Week 1 - Topic 2 - Soil Texture

Question 1

What is Soil Texture?

Answer 1

Describes the relative proportions of sand, silt, and clay particles in soil

Important for determining water and nutrient holding capacity, soil aeration, drainage characteristics, workability, and susceptibility to compaction.

Question 2

What are the sizes of soil particles?

Answer 2

• Sand (0.02 - 2.0mm)
• Silt (0.002 - 0.02mm)
• Clay (<0.002mm)

Sand is similar to beach sand, silt to talcum powder, and clay consists of small particles that stick together like modeling clay.

Question 3

What are the advantages and disadvantages of Sands?

Answer 3

• Advantages: Good drainage, good aeration, easy to dig, not sticky
• Disadvantages: Low water holding capacity, leaches nutrients, poorly structured

Sands are classified as coarse textured.

Question 4

What are the advantages and disadvantages of Clays?

Answer 4

• Advantages: High water/nutrient holding, well structured
• Disadvantages: Prone to waterlogging, reactive, slow air/water movement, hard to dig, compacts easily

Clays are classified as fine textured.

Question 5

What are the characteristics of Loams?

Answer 5

Considered ideal soil mix with balanced properties between sand and clay

Loams are classified as mixed texture and are rare in Sydney.

Question 6

What does the Texture Class Naming Convention indicate?

Answer 6

Last word indicates the main texture class; first word is descriptive of characteristics

Examples include ‘Sandy loam’ and ‘Loamy sand’.

Question 7

What are the methods to determine soil texture?

Answer 7

• Particle size analysis (Laboratory method)
• Field texture assessment
• Settling method

These methods help in accurately assessing soil texture.

Question 8

What are the steps in Field Texture Assessment?

Answer 8

• Remove grit/stones
• Wet the soil sample
• Knead it thoroughly
• Form a ball/bolus/sausage
• Observe texture characteristics
• Make a ribbon
• Compare to texture assessment chart

The texture characteristics can indicate sandy, clayey, loamy, or silty soils.

Question 9

True or False: Changing soil texture is generally easy.

Answer 9

False

It is generally difficult to change soil texture due to mixing challenges.

Question 10

Fill in the blank: Adding _______ can improve drainage.

Answer 10

sand

Small area modifications can be done to improve soil characteristics.

Question 11

Fill in the blank: Adding _______ can improve water holding capacity.

Answer 11

loam

Loam is easier to mix with other soils than clay.