1. Physical Properties of Soil
Topic 2052
Developed by Amanda R. Moore

2. Overview
Soil Composition
Parent Material
Physical Properties

3. Soil Composition Mineral and Organic Matter Soil Organisms
increase soil productivity because of decomposition of organic matter by the organisms
Water and Air

4. Parent Material
Definition: The un-weathered material from which a soil is formed
“The stuff you start with!”

5. Parent Material How does it affect the soil?
Soils resemble their parent material
Parent material can influence soil texture, mineral composition and layering
Has an indirect affect on natural vegetation
What grows depends on chemical and mineral composition of soil
The degree of layering of a soil can influence the properties and uses of a soil

6. Soils originating from different parent materials
Bolivia
Florida Michigan

7. Physical Properties of Soil
Texture
Structure
Consistence
Porosity
Density
Color
Temperature

8. Texture
Definition: The relative proportion of sand, silt and clay(different size particles) found in soil
“The fineness or coarseness of soil”
3 Separates
Sand
Silt
Clay

9. Texture Soil Separates Sand
Ranges from very coarse(2.00mm) to very fine(0.05mm)
Has a gritty feeling, does not stick together
The presence of sand increases size of space between particles
Facilitates movement of air and water

10. Texture Soil Separates Silt
Very smooth and flour-like
Particle sizes between 0.05mm & mm
Forms clods that crumble easily when wet
Water soaks in and moisture holds well
Soils with the larges water holding capacity for plant growth are high in silt

11. Texture Soil Separates Clay
Particles are very fine – 0.002mm and smaller
Appear “platey”, fit very close together
Stick together, difficult to break when dry
Amount of clay in soil has a great influence on water-holding capacity
Are negatively charged and attract plant nutrients

12. Soil Structures Blocky Granular Platy
Blocky Granular Platy

13. Structure
Definition: Arrangement of primary soil particles into secondary particles
Influences soil by increasing the average size of pores in the soil
Structure is not permanent
Platy, prismatic, columnar, blocky, crumbly, granular and structureless

14. Soil Consistence
Definition: The resistance of soil to deformation or rupture.
Deals with the strength and nature of the forces between soil particles
Basically, “how well does it stick together?”

15. Pore Space/Porosity
Pore space is the volume or amount of space within a soil that is not occupied by particles of mineral and/or organic matter
Texture, structure and compaction affect amount of pore space

16. Density
The specific gravity of soil particles is 2.6g/cm3 This is the particle density of soil particles
A soil that has no spaces between the particles would weigh 2.6 g/cm3 (160lbs/ft3)
Particle density is the average density of the soil particles.

17. Density
Bulk density is the weight of soil/unit volume of soil, including pore space.
As bulk density increases, the amount of pore space decreases
The maximum bulk density would equal particle density
Low bulk density=loose soil
High bulk density=compaction

18. Color An indirect measure of other important characteristics
Water drainage
Aeration
Organic matter content
Colors are determined by matching the color of sample with color chips in a soil-color book

19. Temperature Affects nutrient and water movement
Chemical processes are temperature dependant
Cold soil temperature can inhibit elongation of roots
Alternate freezing and thawing affects structure formation