soil: a renewable resource pa standards 3.1.12.c: unifying themes 3.7.12.b: technological devices ...
TRANSCRIPT
Soil: A Renewable Resource PA Standards
3.1.12.C: Unifying Themes 3.7.12.B: Technological Devices 4.6.12.C: Ecosystems and their
Interactions
“Land, then, is not merely soil; it is a fountain of energy flowing through a circuit of soils, plants, and animals.”- Aldo Leopold, A Sand County Almanac, 1949
Evaluate change in natural systems.
Analyze how natural changes affect the balance within an ecosystem.
Assess and apply recurring patterns in natural systems.
Evaluate appropriate instruments and apparatus to accurately measure materials and processes.
Key Questions
What are soils and how are they formed? What happens to matter in an ecosystem? What are the soil horizons and how do
they indicate the principal soil type? What are the different properties of soil?
Importance of Soil What is Soil?
Soil is a thin covering over most land that is a complex mixture of eroded rock, mineral nutrients, decaying organic matter, water, air, and billions of living organisms (microscopic decomposers)
Why is it important? Base of life on land. Provides most of the nutrients needed for plant growth
and also helps purify percolating water and store water. Helps decompose and recycle biodegradable wastes. Stores carbon as carbon compounds.
Soil as a Resource
How does it form? Bedrock broken down into rock fragments and
particles by physical, chemical, and biological processes called weathering.
Lichens add nutrients and when they die add organic matter
Renewable resourceVery slowly – 1 cm (0.4 inch) of soil can take
from 15 to hundreds of years to formMature soils, or soils that have developed over a
long time, are arranged in a series of horizontal layers called soil horizons.
Layers in Mature Soils Infiltration
The downward movement of water through soil.
LeachingDissolving of minerals and organic matter in
upper layers carrying them to lower layers. The soil type determines the degree of
infiltration and leaching.
Some Soil Properties
Soils vary in the size of the particles they contain, the amount of space between these particles, and how rapidly water flows through them.
Porosity: the amount of empty pore space in the soil
Permeability: the ability of a soil sample to transmit fluid
Sand has high porosity and high permeability
© Brooks/Cole Publishing Company / ITP
Fig. 5–17
Soil texture is determined by the particular mix of clay, silt, & sand.
Who Am I?
5% clay, 15% silt, 80% sand
Loamy sand
40% silt, 35% clay, 25% sand
Clay loam
9% sand, 85% silt, 6% clay
Silt
16% sand, 55% silt, 29% clay
Silty clay loam
Try these…
% Sand % Silt % Clay Texture Classification
30 20 50
50 20 30
40 40 20
10 60 30
30 40 30
60 30 10
10 45 45
How did you do?
% Sand % Silt % Clay Texture Classification
30 20 50 Clay
50 20 30 Sandy Clay Loam
40 40 20 Loam
10 60 30 Silty Clay Loam
30 40 30 Clay Loam
60 30 10 Sandy Loam
10 45 45 Silty Clay
Activity
Soil Texture Analysis ActivityTexture by FeelTexture by Sedimentation
Soil Texture Triangle
Review Key Questions
What are soils and how are they formed? What happens to matter in an ecosystem? What are the soil horizons and how do
they indicate the principal soil type? What are the different properties of soil?
Thought Problems What type of soil would produce high crop yields? What
type of terrestrial types (biomes) are these found?
Why is the humus beneficial?
What layers of soil are the roots of most plants and the majority of a soil’s organic matter concentrated?
What color soil would be good for growing crops?
Which layers have the most amount of inorganic matter?
Is a more or less porous soil better for plant growth?
Thought Problems - Answers What type of soil would produce high crop yields? What type of terrestrial types
(biomes) are these found? Fertile soil with thick topsoil layer with lots of humus. They are found in grasslands or
deciduous forests. Why is the humus beneficial?
It helps the topsoil hold water and nutrients taken up by plant roots. What layers of soil are the roots of most plants and the majority of a soil’s organic
matter concentrated? The top two layers.
What color soil would be good for growing crops? Dark brown or black – rich in nitrogen and organic matter. Gray, bright yellow, and red
topsoil's have low organic matter and nitrogen. Which layers have the most amount of inorganic matter?
The B horizon (subsoil) and C horizon (parent material). Is a more or less porous soil better for plant growth?
More porous – it contains oxygen, necessary for cellular respiration, and nitrogen gas.