Unit 1 Lesson 5

Question 1

Soil

Answer 1

A loose mixture of small rock fragments, organic matter, water and air that can support the growth of vegetation

Question 2

What is the 1st step in soil formation?

Answer 2

The weathering of Parent Rock
Soil forms directly above parent rock

Question 3

Humus

Answer 3

Dark organic material formed in soil from the decayed remains of plants and animals

Found in the top layer of soil. Contains nutrients that plants need to grow

Question 4

Soil profile

Answer 4

A vertical section of soil that shows all of the different layers

Question 5

Soil Horizon

Answer 5

Each layer of soil that has different physical properties

A Horizon - topsoil. Dark color. Has the most humus
B Horizon - has a reddish or brownish color from minerals and clay
C Horizon - largest rock fragments. No organic matter

Question 6

What factors determine how long it takes for soils to form?

Answer 6

1. Rock type - certain rock types weather at different rates
2. Climate - soil develops more quickly in warm, wet areas than in cold, dry areas
3. Topography (flat vs steep) - soil is eroded faster on steep slopes. Develops faster on flat areas
4. Plants and animals - plant roots hold sediment in place allow soil to develop quickly
   areas with animals have higher rates of decomposition. Soil develops quickly

Question 7

Decomposer

Answer 7

Animals that break down dead organisms and return their nutrition to the soil

Examples: earthworms, groundhogs, moles, bacteria, fungus

Question 8

Soil texture

Answer 8

Describes the relative amounts of different sized soil particles

Sand. - largest particle. Feels coarse or rough
Silt - smooth and silky feel
Clay - smallest particle. Smooth and stickly

Question 9

Tropical Soil

Answer 9

Form in warm, wet regions
Thin layer of humus
Soil development is fast. Not good for crops

Question 10

Desert Soils

Answer 10

Form in dry regions
Shallow and contain little organic material
Soil development is slow

Question 11

Temperate Soils

Answer 11

Form in regions with moderate rainfall and temperature
Dark colored and rich in organic material and minerals
Best for crops

Question 12

Arctic Soils

Answer 12

Form in cold, dry regions
Do not have well- developed horizons
Contain many rock fragments

Question 13

Pore Space

Answer 13

Describes the spaces between soil particles
Water and air are found in the pore spaces
Soil with many (larger) pore spaces are good for plant growth

Question 14

Soil Fertility

Answer 14

Describes how well soil can support plant growth
Affected by:
Climate
Amount of humus, minerals, and nutrients
The topography ( flat vs steep)