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