lecture 6 Flashcards
Soils
2 concept of soil?
Pedological concept and Edaphological concept
A natural body differentiated into horizon of mineral and organic constituent, consolidated of variable depth. Differs from the parent material below in morphology, physical properties and constitution
Pedological concept
A natural body, synthesized in profile form from a variable mixture of broken and weathered minerals and decaying organic matters, which covers the earth in a thin layer and which supplies when containing the proper amounts of air and water, mechanical support and in part sustenance for plants
Edaphological concept
Functions of soils
media for plant growth
modify the atmosphere through emission and absorption of gases
Habitat for animals that live in the soil
process recycled nutrients
Mineral horizon, finer textured, usually clayey with blocky structure
zone of maximum illuviation (movement of materials - Clay and AI oxides into the horizon
B horizon
Reffered to as the parent material, blocky to primatic structure, hard and sometime brittle but can still be dug by digging tools
C HORIZON
d
dense unconsolidated materials/physical root rstric
co
coprogenous earth
i
Organic matter, slightly decomposed
j
Jarosite
jj
Cryoturbation
k
accumulation of carbonates
kk
engulfment of horizon by secondary carbonates
m
cementation or induration
ma
marl
n
accumulation of sodium
o
accumulation of Fe and AI oxides
P
plowing
q
accumulation of silica
r
weathered os soft bedrock
solum
horizon a and b
regolith
horizon a, e, b and c
0 to 20 cm depth (plow layer)
top soil
soil beneath the topsoil (below20 cm depth)
subsoil
how soil formed
addition, transformation, transfer, losses
factors of soil formation
Climate, Organisms, Relief, Parent material and Time
Temperature and rainfall are the most critical both affect the rate of soil processes weathering and decomposition, also impacts the type of vegetation in area
climate
includes plants and animals from micro to macro: Grassland vs. forest vegetation, alter physical properties of soil like pore spaces
organism
Includes elevation, slope, aspect or exposure, affects stability of land surface for other soil-forming factors and processes to initiate and continue soil formationm
relief
has a great influence on the resulting property of the soil
Parent material
Types of parent material
A. Sedentary
Rocks - Igneous/ Sedimentary/ Metamorphic
B. Transported
Gravity - Colluvium
Water - Alluvium (river),
Ice - Glacial
Wind
determines the duration the parent material was subjected to the other soil-forming factors, the longer the time, under stable conditions, the more developed and old the soil,
time
