Landscape Design Soil Science and Irrigation 2 — Questions and Answers
Question 1: What is 'soil compaction' and how does it affect landscape plants?
- Over-fertilization that burns plant roots
- Compression of soil particles that reduces pore space, limiting air, water, and root penetration (Correct answer)
- The hardening of soil surface due to sun exposure
- Excessive salt buildup in the root zone
Correct answer: Compression of soil particles that reduces pore space, limiting air, water, and root penetration
Soil compaction reduces the pore spaces between soil particles, limiting oxygen, water infiltration, and the ability of roots to penetrate and grow.
Question 2: An irrigation system's 'precipitation rate' refers to:
- The amount of rainfall a site receives annually
- The rate (inches per hour) at which a sprinkler system applies water (Correct answer)
- The frequency of irrigation cycles per week
- The water pressure at the main supply line
Correct answer: The rate (inches per hour) at which a sprinkler system applies water
Precipitation rate is the amount of water applied by an irrigation system per unit time (inches per hour), which must be matched to soil infiltration rate to prevent runoff.
Question 3: What does 'ET' (evapotranspiration) represent in irrigation scheduling?
- Emergency treatment for overwatered plants
- The combined water loss from soil evaporation and plant transpiration (Correct answer)
- The efficiency rating of a sprinkler head
- The electrical conductivity of irrigation water
Correct answer: The combined water loss from soil evaporation and plant transpiration
Evapotranspiration (ET) represents the total water lost from the landscape through soil evaporation and plant transpiration, used to calculate replacement irrigation needs.
Question 4: Which soil amendment is commonly used to improve drainage in heavy clay soils?
- Peat moss
- Compost
- Coarse sand or perlite (Correct answer)
- Lime
Correct answer: Coarse sand or perlite
Coarse sand or perlite added to clay soil increases pore space and improves drainage by breaking up the dense clay particle structure.
Question 5: What is a 'rain sensor' or rain shutoff device in a landscape irrigation system?
- A meter that tracks total annual rainfall
- A device that automatically suspends irrigation when sufficient rainfall occurs (Correct answer)
- A sensor that activates irrigation when rain is forecast
- A controller that adjusts water pressure based on weather
Correct answer: A device that automatically suspends irrigation when sufficient rainfall occurs
A rain sensor automatically shuts off the irrigation system when it detects a set amount of rainfall, preventing overwatering and wasting water after natural precipitation.
Question 6: What is 'backflow prevention' in a landscape irrigation system?
- A valve that prevents water from flowing backward from the irrigation system into the potable water supply (Correct answer)
- A system that recycles runoff water back into the irrigation tank
- A pressure regulator that prevents pipe bursting
- A filter that prevents debris from entering sprinkler heads
Correct answer: A valve that prevents water from flowing backward from the irrigation system into the potable water supply
Backflow prevention devices stop contaminated irrigation water from flowing backward into the drinking water supply, required by most US plumbing codes.
Landscape Design Soil Science and Irrigation 2
What is 'soil compaction' and how does it affect landscape plants?