ISA Board Certified Master Arborist (BCMA) — Practice Exam
Soils: practice questions
Our ISA Board Certified Master Arborist bank has 21 questions on this topic. Here are 5 of them with answers; the full mock exam draws from every topic, like the real one.
Question 1
Above what soil pH does the USDA Forest Service say to plant trees that do best on neutral to alkaline soils?
- 7.2
- 5.0, which is where most urban soils start to turn alkaline
- 6.0
- 9.5
Show the answer
A. 7.2 — Examples: hackberry, basswood, ginkgo and most crabapples.
Question 2
In the USDA Forest Service spade test, what does it mean if a shovel easily goes in two blade lengths?
- The soil is too wet to plant and needs drainage first
- Compaction is severe
- Compaction is not limiting
- The soil is pure sand
Show the answer
C. Compaction is not limiting — Needing to jump on the shovel means compaction may limit some species; needing a pick-axe means severe limits.
Question 3
In the USDA Forest Service percolation test, which result means the soil suits most tree species?
- A 24-inch hole, refilled, drains completely within 24 hours
- The hole drains within a couple of minutes on the second fill
- The hole takes several days to drain
- The hole never drains
Show the answer
A. A 24-inch hole, refilled, drains completely within 24 hours — Very fast drainage calls for drought-tolerant species; very slow for wet-site species.
Question 4
Why do trees that tolerate wet sites often do better than others in compacted clay?
- Wet-site trees have deeper taproots that break through compaction
- Clay holds less water
- Compaction adds nutrients
- Both conditions limit oxygen in the root zone
Show the answer
D. Both conditions limit oxygen in the root zone — USDA Forest Service species selection guidance.
Question 5
How does mulch improve soil over time, per ISA?
- It seals the soil surface so no water can evaporate or enter
- It seals the soil surface, keeping out rain while holding the existing moisture in place
- It improves soil biology, aeration, structure and drainage, and adds fertility as it decomposes
- It has no effect on soil
Show the answer
C. It improves soil biology, aeration, structure and drainage, and adds fertility as it decomposes — Inorganic mulch does not improve soil structure or add nutrients.