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Soils 101
Question | Answer |
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Functions of Soil in our Ecosystem (6 Functions) | Supports the growth of higher plants Controls the fate of water in the hydrologic system Nature’s recycling system Modifier of the atmosphere Habitat for living organisms Engineering medium |
A ___ is a three dimensional natural body, is formed by natural processes, and has unique features that distinguish it from surrounding soils | soil |
The ___ is a collection of all these natural soil bodies | soil |
Soil is made up of __, __, __, and __. | air, water, minerals, organic matter |
Sand, silt and clay make up the soil ___. | texture |
Soil ___ is the arrangement of sand, silt, and clay particles to form larger aggregates or peds. | structure |
Soil ___ is usually not total destruction of soil, but loss of ___. | degradation, quality |
____ is a biochemical and physical process that involves both ___ and ___. | weathering, destruction, synthesis |
___ rock is formed from molten magma | igneous |
___ is formed when weathering products of older rocks collect under water (sediments) and are consolidated into new rock. | sedimentary |
___ is formed when igneous and sedimentary rocks are transformed under heat and pressure into new rock | metamorphic |
___ processes break minerals and rocks into smaller pieces, while ___ processes change the mineral composition. | physical, bio-chemical |
The __ horizon is composed of organic materials generally above the mineral soil. | O |
The __ horizon is the topmost mineral horizon. Usually contains enough organic matter to give it a dark color. Often coarser textured due to loss of fine particles. Derive from dead plant and animal residues. | A |
The __ horizon is a zone of maximum leaching loss, eluviation of clay, Fe, and Al. Often sandy textured, below A horizon. Bleached, almost white color. | E |
The __ horizon is below O, A, or E horizon and has undergone sufficient pedogenesis such that the original parent material is no longer discernable. Often a zone of illuviation, accumulating clays, Fe, Al. | B |
The __ horizon is unconsolidated material underlying the solum (A and B horizons) | C |
5 Factors that influence soil formation | parent materials, climate, biota, topography, time |
___ is parent material transported and deposited by streams and rivers and deposited in floodplains, alluvial fans, and deltas. | alluvial |
__ is parent material that is transported and deposited by gravity. | Colluvial |
__ is parent material that is transported and deposited by ice. | Glacial till |
___ is parent material carried by rivers and streams and deposited in marine environments. | marine |
___ deposit occurred when glacial outwash was impounded allowing stratified sedimentation ranging from coarse beach sands to fine clay deposits | lacustrine |
___ ___ coarse sands and gravel deposited by glacial meltwater in an outwash plain | glacial outwash |
___ - parent material transported by wind. | eolian |
___ have the lowest degree of weathering and soil development and __ have the highest degree. | entisols, oxisols |
Usually the only genetic horizon is an A horizon, Characterized by great diversity in environmental setting and land use Many are found in steep, rocky settings, Those found on fluvial and alluvial material can be fertile and productive | entisols |
___ have minimum horizon development, widely distributed throughout the world, can be highly productive or of low productivity. | inceptisols |
___ are formed in volcanish ash or other volcanic ejecta, high water holding capacity, cover significant forest land in Pacific Northwest. | Andisols |
___ are soils of very cold climates that contain permafrost, limited to polar regions and high mountain elevations | gelisols |
__ are composed mainly of organic materials, contain at least 20-30% organic matter | Histosols |
___ are dry soils found in desert regions | Aridisols |
___ are clay rich soils that shrink and well with changes in moisture content, found where native vegetation is usually grasslands. | Vertisols |
__ are dark, soft soils of grassland ecosystems, characterized by a thick, dark surface horizon | mollisols |
__ are moderately leached forest soils with relatively high native ferility, develop under native deciduous forests | alfisols |
__ are strongly leached acid forest soils with low native ferility, found primarily in humid temperate and tropical regions on older, stable landscapes | ultisols |
___ form under coniferous forest vegetation and are characterized by a thin subsurface horizon with accumulation of humus complexed with Al and Fe - a spodic horizon | spodosols |
___ are very highly weathered soils found in humid tropical regions in stable landscape positions, native vegetation is rain forest | oxisols |
What are the three major factors that influence soil color? | organic matter content, water content, and presence and oxidation state of iron and manganese oxides. |
Soil colors are described using the __ color chart. | Munsell |
(Munsell color chart) hue: ___ , chroma: ___ , value: __ | hue: specific color , chroma: intensity or brightness of the color , value: lightness or darkness |
(Munsell color chart) 10YR 5/6 , 10YR is the __, 5 is the __ , 6 is the __ | hue, value, chroma |
The proportions of different sized individual mineral particles in soil determines the soil ___. | texture |
coarse textured soil is __ and has __ sand, __ clay | loose, more, less |
fine textured soil is __ and has __ clay, __ sand. | heavy, more, less |
loamy textured soil is an __ mix of sand, silt and clay | even |
___ is the major agent stimulating formation and stabilization of crumb type soil aggregates. | organic matter |
___ density is mass of solids/volume of solids | particle |
__ density is mass of solids/volume of soil | bulk |
soil compaction __ porosity and __ bulk density | decreases, increases |
__ is the attraction of water molecules to each other | cohesion |
__ is the attraction of water molecules to solid surfaces | adhesion |
__ results from greater attraction of water molecules for each other than for air. | surface tension |
water always moves from a __ to a __ energy state. | higher, lower |
___ force always pulls water from higher to lower elevation. | gravitational |
__ forces results from the attraction between water molecules and solid surfaces. Greatly reduce the energy state of water near soil particle surfaces | matric |
__ forces results from the attraction between water molecules and solutes. Reduces the energy state of water in the soil solution. | osmotic |
soil pores function like __ tubes. | capillary |
___ is saturated, o kPa | Maximum retentive capacity |
__ is when the macropores are filled with air, -10 to -30 kPa | field capacity |
__ is when macro, meso, and larger micropores are filled with air, -1500 kPa | permanent wilting point |
as you go from 0 kPa to -1500 kPa, remaining water is held with __ strength | increasing |
___ water content is Volume of water present per unit volume of dry soil | volumetric |
___ is Mass of water present per unit mass of dry soil | gravimetric |
___ flow is the movement of water through pores that are (completely) filled with water. Though all pores are filled with water, most movement is in larger, continuous pores. __ is the driving force. | saturated, gravity |
__ flow is far slower than __ flow. | unsaturated, saturated |
__ flow is water movement in soils when larger pores (macropores) are filled with air and micropores are filled with water. __ potential is the driving force. | unsaturated, matric |
__ is the entry of free water into the soil at the soil-atmosphere interface. | infiltration |
__ is the downward movement of water through the soil profile | percolation |
soil with __ porosity and __ of macropore space will have high rates of water infiltration and percolation. | high, a lot |
soil __ decreases water infiltration and percolation. | compaction |
as ___ content of soils increases, the soil water holding capacity will increase. | organic matter |
__ moist soil has __ root to soil contact, while dry soil has __ root to soil contact. | good, poor |