SOIL - Fundamental Concepts ABIOTIC Prepared by Earl D. Lockridge National Soil Survey Center Lincoln, NE Amended by: Mr. R

SOIL (Know this one) A mixture of mineral matter, organic matter, water, and air that originated from weathered bedrock and has become differentiated with depth into horizons Composite definition added Geomorphology book

SOIL Mature soil- clearly defined horizons produced by the weathering process. Each layer encroaches on the layer below it Paleosols - ancient soils removed from the zone of soil formation, usually by burial from younger sediments.

Major Components Mineral matter Organic matter Air Water

SOIL Component definition: Mixture of mineral matter, organic matter, water, and air. Example: Air 25% Mineral Matter 45% Water 25% Organic Matter 5%

CLIMATE and TIME –are the most important factors in soil formation bedrock- The igneous, metamorphic, and sedimentary components of the Lithosphere that may exist as mountains, cliffs, or low lying plains

Types of Bed Rock Igneous- rock from volcanic sources or locations…can be very old Examples- Granite & Quartz

Types of Bed Rock Sedimentary- rock formed by long term deposition by wind and water. Frequently found in layers. Examples- Sandstone & Shale

Types of Bed Rock Metamorphic- rock which has been altered by high heat or pressure Examples- slate (altered shale), gneiss (altered granite), diamond (carbon, coal)

parent rock- an area of bed rock that is the source of an area of soil

How do we get soils?

Over time the weathered material from the bed rock is covered by both living and dead organic material and a soil horizon develops in a dynamic way. These layer become characteristically differentiated over time due to climatic factors in their environment

Weathering Disintegration and decomposition of rocks by surface processes. Geomorphology book

Weathering Mechanical- the physical process of breaking apart rocks (frost/salt wedging, root growth) Chemical- breakdown through chemical alteration (oxidation, hydrolysis, acid inorganic or organic derived from Lichen, fungi, bacteria, mosses and all vascular plant roots) piru.alexandria.ucsb.edu/ ~tierney/TRS/lab6.htm –part of chemical definitdefinition taken form here

Factors that Affect Soil Structure Kind of clay Amount of organic matter Freezing and thawing Wetting and drying Action of burrowing organisms Growth of root systems of plants

Important Note All of these have a loosening effect on the soil, but they have no effect on aggregate stability

Soil Forming Processes Translocations Transformations Additions Losses

Only one millimeter of topsoil is created on 2 Only one millimeter of topsoil is created on 2.5 acres every year (The Way the World Works, 1996 )

Differentiated layer of developed soils are known as HORIZONS

The Horizons O- organic layer of decomposing plant material little mineral content A- Organic acid design decomposing the parent material giving it a dark color. This is the zone of leaching. Dissolved chemical carried down from the surface. Accessible by plant roots. Most soil organisms found here O A http://cr.middlebury.edu/biology/treeline/educ_dialogue/virtual_tour/orig_images/how/collectingSS/LongMonowRulerwarrows.jpg

The Horizons B- Zone of accumulation. More weathering then C. Parent material is hard to identify. Can be full of clay (more so then the above layers) and impermeable (red brown color common because of oxidation). Nutrients collect in this region-mineral leach up form the parent rock below B C web.unbc.ca/~quarles/ nres/soc/ggroup/hp.html

The Horizons C- Slightly weathered parent material (bed rock). Has not undergone leaching and accumulation to the same extent of above layers less oxidation then the B layer D or R- Bed Rock Bed Rock (Exposed) http://news.minnesota.publicradio.org/features/2005/05/09_steilm_rockmining/ml

O A B C nesoil.com/images/ massasoit.htm

Hint!! Not all layers of soil may be present, but if they are they will always be in the following order O-A-(E)-B-C-R (or D)

Three Fractions of Mineral Matter Sand 2-.5mm (diameter) Silt .49-.002mm Clay smaller than .002mm

USDA Textural Triangle

Examples of Soil Structure

Soil Color Indicator of different soil types Indicator of certain physical and chemical characteristics Due to humus content and chemical nature of the iron compounds present in the soil

loams – most fertile soil (silt, sand and clay in equal parts with partials of intermediate size)

Why is loamy soil best?

Porosity Porosity- the measure of how much water a rock can hold finer (silt, clay) the grain greater overall surface area so more porosity, more poorly connected however http://www.priweb.org/ed/pgws/systems/images/porosity.jpg

Permeability permeability- how easily the water can be transmitted http://www.earthnet-geonet.ca/glossary/display_term_e.php?term=permeability&showLetters=true permeability- how easily the water can be transmitted larger pores allow water to pass through easily (sand size and larger)

There are 20,000 different types of soil in the United States There are 20,000 different types of soil in the United States! (The Way the World Works, 1996 )

Local Soil Types

Pedogenic Pedogenic means pertaining to processes that add, transfer, transform, or remove soil constituents. http://earthquake.usgs.gov/image_glossary/pedogenic.html

Physical Properties of Soil Soil texture Soil structure Soil color Bulk density

Aspects of Soil Structure The arrangement into aggregates of desirable shape and size The stability of the aggregate The configuration of the pores

Factors that Affect Aggregate Stability Kind of clay Chemical elements associated with the clay Nature of the products of decomposition or organic matter Nature of the microbial population

Factors that Affect Soil Structure Kind of clay Amount of organic matter Freezing and thawing Wetting and drying Action of burrowing organisms Growth of root systems of plants

Important Note All of these have a loosening effect on the soil, but they have no effect on aggregate stability

Major Forms of Iron and Effect on Soil Color Form Chemical Formula Color Ferrous oxide FeO Gray Ferric oxide (Hematite) Fe2O3 Red Hydrated ferric oxide (Limonite) 2Fe2O3 3H2O Yellow

Bulk Density Determined by dividing the weight of oven-dry soil in grams by its volume in cubic centimeters The variation in bulk density is due largely to the difference in total pore space

Effects of Bulk Density Engineering properties Water movement Rooting depth of plants

Abiotic soil lab interpretation questions: 1. What soil layers were present at HWWP? 2. Which layer was thickest, which was thinnest? 3. How does the climate present in this area lead to the development of this type of soil? 4. How do you think this type of soil affect the life forms present in the HWWP (plants, animals, bacteria, and fungi)?