CH Irrigation and Water Management 1 — Questions and Answers
Question 1: Which irrigation system delivers water directly to the root zone with the greatest water-use efficiency?
- Overhead sprinkler
- Drip/micro-irrigation (Correct answer)
- Flood irrigation
- Sprinkler oscillation system
Correct answer: Drip/micro-irrigation
Drip irrigation applies water slowly at or below the soil surface directly to the root zone, minimizing evaporation and runoff compared to overhead methods.
Question 2: Evapotranspiration (ET) represents the combined water loss from:
- Rainfall and irrigation
- Soil evaporation and plant transpiration (Correct answer)
- Deep percolation and runoff
- Root uptake and guttation
Correct answer: Soil evaporation and plant transpiration
ET combines evaporation from soil surfaces and transpiration from plant leaves, and is used to calculate irrigation replacement needs.
Question 3: A distribution uniformity (DU) test for a sprinkler system measures:
- Soil moisture at various depths
- How evenly water is applied across the irrigated area (Correct answer)
- Water pressure at each head
- Flow rate from each emitter
Correct answer: How evenly water is applied across the irrigated area
DU compares catch-can volumes across the irrigated zone to determine how uniformly water is distributed; low DU indicates dry spots requiring over-irrigation elsewhere.
Question 4: Which condition is an early visible sign of plant water stress (drought stress)?
- Leaf curl or wilting in the morning (Correct answer)
- Leaf yellowing starting from the base
- Purple stem coloration
- Sudden drop of fruit
Correct answer: Leaf curl or wilting in the morning
Temporary wilting or leaf rolling/curling during morning hours (before midday heat) indicates significant water deficit and is an early stress indicator in many species.
Question 5: Irrigation scheduling based on soil moisture sensors is preferred over calendar-based scheduling because it:
- Is always less expensive to install
- Applies water only when plants actually need it, reducing overwatering (Correct answer)
- Works without any maintenance
- Eliminates the need for a controller
Correct answer: Applies water only when plants actually need it, reducing overwatering
Soil moisture sensors measure actual water content in the root zone, allowing irrigation to trigger only when plants need water rather than on a fixed schedule regardless of conditions.
Question 6: Backflow prevention devices on irrigation systems are required in the US primarily to:
- Increase water pressure
- Prevent contaminated irrigation water from entering the potable water supply (Correct answer)
- Filter sediment from emitters
- Reduce water hammer in pipes
Correct answer: Prevent contaminated irrigation water from entering the potable water supply
Backflow preventers protect public drinking water supplies from being contaminated by chemicals, fertilizers, or pathogens that may enter the irrigation system.
CH Irrigation and Water Management 1
Which irrigation system delivers water directly to the root zone with the greatest water-use efficiency?