1. Environmental science
Soil
Environmental science

2. Pre Test
What is the difference between Soil Profile and Soil Horizons? 01
Which horizon accumulates organics and clays by the movement of water. 02
What are 5 soil forming factors 03
What horizons are considered Master horizons 04

3. Soil is made of What? 45% Mineral – Clay, Sand, Silt
25% Air – Oxygen is vital for plant growth and certain microorganisms
25% Water – Depends on porosity and precipitation
5% Organic Matter
5% Organisms (burrowing animals, bacteria, fungi, protists)
10% Roots
85% Humus
Soil is made of What?
NRCS Soils

4. Soil Texture University of Illinois Soil Science Extension
Particle Size effects porosity of soil
Influences water holding capacity
Water availability for plants
Water film around particles cannot be accessed by plants
University of Illinois Soil Science Extension

5. Fun Fact
Soils actually have a negative charge specifically clays and organic matter 1
Nutrients needed by plants are positively charged. 2
This is what we call cation-exchange or on soil samples cation-exchange capacities (CEC) 3
University of Illinois Soil Science Extension 4

6. Sand Silt Clay Soil Texture
Lacks the capacity to hold water and nutrients
Sand
Increases water holding capacity
Silt
Smallest particle
Greatest water and nutrient retention
Clay
U of I Rangelands p. 31

7. Soil Structure Arrangement of soil particles Blocky Platy Granular
Prismatic
Columnar
Massive

8. Soil Structure Greatly effects the permeability of soil (water or air)
Permeable Least Permeable

9. Soil-Forming Processes
Additions – addition of organic or mineral
Organic matter
Wind blown matter
Rainfall adds Nitrogen and other soil particulates
Losses – Loss of organic or mineral
Deep Leaching
Surface loss
Translocations – movement within soil
Low rainfall areas causes saline/alkaline problems because of incomplete leaching
Transformations – mineral or organic modification
Organic matter to humus by microorganisms
Chemical weathering of parent material (Fe -->Fe203)
file:///Users/Katy2/Downloads/surdown.pdf

10. Soil Forming Factors Weathering of minerals i.e. parent material
Climate
Biota (living plants/animals and the decomposition of organic matter)
Typography
Time
Soil and Our Environment p , Text p. 292

11. Weathering Breakdown of parent material in soil formation by physical and chemical breakdown
Mechanical Weathering
Freezing and Thawing (ice expansion)
Uneven Heating
Abrasion – ice, water and wind
Shrinking Swelling
Root activity
(Cornell University)
Chemical Weathering
Oxidation
Hydrolysis
Acidic rain

12. Climate Dry, cold climates Warm wet climates Slower Soil Formation
Slower weathering (depending on parent material)
Slower decomposition
Warm wet climates
Faster weathering (depending on parent material)
Faster decomposition
Text, p. 292
Slower Soil Formation
Faster Soil Formation

13. Biota Interaction of soil organisms such as plants, animals, microbes
Burrowing animals (gophers, earthworms, ants, etc.)
help mix nutrients
Plant Roots
some can reinstate soil nutrients
Breakdown parent material
Microorganisms (bacteria, fungi, protists)
Decompose organic matter
Text p 292, Soils and Our Environment p. 20

14. Typography The lay of the land (climate has an effect) Steep hillsides
Developing soil profiles
Nutrients are unable to be leached to lower horizons
Aspect – SW slopes receive more sun causing dry/arid
Rolling Hills
Deep soil profiles because water leaches materials to lower horizons
Good A,O Horizons
Valleys or Depressions
Rich organic soils
Salt marshes
Soils in Our Environment p. 22, Text 297

15. Time It takes a minimum of 1 year to develop 1” of top soil
Depends on Climate, Parent Material, Organisms, Topography
Effects the amount of time the soil is formed.
NRCS Soil Formation