Lectures 10-11 (Fall 2014): Soil Survey & Land Use1121Overview- National Cooperative Soil Survey began in 1899- Most counties surveyed at least once- Illinois soil surveys involve:- USDA Natural Resources Conservation Service (http://www.nrcs.usda.gov)- Illinois Agricultural Experiment