what is soil?courses.washington.edu/onsite/soils.pdf · soil horizons vertical cross section shows...
TRANSCRIPT
What is soil?
•Mineral matter, organic matter, soil water, and soil airmineral 45-49% (by volume)organic 1-5%water 20-30%air 20-30%
•Interface between atmosphere, lithosphere, biosphere and hydrosphere•Portion of the earth's surface consisting of disintegrated rock, humus
and living organisms
What is soil?
How do you describe soil?
How do you describe soil?
texture structuremineral/organic contentcolormoisturecharacteristics at depthporosity
Taken from Natural Resources Conservation Services Soil Survey Manualhttp://soils.usda.gov/technical/manual/contents/chapter3e.html
Soil texture
SAND – SILT – CLAY
Taken from Natural Resources Conservation Services Soil Survey Manualhttp://soils.usda.gov/technical/manual/contents/chapter3e.html
Soil texture
Methods to determine soil texture?
Soil Texture
Percolation test – covered in site evaluationThumb test/hand texturing – today Sieve Jar test/sedimentationSend to lab for particle size distribution
Soil structure
Following pictures taken from:Natural Resources Conservation Services Soil Survey Manualhttp://soils.usda.gov/technical/manual/contents/chapter3g.html
Figure from University of Minnesota websitehttp://www.soils.umn.edu/academics/classes/soil2125/doc/s3chap1.htm
Arrangement of peds or aggregates
Soil structure
Soil structure
Soil structure
Soil structure
Soil structure
Diagram taken from Natural Resources Conservation Services soil profile galleryhttp://www.mo15.nrcs.usda.gov/features/gallery/gallery.html
Soil Horizons
Vertical cross section shows horizons/layersDerived through weathering factors such as
rain, deposition, erosion, moving
O = organic matterA = topsoil, mineral surface layer with some
organicB = subsoil, mineral layer formed in place through
weatheringC = parent materialR = bedrock
The following photos of soil types and maps of distribution in US are taken from the Natural Resources Conservation Services Soil Classification website
http://soils.usda.gov/technical/classification/orders/Descriptions from Brady and Weil and University of Idaho
Soil Taxonomy
System for grouping and classifying soils Highest level of organization are 12 ordersOrders determined by degree of weathering and soil development
soils with little or no morphological development
Entisols
Inceptisols
humid and subhumid regions mountainous areassoils with weakly developed subsurface horizons
Andisols
soils formed in volcanic ashsurface horizon has high organic matter, dark colorlight, fluffy soils
Gelisols
soils with permafrost within 2 m of the surfaceyoung soils
Histosols
young, organic soils without permafrostbogs, moors, peats
CaCO3-containing soils of arid environments with subsurface horizon development
no water available for plants for more than 90 consecutive days
Aridisols
clay soils with high shrink/swell capacityhave deep wide cracks at some time of the year
Vertisols
calcium rich organic matter from dense root systems of grass vegetation
Mollisols
moderately leached soils with a subsurface zone of clay accumulation frequently formed in deciduous forests, but also grass savanna in Africa
Alfisols
moist, warm to tropical climatesstrongly leached soils
Ultisols
formed under forest vegetation
acid leaching of iron/accumulation of metal-humus complexes
Spodosols
intensely weathered soils of tropical and subtropical environmentshot climates, year-round moisture
Oxisols
hands on experience determining soil texture
hand texturing/ribbon test
Jeff HattenPhD Candidate Soils Science
College of Forest Resources
http://www.ext.colostate.edu/Pubs/Garden/07723.html