1. Soil Structures

2. A. Explain the nature and composition of soil;
Soil is the outer layer of the earth
Dirt is displaced Soil
Composition of average soil
a. 25% Air
b. 25% Water
c. 5% Organic Matter
d. 45% Mineral Matter
4. Pore Space: Spaces between solid matter, air and water will fill pore spaces

3. B. Describe how soil is formed, and define terms of formation;
Begins when Parent Material or Rock is weathered
Weathering: process when the climate breaks rock into small pieces (4 Factors)
Freeze and Thaw
Rainfall
Wind
Water
3. River and Glacial Sediments (soil particles)
Alluvial Soil: soil deposits left by rivers and oceans
Glacial Soil: soil created, moved, and deposited by glaciers

4. 4. Living Organisms a. Plants: roots break apart rocks, lichens produce acids b. Animals: earthworms, insects, bacteria and fungi

5. Biological Properties
The Soil Ecosystem
Interaction of biotic and abiotic factors in a soil environment. The process of organisms growing and decomposing.

6. C. List and define mineral components of soil;
Mineral Matter: inorganic material, non-living
Particles are labeled as Sand, Silt and Clay
a.Sand: largest particle
Large pore space, good aeration
Well drained
Not fertile, in able to hold nutrients
Feels gritty
b. Silt: mid sized particle
Good water holding capacity
Retains nutrients
Feels like flour dry, velvet wet

7. c. Clay: Smallest particle
Ability to hold water and nutrients
Small pores, poor aeration and drainage
Hard clumps when dry, feels sticky when wet

8. D. Discuss soil texture and the textural triangle;
Soil Texture: determined by proportions of the three types of mineral particles
a. Each Soil type has a name
b. Example: 40% sand, 20% clay, 40% silt, loam soil
2. Common Soil types
a. Sandy Soil: Looseness, well aerated, good for root crops
b. Silty loam Soil: Very fertile, good to grow in.
c. Clay Soil: Heavy, dries very hard.

9. 3. Textural Triangle: uses percentages of particles to determine soil types. Example: 40% Sand 20% Clay 40% Silt

10. Practice 40% sand 22% clay and 38% silt
What is the soil classified as?

11. Practice
90% sand 10 % clay and 25 % silt
What is it?

12. Practice
30% sand 50 % clay and 20% silt
What is it?

13. Soil Texturing Ribbon Method Soil Sedimentation Method
See if you can make a ribbon and with which one?
Which one feels grittiest?
Which one feel powdery?
Soil Sedimentation Method
Place soil in a jar
Mix soil and water
Let it settle

14. Time for a Lab
Before we begin put everything away (this could get a little dirty)
Pick up lab sheets
Soil Texture by Feel Answer Sheet
Soil Texture Flow Chart
You will need to texture each of the four samples of soil
Keep your area as clean as possible

15. F. Define Organic Matter and common soil amendments;
Organic Matter: the accumulation of decayed or partially decayed plants and animals.
Common additions of Organic matter to soil:
Manure, animal waste
Green “Manure”, or cover crop that is plowed in
Peat Moss or Compost, common for gardeners

16. G. Describe water relationships in the soil;
Three main types of ground water.
Gravitational Water: Free flowing water pulled down by gravity.
Flows quickly through sand, slowly through clay
Leaching: as water moves through soil it carries with it nutrients, salts and chemicals.
3. Capillary Water: held between particles, moves up and sideways through soil.
As soil dries out, it pulls water up though the pore space.
Plant available

17. 4. Hygroscopic Water: water held in a thin film around the individual soil particles
Not plant available

18. H. Describe the role of air in the soil;
Air should make up 25% of the soil sample
Air is in the pore space, fills with water after rain
Must have a balance between air and water to maintain most plant life
Too much water (lack of air), fermentation
Not enough water (too much air), wilted plants

19. Granular: most desirable
Explain soil structure;
1. Aggregates: large clusters of soil particles
2. Soil Structure: the way which aggregates are arranged (8 types of structures)
Granular: most desirable
Crumb: also desirable
Platy
Prismatic
Massive
Columnar
Blocky
Single grain

20. 8 Types of Structure

21. 2. Damage: Humans can destroy soil structure a
2. Damage: Humans can destroy soil structure a. Driving heavy equipment on when wet b. Working Soil when excessively wet 1) Clay particles clog pore spaces, soil compaction. 2) Poor drainage, plants cannot grow

22. J. Illustrate and label soil profiles;
Soil Profile: a view of a cross section of soil
a. Soil is arranges in layers called Horizons
b. Horizon: layers of soil in the profile
1) Five major horizons, all horizons have names
2) Depth and thickness of horizon vary depending on location

24. Soil Horizons 2. Main Horizons
a. O horizon- Litter Layer, Organic material
b. A horizon- Top Soil, most fertile, up to 10 inches deep
c. B horizon- Sub soil, some nutrients leached from above
d. C horizon- Weathered bedrock & some leached materials
e. R horizon- Bedrock, or solid rock, parent material

25. Erosion: the removal of soil by wind or water
K. Discuss the process of soil erosion, its importance, and prevention.
Erosion: the removal of soil by wind or water
Loosing valuable soil that then can pollute water and air
Soil Conservation
Agricultural practices: Strip cropping, terraces, no till
Wild land and home owners: plant roots can anchor soil in place

26. Erosion
No till planting
Terrace cropping