ISA Soil Management 2

Question 1

Which soil texture has the highest water-holding capacity?

Accepted Answer

Clay

Answer

Clay soils have the highest water-holding capacity due to their large surface area and small pore spaces.

Question 2

What is the primary function of soil organic matter for tree health?

Accepted Answer

Improves nutrient retention and soil structure

Answer

Soil organic matter improves cation exchange capacity, water retention, and aggregation, all benefiting tree growth.

Question 3

Soil compaction most directly damages tree roots by:

Accepted Answer

Reducing macropore space and oxygen diffusion

Answer

Compaction destroys macropores, limiting the oxygen supply roots need for aerobic respiration.

Question 4

Vertical mulching is used primarily to:

Accepted Answer

Introduce air and organic matter into compacted soil

Answer

Vertical mulching involves drilling holes in compacted soil and filling them with compost or gravel to restore aeration.

Question 5

Which nutrient is most commonly deficient in high-pH (alkaline) soils?

Accepted Answer

Iron

Answer

Iron becomes insoluble at high pH, causing iron chlorosis characterized by interveinal yellowing on new leaves.

(ISA) ISA Certified Arborist Practice Test