CPESC Vegetative Stabilization 3 — Questions and Answers
Question 1: What term describes the percentage of viable seeds in a seed lot, used to calculate the actual seeding rate needed to achieve a target plant population?
- Germination percentage
- Pure live seed (PLS) (Correct answer)
- Bulk weight
- Seed vigor index
Correct answer: Pure live seed (PLS)
Pure live seed (PLS) = (germination % × purity %) / 100, and is used to standardize seeding rates across seed lots of varying quality.
Question 2: Sodding is preferred over seeding for erosion control in which specific situation?
- Large areas with minimal slope
- Areas requiring immediate stabilization where seeding establishment time is unavailable (Correct answer)
- Sites with highly acidic soils
- Areas where permanent vegetation is not required
Correct answer: Areas requiring immediate stabilization where seeding establishment time is unavailable
Sod provides immediate ground cover and erosion protection the day it is installed, making it ideal for sites where delays in establishing vegetation are unacceptable.
Question 3: Which factor most limits the establishment of vegetation on mine spoil or highly acidic industrial fill material?
- Excessive soil moisture
- Extremely low pH and presence of phytotoxic heavy metals (Correct answer)
- High organic matter content
- Overly coarse soil texture
Correct answer: Extremely low pH and presence of phytotoxic heavy metals
Mine spoils often have pH values below 3.5 and contain heavy metals like aluminum and manganese at concentrations toxic to most plants, requiring extensive amendment.
Question 4: What is the recommended minimum fertilizer application rate for nitrogen (N) when establishing permanent vegetation on nutrient-poor disturbed soils, absent a soil test?
- 10 lbs N/acre
- 20-40 lbs N/acre
- 60-80 lbs N/acre (Correct answer)
- 100-120 lbs N/acre
Correct answer: 60-80 lbs N/acre
A standard starter fertilizer application of 60-80 lbs N/acre is typically recommended for disturbed soils when soil test data is unavailable.
Question 5: Which native grass species is most commonly specified for erosion control seedings in the tallgrass prairie region of the central United States?
- Tall fescue (Festuca arundinacea)
- Big bluestem (Andropogon gerardii) (Correct answer)
- Bermudagrass (Cynodon dactylon)
- Annual ryegrass (Lolium multiflorum)
Correct answer: Big bluestem (Andropogon gerardii)
Big bluestem is the dominant native warm-season grass of the tallgrass prairie and is widely specified for native revegetation projects in the central US.
Question 6: When installing sod on a slope steeper than 2:1, which additional practice is required to prevent sod from slipping before it roots?
- Applying additional fertilizer
- Staking or stapling individual sod pieces to the slope (Correct answer)
- Irrigating heavily immediately after installation
- Placing sod in a staggered brick-like pattern only
Correct answer: Staking or stapling individual sod pieces to the slope
On slopes steeper than 2:1, sod must be anchored with stakes or staples driven through each piece to prevent downslope displacement before roots establish.
Question 7: A hydraulic seeding contractor is applying a wood fiber mulch at 2,000 lbs/acre with seed and fertilizer. What is the primary function of the wood fiber in this mixture?
- Providing plant nutrients
- Creating a moisture-retaining matrix that protects seed from desiccation and erosion (Correct answer)
- Suppressing weed germination
- Increasing soil pH
Correct answer: Creating a moisture-retaining matrix that protects seed from desiccation and erosion
Wood fiber mulch in hydroseeding creates a protective matrix over the seeded area that retains soil moisture, moderates soil temperature, and reduces raindrop impact.
CPESC Vegetative Stabilization 3
What term describes the percentage of viable seeds in a seed lot, used to calculate the actual seeding rate needed to achieve a target plant population?