IA Irrigation Scheduling & Evapotranspiration 1 — Questions and Answers
Question 1: Which term describes the combined process of water evaporation from soil and transpiration from plants?
- Precipitation
- Evapotranspiration (Correct answer)
- Infiltration
- Percolation
Correct answer: Evapotranspiration
Evapotranspiration (ET) is the combined water loss through evaporation from soil surfaces and transpiration from plant leaves.
Question 2: Reference evapotranspiration (ETo) is most commonly calculated using which method recognized by the FAO?
- Blaney-Criddle method
- Hargreaves method
- Penman-Monteith method (Correct answer)
- Thornthwaite method
Correct answer: Penman-Monteith method
The FAO-56 Penman-Monteith equation is the globally recognized standard for calculating reference evapotranspiration.
Question 3: A crop coefficient (Kc) is used to adjust ETo for a specific crop. What does a Kc value of 1.2 indicate?
- The crop uses 20% less water than the reference crop
- The crop uses 20% more water than the reference crop (Correct answer)
- The crop uses the same amount as reference
- The soil is 20% saturated
Correct answer: The crop uses 20% more water than the reference crop
A Kc of 1.2 means the actual crop evapotranspiration (ETc) is 20% greater than the reference ETo.
Question 4: Which irrigation scheduling method uses soil moisture sensors to determine when to irrigate?
- Calendar-based scheduling
- Checkbook method
- Soil water depletion method (Correct answer)
- Evaporation pan method
Correct answer: Soil water depletion method
The soil water depletion method uses sensors such as tensiometers or capacitance probes to monitor soil moisture and trigger irrigation at a set threshold.
Question 5: What is the Management Allowable Depletion (MAD) typically set at for most turf and landscape irrigation?
- 10–20%
- 25–40% (Correct answer)
- 50–60%
- 70–80%
Correct answer: 25–40%
MAD for turf and landscape is typically set between 25–40% of plant available water to avoid plant stress.
Question 6: An irrigation controller that automatically adjusts run times based on local ET data is called a:
- Time-based controller
- Smart or ET-based controller (Correct answer)
- Interval timer
- Hydraulic controller
Correct answer: Smart or ET-based controller
Smart or ET-based controllers use weather data or on-site sensors to continuously adjust irrigation schedules to match actual plant water needs.
IA Irrigation Scheduling & Evapotranspiration 1
Which term describes the combined process of water evaporation from soil and transpiration from plants?