CFB Soil Science & Amendments 1 — Questions and Answers
Question 1: What sand particle size range does the USGA recommend for sports field root zones?
- 0.05–0.125 mm (very fine sand)
- 0.25–1.0 mm (medium to coarse sand) (Correct answer)
- 1.0–2.0 mm (very coarse sand)
- 2.0–4.0 mm (fine gravel)
Correct answer: 0.25–1.0 mm (medium to coarse sand)
USGA specifications recommend sand predominantly in the 0.25–1.0 mm range to balance adequate drainage with structural stability.
Question 2: Which soil texture classification is generally considered most problematic for natural grass sports fields without significant amendment?
- Sandy loam
- Loam
- Clay (Correct answer)
- Silt loam
Correct answer: Clay
Clay soils have poor drainage, high compaction potential, and become very slippery when wet, making them the most problematic for sports fields.
Question 3: What does the Standard Proctor Test determine?
- Soil pH and lime requirement
- Soil permeability rate
- Maximum dry density and optimum moisture content for compaction (Correct answer)
- Organic matter percentage in the soil
Correct answer: Maximum dry density and optimum moisture content for compaction
The Proctor test identifies the optimum moisture content at which a soil achieves its maximum dry density when compacted, which is used to set compaction specifications.
Question 4: What is the optimal soil pH range for most cool-season turfgrasses used on sports fields?
- 4.5–5.5
- 6.0–7.0 (Correct answer)
- 7.5–8.5
- 8.0–9.0
Correct answer: 6.0–7.0
Cool-season grasses thrive at pH 6.0–7.0, the range at which macro and micronutrients are most available and soil microbial activity is optimized.
Question 5: Which amendment is most commonly added to heavy clay subsoils to improve drainage on sports fields?
- Peat moss
- Silt
- Coarse sand (Correct answer)
- Fine compost
Correct answer: Coarse sand
Coarse sand is added to clay soils to increase macropore space, which improves infiltration and drainage rates.
Question 6: What does Cation Exchange Capacity (CEC) indicate about a soil?
- The rate at which water drains through the profile
- The soil's ability to retain positively charged nutrient ions (Correct answer)
- The total carbon content of the soil
- The compressive strength of the soil under load
Correct answer: The soil's ability to retain positively charged nutrient ions
CEC measures the capacity of soil particles to hold and exchange cations such as calcium, magnesium, and potassium, which are essential plant nutrients.
Question 7: What is the primary purpose of a soil percolation test conducted during sports field site evaluation?
- To determine soil pH at various depths
- To measure the rate at which water moves through the soil profile (Correct answer)
- To assess surface compaction levels with a penetrometer
- To evaluate organic matter content using loss-on-ignition
Correct answer: To measure the rate at which water moves through the soil profile
A percolation test measures how quickly water infiltrates through the soil, which is critical data for designing adequate drainage systems.
CFB Soil Science & Amendments 1
What sand particle size range does the USGA recommend for sports field root zones?