NRES 201 Lecture 10 Outline of Last Lecture I. The benefit of taxonomyII. Soil ordersIII. Lower - level taxonomic categoriesOutline of Current Lecture IV. Soil spatial variability in the fieldV. Techniques and tools for mapping soilsVI. Making a soil surveyVII. Using soil surveysCurrent LectureSoil Variability -- Geographic contexto Soils are inherently heterogeneous in a multitude of properties and even at a micro-scaleo Vertical variability (profile characteristics) v. Horizontal variability (land management)- Small scale soil variability o Linked to topography, thickness of parent material layers, vegetation differenceso Within a farm field or across a residential lot- Landscape scale soil variabilityo Topography is a key factoro Drainage differences form a catena Sequence of soil types down a slop- Moderate drainage on top- Best drainage on slope- Poorest drainage at bottomo Never linked to land use for cropping or constructiono A drainage catena defines a soil association - group of individual soils that comprise a recurring landscape pattern- Regional scale soil variabilityo Primary controlling factors - climate, vegetationo Secondary controlling factors - parent materialTechniques and Tools for mapping soils - These notes represent a detailed interpretation of the professor’s lecture. GradeBuddy is best used as a supplement to your own notes, not as a substitute.1. The soil pita. Still the heart of soil mappingb. Excavation by hand or with a blackhoe2. Soil auguringa. Standard practice in soil mapping b. Making borings in strategic locationsi. By transect sampling relative to topography and vegetation.c. Hydraulic probes can also be used3. GPSa. Global Positioning Systemb. At least four satellites accessible from any pointc. Precise - determines position by timing satellite signals4. Ground Penetrating Radara. Detects contrasting subsurface soil layersi. By measuring reflectance of downward - directed electromagnetic wavesb. Eliminated the need for manual borings and their expensec. Unsuitable for some soils due to interaction of moisture, salt, and clay5. Air Photosa. Used as base maps for soil surveysi. Soil boundaries drawn directly on black and white ortho photographs that reveal buildings, roads, and streams1. Corrected for optical distortion2. Digital photos used for new surveysb. Source of supplemental soil informationi. Dark tones indicate moist, high - organic - matter surface soilii. Vegetation may be linked to soil typeiii. Drainage patterns usually reflect soil type and parent material6. Satellite Imagerya. Generated by computer processing of digital data from multispectral scannersb. Spectral scanning of different bands can identify: Vegetation types, surface soil properties, landform features,
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