Landscape Design Soil Science and Site Preparation 2 — Questions and Answers
Question 1: What is the primary purpose of adding lime to landscape soil?
- Raise soil pH to make it less acidic (Correct answer)
- Lower soil pH to make it more acidic
- Add nitrogen to improve fertility
- Improve soil drainage
Correct answer: Raise soil pH to make it less acidic
Agricultural lime neutralizes soil acidity by raising pH, making nutrients more available for plants that prefer neutral to slightly alkaline conditions.
Question 2: What does a percolation test measure in landscape site assessment?
- Rate at which water drains through soil (Correct answer)
- Soil fertility and nutrient content
- Depth to hardpan or bedrock
- Soil compaction resistance
Correct answer: Rate at which water drains through soil
A percolation test measures how quickly water drains through soil by timing the drop in water level in a test hole, which is critical for drainage and irrigation design.
Question 3: What is the recommended depth of topsoil for establishing a new lawn from seed in the US?
- 4 to 6 inches (Correct answer)
- 1 inch
- 12 inches
- 2 inches
Correct answer: 4 to 6 inches
A minimum of 4 to 6 inches of quality topsoil provides adequate depth for turf root development, nutrient reserves, and soil moisture retention.
Question 4: What is hardpan and how does it affect landscape design decisions?
- Impermeable compacted soil layer that blocks drainage and root growth (Correct answer)
- Hard surface layer of mulch that repels water
- Rocky subsoil that requires blasting
- Compacted gravel base for hardscaping
Correct answer: Impermeable compacted soil layer that blocks drainage and root growth
Hardpan is a dense, impermeable soil layer that blocks drainage and root penetration, requiring raised beds, drainage solutions, or breaking through.
Question 5: Which nutrient deficiency causes yellowing between leaf veins (interveinal chlorosis) in landscape plants?
- Iron deficiency (Correct answer)
- Nitrogen deficiency
- Phosphorus deficiency
- Potassium deficiency
Correct answer: Iron deficiency
Iron chlorosis causes yellowing between veins while veins remain green; it commonly occurs in high-pH soils where iron becomes unavailable despite being present.
Question 6: What is the correct method for taking a representative soil sample for laboratory testing?
- Collect 10 to 15 cores from random locations and mix thoroughly (Correct answer)
- Take one deep core from the center of the area
- Sample only from areas where plants are struggling
- Collect surface soil from the top 1 inch only
Correct answer: Collect 10 to 15 cores from random locations and mix thoroughly
A composite soil sample made from 10 to 15 randomly collected cores mixed together accurately represents the overall soil conditions across an entire landscape area.
Landscape Design Soil Science and Site Preparation 2
What is the primary purpose of adding lime to landscape soil?