Ooooh Exciting Soil Soil is from parent rock It takes 200 years to form a layer of soil 1cm thick Soil forms distinct layers over time Layers can be distinguished by color texture and composition ID: 598984
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Slide1
Soil and Permafrost
Ooooh
! Exciting
Slide2
Soil
Soil is from
parent
rock
It takes 200 years to form a layer of soil...
1cm
thick!
Soil forms distinct layers over time.
Layers can be distinguished by color, texture and composition
The layers are called HORIZONSSlide3
O horizon – Organic Matter
Topmost layer
High % of dead organic matter.
Ie
: leaves, stems, fruits, seeds, pine needles
Formed from decomposition of organic matter. (humus)Slide4
A horizon - Topsoil
Seeds
germinate and plant roots grow in this dark-
colored
layer.
It is made up of humus (decomposed organic matter) mixed with mineral particles.Mixture of soil from below and
the humus above.Slide5
B horizon - Subsoil
Trees with deep roots draw nutrients from this layer
It is made up mostly of sand and silt, having lost most of its minerals and clay as water drips through the soil.
Leached from layers
above
Clay
and many minerals
Iron
Aluminum
CalciumSlide6
C horizon – Fragmented Parent Rock
Can
be saturated in
groundwater
Formed
through the disintegration of the underlying parent rock. It consists of slightly broken-up bedrock.Slide7
R Horizon – Unaltered Parent Rock
Plant roots do not penetrate into this layer. Starting point for soil
formationSlide8
Soil Conditions
Three conditions must be met for soil to be suitable for plant life to form:
Water soluble nutrients
Adequate moisture
Appropriate soil pH
Soil to acidic or alkaline jeopardizes the transfer of mineral nutrientsSlide9
Permafrost
Ground whose temperature has been
0
o
or lower for at least two years. Slide10
Permafrost
The upper layer thaws in the summer and some growing occurs, this layer is the
active layer
Permafrost makes construction difficult and agriculture nearly impossible
Inuit people build their homes on piles that pass through the active layer and sit directly on the permafrostSlide11
Texture and pHSlide12
Soil Texture
Soil texture is the single most important physical property of the soil. Knowing the soil texture alone will provide information about:
1) water flow potential,
2) water holding capacity,
3) fertility potential,
4) suitability for many urban uses like bearing capacitySlide13
To determine texture
The Percent of sand, silt, clay in a soil sample
Critical for understanding soil behavior and management
Soil texture is not subject to change in the field but can be changed in potting mixes.Slide14
Buffering Capacity
pH is measured on a scale of 0 (very acidic)-14(very alkaline)
Soil should ideally be between 6-7 to allow for maximum nutrient absorption
Soil has the ability to resist pH changes, when acidic or alkaline compounds are added this is it`s
BUFFERING CAPACITY