ISA Soil Management 3

Question 1

A soil test reports a pH of 5.0. Which amendment would most effectively raise the pH?

Accepted Answer

Ground limestone (calcitic lime)

Answer

Calcitic lime (calcium carbonate) neutralizes soil acidity and raises pH, making nutrients more available.

Question 2

Which soil horizon is typically richest in organic matter and most important for tree root activity?

Accepted Answer

A horizon

Answer

The A horizon (topsoil) contains the highest concentration of organic matter and supports the most active root zone.

Question 3

Nitrogen deficiency in trees typically presents as:

Accepted Answer

Uniform yellowing of older leaves first

Answer

Nitrogen is mobile in the plant, so deficiency symptoms appear first on older leaves as nitrogen is redirected to new growth.

Question 4

What is the recommended depth for applying organic mulch around trees?

Accepted Answer

2–4 inches

Answer

A 2–4 inch mulch layer conserves moisture and moderates temperature without creating anaerobic conditions at the root flare.

Question 5

Which soil type is most prone to waterlogging and anaerobic conditions?

Accepted Answer

Clay soil

Answer

Clay soil's fine particles create micropores that drain very slowly, leading to persistent waterlogged, oxygen-poor conditions.

(ISA) ISA Certified Arborist Practice Test