NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use NRES 201 Soil Survey Land Use 1 Soil Survey Land Use Today s lecture topics Soil spatial variability in the field Techniques and tools for mapping soils Making a soil survey Using soil surveys 2 1 NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use Soil spatial variability in the field Soil 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 miles 3 Small scale soil variability Soil properties can vary markedly Within a farm field Or across a residential lot Variation at this scale often linked to Topography Thickness of parent material layers Vegetation differences Source Brady and Weil 2008 Management history 4 2 NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use Landscape scale soil variability Topography a key factor Drainage differences form a catena Sequence of soil types down a slope Moderate drainage on top Best drainage on slope Poorest drainage at bottom Never linked to land Source http en wikipedia org use for cropping or construction 5 A drainage catena defines a soil association Group of individual soils that comprise a recurring 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 6 3 NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use Regional scale soil variability Controlling factors Climate primary Vegetation Parent material secondary Source http passel unl edu 7 Techniques and tools for mapping soils The soil pit Still the heart of soil mapping Excavation by hand or with a backhoe Soil horizons identified from the pit face Unsuitable for routine use Source http www nrcs usda gov 8 4 NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use Soil augering Standard practice in soil mapping Borings made to locate soil boundaries By transect sampling relative to topography and vegetation Hydraulic probes can also be used Source http wps prenhall com 9 Locating soil boundaries Traditionally done using base maps air photos and a compass Global Positioning Systems GPS are far more precise Use a satellite network designed for military navigation At least four satellites accessible from any point GPS receiver determines position Source http wps prenhall com by timing satellite signals Positioning accuracy 25 feet with hand held receivers 2 inches with backpack unit 10 5 NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use Ground penetrating radar Detects contrasting subsurface soil layers By measuring reflectance of downward directed electromagnetic waves Eliminates the need for manual borings And their expense But unsuitable for some soils due to interaction of moisture salt and clay Source https www soils org 11 Air photos Used as base maps for soil surveys Soil boundaries drawn directly on black andwhite ortho photographs that reveal buildings roads and streams Corrected for optical distortion Digital photos used for new surveys Turner Hall Source Soil Survey of Champaign County Illinois 1982 12 6 NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use Source of supplemental soil information Dark tones indicate moist high organic matter surface soil Vegetation may be linked to soil type Drainage patterns usually reflect soil type and parent material Closely spaced gullies and streams indicate low permeability clay soils and bedrock Branched drainage pattern typical of silty soils developed in loess Source Soil Survey of Pike County Illinois 1999 13 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 composition 14 7 NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use Satellite imagery Generated by computer processing of digital data from multispectral scanners Now freely available through Google Earth Spectral scanning of different bands can identify Vegetation types Surface soil properties Landform features Water Lower resolution than low altitude air photos but the difference is Source Google Earth disappearing Ground sample distance of 16 64 inches with GeoEye 1 15 Making a soil survey What is a soil survey More than simply a soil map Also a systematic examination description and classification 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 climate 16 8 NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use Steps in making a soil survey Mapping the survey area Characterizing the mapping units Classifying the mapping units Correlating with other surveys Interpreting land suitability Creating and releasing the report 17 Map scales Common scale for Illinois soil surveys is 1 15 840 1 inch corresponds to 1 320 feet And 4 inches to 1 mile Source Soil Survey of Pike County Illinois 1999 18 9 NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use Mapping 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 19 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 2171B Catlin Urban land complex 2 7 slopes Group of contrasting soil series represented by Turner Hall a single mapping unit Their close proximity leaves no alternative Soil complexes also used to represent soil Source Soil Survey of Champaign phases subject to urban County Illinois 1982 disturbance 20 10 NRES 201 Lectures 10 11 Fall 2014 Soil Survey Land Use Using soil surveys Overview 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 Station Illinois Department of Agriculture 21 The county soil survey report General soil map Shows soil associations grouped by physiographic region At a scale of 1 100 000 to 1 250 000 Index map For