1. Environmental Science: Soil
5.03 Understand basic environmental science practices and principles

2. Soil World’s largest sponge Soil Profile A Horizon – top soil
B Horizon – subsoil
C Horizon – bedrock

3. Soil Profile A Horizon – topsoil
Surface layer of soil approximately 6” deep
Usually contains more organic matter than other horizons
Typically darker colored because or organic matter
Layer that has the greatest influence on crop production (plant growth)

4. Soil Profile B Horizon – subsoil Subsurface layer
Most subsoil has an increase in clay content
Layer that has the greatest influence on urban uses such as building sites, septic systems, ect.

5. Soil Profile C Horizon – parent material (bedrock)
Releases water to the upper soil layers
Contains larger soil particles including gravel and large rocks

6. Soil Texture Texture refers to the size of soil particles
Sand – largest soil particle
Sandy soils have problems holding enough water for good plant growth, but they do drain well
Individual particles can be seen with the naked eye
Silt – intermediate size soil particle that can’t be seen with the naked eye
Clay – smallest soil particle
Clayey soils hold lots of water but may be airtight, infertile for root growth, and associated with wet soils

7. Soil Texture

8. Soil Structure
Structure refers to the tendency of soil particles to cluster together and function as soil units called aggregates that leave pore space to store air, water, nutrients, and allow root penetration
Single grain – associated with sandy soils
Granular – particles cling together to form rounded aggregates
very desirable for all soil uses
Blocky – particles cling together in angular aggregates
Typical of soils with high clay content

9. Soil Classification
Land capability maps are based on the physical, chemical, and topographical aspects of the land

10. Soil Classification
Land capability classes are designated by Roman Numerals I – VIII
Class I and II land is the best land for the most intensive cultivation of field crops with the fewest limitations and can be planted year after year
Class VII land is very steeply sloping and best used for planting trees
Class VIII land is best suited for wildlife and recreation

11. Soil Conservation Two types of erosion
Sheet – removal of layers of soil from the land
Gully – removal of soil that leaves trenches
“No till” is a cropping technique used to reduce soil erosion
Crops are planted directly into the residue of a previous crop without plowing or disking
An effective means of erosion control

13. Soil Conservation
Conventional Tillage – uses tillage system that disturbs the soil surface by plowing, disking and/or harrowing
Conservation Tillage – intermediate tillage system conventional and no-till