Soil Physical PropertiesUnit 2.1 | 15
Students’ Lecture Outline
b) What causes structure?
i. Biological factors/organic matter
• Bacterial exudates
• Root activity and exudates
• Macrofauna activity and waste
ii. clay (type and amount)
iii. calcium and sodium effects
iv. Climate (wet/dry, freeze/thaw)
figUre 4. SOIL STRUCTURE ANd ITS EFFECTS ON PERMEABILITy
- Pores
a) What are they and why are they important?
Pores are the “holes” or voids in the soils. They are important because air and water move
through and are stored in pores. Without air, roots cannot live nor can most microbes
that are essential to the proper functioning of a healthy soil.
b) Types of pores: Three types of pores are generally recognized
i. Interstitial pores: Spaces between mineral grains and peds
ii. Tubular pores: Pores made by root or animal activity that are or were at one time continuous
iii. Vesicular pores: Bubble-shaped pores