Drill (Pre-Lab)• Soil Pre-Test: Take an “educated”

guess!– Based on your prior knowledge,

identify whether the following statements are True (T) or False (F).1. There is only one type of soil.2. Soil is permeable (allows water to move

through).3. Soil is biotic (living) factor.4. Plants need gravel to live.5. Soil has different sizes.

Are All Soil Particles the Same Size?

Field BiologyCarbon Career & Technical

InstituteMrs. Conway

Objective

• SWBAT identify the types and sizes of particles that make up soils, order soil components according to particles from the smallest to the largest, and investigate the effect water has on the soils IOT describe soil porosity.

Are All Soil Particles the Same Size?

• No!• Particles larger than 2mm in

diameter are not considered soil, but gravel or stones.

• Why not?• These particles do not have any

direct value to plants.

Are All Soil Particles the Same Size?

• Sand: Largest soil particles (0.05 to 2 mm in diameter )

• Silt: Medium sized particles (0.002 to 0.05 mm in diameter)

• Clay: Smallest particles (less than 0.002 mm in diameter)

Are you listening??

What is the largest soil particle?

Relative Soil Particle Sizes

So What is Loam?• Loam has an optimum combination

of different particle sizes.– 40% Sand– 40% Silt– 20% Clay– Loam is an ideal agricultural soil

because of this combination.• Larger particles provide structural support,

aeration, and permeability to the soil. The smaller particles bind together into clumps and hold nutrient minerals and water

Are you listening??

How is loam different from the

other types of soil?

Soil Porosity• The rate at which water will pass

through the soil.• A measure of the volume of pores or

spaces per volume of soil and of the average distances between these spaces.

• Soil needs to have some porosity for the roots to be able to get the required amount of oxygen.– If soil has particles of different sizes, then pore

spaces should be present because particles of different sizes together will leave gaps.

– Air and water can then get to the plant roots .

Soil Texture Triangle

Practice

• What is the name of a soil that is – 10% Silt,

60% Clay, and 30% Sand?

Exit Ticket

• When you build a sand castle, you obviously use sand. Why is this not the best “building material” to use? If you could make your castle out of any type of soil, what would you choose and why?

Drill (Lab)• What is the name of the soil that is: – 20% Sand,

20% Clay, and 60% Silt?

– 10% Sand, 80% Clay, and 10% Silt?

Pre-Lab Procedure

• Complete the concept map with the appropriate soil types and particle sizes.

• Read through your laboratory procedures.• Draw 3 pictures of each procedure listed

on page 615.• Use the soil texture triangle to

determine the soil compositions listed in the table.