Test 1 Flashcards
Any foul substance such as mud and grime, dust ,excrement
Dirt
unconsolidated mineral and organic materials on the immediate surface of the earth that serve as a natural medium for the growth of plants.
Soil
Define Pediology
the study of soil a natural body.
Define Edaphology
study of soil from the standpoint of higher plants.
funcitons of soils(6)
- medium for plant growth
- recycling system for nutrients and organic matter.
- Habitat for soil organisms.
- Water supply and purification.
- Engineering Medium.
- Modifier of the Atmosphere.
top 1 to 2 meters where plant growth occurs.
Solum
Unconsolidated material overlying rock
Regolith
arrangement of the soil particles.
Soil Structure.
Red soil Indicates
dehydrated iron compounds
Yellow Soil indicates
hydrated iron oxides, somewhat restricted drainage.
Gray
reduced iron and poor drainage.
What typically produce soil colors?(4)
organic matter,iron compounds, silica and lime
Soil color indicates what (4)
organic matter, drainage, salts, and weathering
Surface soils are generally darker than subsoil due to higher concentration of organic matter contents, (True or False)
True.
dominant color of the rainbow
Hue
degree of lightness or darkness
Value
degree of purity of hue.(departure from grayness)
Chroma
Soil Texture influences(4)
water intake, absorption, soil aeration, and the nutrient holding capacity.
Sand particle size
.05-2mm
Silt particle size
.002-.05mm
Clay particle size
less than .002mm
Anything under 2mm in size
Soil particle
the arrangement of soil sparates into aggregates called peds.
Structure
(type of structure)Soil surface affected by tillate
Granular
(type of structure) very porous granular
crumb
(type of structure) anything flat
platy
(type of structure) angular or subangular
Blocky
(type of structure) single grained
structure less.
A vertical section of the soil through all of its horizons, extending surface to the parent material.
Profile
horizontal soil layer that differs in characteristics from layers above and below.
Horizon
(Master Horizon) above the surface of the mineral soil
O, Organic horizon
(Master Horizon) enriched with organic matter.
A, Surface mineral
(Master Horizon) zone of loss. Loss of silicate clay, Fe and Al leaving a concentration of resistant sand of silt particles.
E, Eluvial horizon
(Master Horizon) zone of accumulation, accumulation of Fe and clay that results in enhanced structure.
B, illuvial horizon.
(Master Horizon) material little affected by soil forming.
C, Parent Material
(Master Horizon) like sandstone, limestone, or granite.
R, Hard Bedrock
subordinate (g)
soil is grey due to poor drainage.
subordinate (p)
plowing or other disturbance
subordinate (t)
accumulation of silicate clay
subordinate (x)
fragipan, high bulk density.
the chemical breakdown of rocks and minerals with the formation (synthesis) of new minerals.
Weathering
weathering produces
plant materials for soils.
Types of physical weathering
Abrasion, Organisms, Temperature, Physical disintegration.
Main agents of chemical weathering
Water, oxygen, carbon dioxide.
Five reactants involved in decomposition
Solution, hydrolysis, carbonation, oxidation, hydration.
Solution
dissolving a solid in a liquid
Hydrolysis
Attack of H+ ions onto crystal surfaces spliting of H20 molecules .
Carbonation
Reaction of compound with carbonic acid formed by root and organism respiration.
Oxidation
Loss of electrons, transfer of electron reactions.
Hydration
Combination of water with a solid chemical mineral or salt
topography mostly affects: (2)
Soil moisture and relationships, Soil Erosion
Climate mainly affects:
moisture and temperatue
Precipitation does what:
increases weathering and clay formation,
decreases pH and Lower fertility
Increases vegetation and organic matter.
Temperature affects
10C doubles rates of reaction, affects organic matter content in soils(moisture).
Prairies vs. Forests
Prarie has more organic matter and its more evenly distributed.
How does time affect soil development
in a warm humid climate soil development is much faster than in an arid region.
Classification system of Soils
Soil taxonomy
(Surface Horizons) Mollic
thick dark colored, high fertility
(Surface Horizons) Umbric
thick dark colored, low fert.
(Surface Horizons) Orchric
light in color, low organic matter, hard
(Surface Horizons) Histic
very high organic
(Subsurface Horizons) Argillic(t)
silicate clay
(Subsurface Horizons) Fragipan (x)
brittle pan dense loamy
(Subsurface Horizons) Albic(E)
light colored, clay Fe
(Subsurface Horizons) Cambic (w)
altered or changed by
Collection of soil seperates held together by clay organic matter and other cementing agents. Important in inflitration and absorption.helps percolation and holds soil to the surface.
Aggregates
dispersion of soil particles and sealing the pores
Soil crusting
Particle Density (formula)
density of soils solids alone, (mass or dry soil)/(volume of solids)
Bulk Density (formula)
density of soil as it exists in nature.
mass of dry soil)/ (volume of solids + pores
the physical condition of the soil in relation to plant growth.
Soil Tilth
hydrogen bonding
low energy bond between H atom of one water.
attraction of water molecules for each other
Cohesion
Adhesion
Attraction of water molecules for solid surfaces
results from greater attraction of water molecules for each other than for air.
Surface Tension
the difference in energy level between pure water and soil water
Soil water potential
tendency of excess water to move to the water table
Gravitational potential
pressure potential
Matric potential(suction and tension)
Solute Potential
+ due to weight of
- attraction of water to solid surfaces
negative, osmotic potiential
Maximum Retention Capacity
saturation, all pores are filled with rain water.
Field Capacity
Rain water drains for 2 to 3 days
Permanent wilting Point
plants cannot obtain enough water from soil to survive.
hygroscopic water
moves through pores as water vapor, non liquid.
Capillary water
water moves in pores of capillary size, along potential gradient. between field capacity and hygroscopic water
Plant available water
water that can be absorbed by roots.
measures potential by which water is held in soil
Tensiometer
Five soil forming factors
Climate, Native, Parent, Topography, Time
Soil Genesis
the evolution of soil from its parent material.
parent material
the upper part of the regolith that develops into a soil.
Minerals
Solid, inorganic elements or elemental compounds having definite atomic structures and chemical compounds which vary within a fixed range.
Rocks are _____
aggregates of minerals
——-parent materials are formed in place from rocks and minerals
Residual or residum
_______form from molten magma, kind of minerals found in igneous rocks.
Primary minerals
_______ are recrystallized products of the chemical breakdown of primary minerals.
Secondary Minerals
________ rocks, high temperature melts that solidify into minerals upon cooling.
Igneous
________rocks, formed from the products of mineral weathering that are created in one location and then transported and deposited in another (usually the ocean floor)
Sedimentary
______result from the transformation of igneous or sedimentary rocks under high heat and pressure.
Metamorphic
Parent materials transported by gravity
Colluvium
Parent materials transported by water(3)
Alluvium, Marine, Lacustrine
Parent materials transported by wind
Eolian
parent materials transported by ICE
Glacial
6 levels of classification from biggest to smallest.
order, suborder, great group, subgroup, family, series
formed from volcanic ash and lava deposits
Andisols
Soils with argillic or natric horizons; formed under forests
Alfisols
have a permafrost layer
Gelisols
young soils with weak B horizons
inceptisols
mostly highly weathered soils; accumulation of Fe and Al oxides
Oxisols
very young soils with no B horizon
entisols
Formed in dry Climates
Aridisols
High content of shrink-swell clays; deep cracks when dry
Vertisols
Soils with more than 30% organic matter
histosols
Soils with deep, Dark A horizons formed under grasslands
Mollisols
Have a spodic horizon
Spodosols
more weathered than alfisols but less weathered than oxisols
Ultisols
