Certified Arborist Test Soil Science and Root Management 2

Question 1

What is soil compaction and what is its primary effect on tree root development?

Accepted Answer

Increased bulk density that reduces pore space, limiting oxygen and root penetration

Answer

An increase in organic matter that restricts microbial activity

Answer

A decrease in clay content that reduces water retention capacity

Answer

An elevation in soil pH that locks up micronutrients

Question 2

What does cation exchange capacity (CEC) measure in soil, and why is it important for tree nutrition?

Accepted Answer

The soil's ability to hold and exchange positively charged nutrient ions

Answer

The rate at which water infiltrates through the soil profile

Answer

The total organic matter content as a percentage of dry soil weight

Answer

The buffering capacity of soil against sudden pH changes

Question 3

What is mycorrhizal symbiosis and how does it benefit trees?

Accepted Answer

A mutualistic association where fungi extend root absorption capacity in exchange for carbohydrates

Answer

A parasitic fungal infection that decomposes organic matter in the root zone

Answer

A bacterial colonization that fixes atmospheric nitrogen in root nodules

Answer

A protective coating on roots that prevents pathogen entry

Question 4

What is the difference between macropores and micropores in soil, and how do they affect tree root function?

Accepted Answer

Macropores drain quickly and hold air; micropores hold water available to plants

Answer

Macropores hold water for plant use; micropores drain rapidly and hold air

Answer

Macropores are created by earthworms only; micropores form from clay minerals

Answer

Macropores are found in surface soil; micropores are restricted to subsoil layers

Question 5

What are the symptoms and causes of iron chlorosis in trees growing in high-pH soils?

Accepted Answer

Yellowing of young leaves with green veins caused by iron being insoluble and unavailable at high pH

Answer

Dark green veins with brown interveinal tissue caused by iron toxicity from soil acidification

Answer

Uniform pale green coloration of all leaves due to excess calcium competing with iron

Answer

Purple discoloration of leaf margins caused by iron displacement of phosphorus

Question 6

What is the primary goal of vertical mulching for tree root zone improvement?

Accepted Answer

Creating aerated channels through compacted soil to improve gas exchange and root penetration

Answer

Preventing surface evaporation to conserve soil moisture in drought conditions

Answer

Introducing mycorrhizal inoculants deep into the soil profile where roots are active

Answer

Building raised berms to direct irrigation water toward the tree base