AZ L-91 Irrigation Systems Contractor Exam
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
Question 1
What is the primary purpose of an irrigation system?
a) To increase soil compaction
b) To provide water to plants in a controlled and efficient manner
c) To eliminate the need for soil preparation
d) To prevent all water from entering the soil
Correct Answer: b) To provide water to plants in a controlled and
efficient manner
Rationale: An irrigation system delivers water to landscaped areas or
agricultural crops according to their water requirements. Properly
designed systems distribute water uniformly, maintain healthy plant
,growth, and minimize water waste caused by runoff, evaporation, or
excessive application.
Question 2
Which factor is most important when determining the irrigation water
requirements of a landscape?
a) The color of the irrigation pipes
b) The number of valves installed
c) Plant type, climate, soil conditions, and evapotranspiration
d) The brand of irrigation controller
Correct Answer: c) Plant type, climate, soil conditions, and
evapotranspiration
Rationale: Irrigation requirements depend on the amount of water
plants lose through evapotranspiration, along with local weather, plant
species, rooting depth, and soil characteristics. These factors determine
how frequently and how much water should be applied.
Question 3
What does evapotranspiration (ET) represent?
a) Water lost through evaporation from soil and plant surfaces and
transpiration from plants
,b) Water absorbed exclusively by plant roots
c) Water discharged from an irrigation pump
d) Water stored permanently below the root zone
Correct Answer: a) Water lost through evaporation from soil and plant
surfaces and transpiration from plants
Rationale: Evapotranspiration combines evaporation from soil and
other wet surfaces with transpiration through plant leaves. ET is
commonly used to estimate landscape water demand and establish
irrigation schedules.
Question 4
Which irrigation method generally delivers water directly to the root
zone at relatively low flow rates?
a) Flood irrigation
b) Overhead spray irrigation
c) High-pressure misting
d) Drip irrigation
Correct Answer: d) Drip irrigation
Rationale: Drip irrigation applies water through emitters positioned
near plants. This method can reduce evaporation and runoff by
, delivering water close to the root zone, provided the system is properly
designed, filtered, maintained, and operated.
Question 5
What is the main purpose of a backflow prevention device in an
irrigation system?
a) To increase the operating pressure of sprinkler heads
b) To prevent contaminated irrigation water from flowing back into the
potable water supply
c) To regulate the irrigation controller's electrical current
d) To remove all sediment from irrigation water
Correct Answer: b) To prevent contaminated irrigation water from
flowing back into the potable water supply
Rationale: Backflow prevention protects potable water supplies from
contamination caused by backpressure or backsiphonage. The required
device depends on the water system, potential hazards, local plumbing
codes, and the irrigation installation.
Question 6
Which condition can cause backsiphonage in an irrigation system?
a) A sprinkler head operating below its rated flow
Questions and Correct Answers (Verified
Answers) Plus Rationale 2027 Q&A|
Instant Download Pdf
Question 1
What is the primary purpose of an irrigation system?
a) To increase soil compaction
b) To provide water to plants in a controlled and efficient manner
c) To eliminate the need for soil preparation
d) To prevent all water from entering the soil
Correct Answer: b) To provide water to plants in a controlled and
efficient manner
Rationale: An irrigation system delivers water to landscaped areas or
agricultural crops according to their water requirements. Properly
designed systems distribute water uniformly, maintain healthy plant
,growth, and minimize water waste caused by runoff, evaporation, or
excessive application.
Question 2
Which factor is most important when determining the irrigation water
requirements of a landscape?
a) The color of the irrigation pipes
b) The number of valves installed
c) Plant type, climate, soil conditions, and evapotranspiration
d) The brand of irrigation controller
Correct Answer: c) Plant type, climate, soil conditions, and
evapotranspiration
Rationale: Irrigation requirements depend on the amount of water
plants lose through evapotranspiration, along with local weather, plant
species, rooting depth, and soil characteristics. These factors determine
how frequently and how much water should be applied.
Question 3
What does evapotranspiration (ET) represent?
a) Water lost through evaporation from soil and plant surfaces and
transpiration from plants
,b) Water absorbed exclusively by plant roots
c) Water discharged from an irrigation pump
d) Water stored permanently below the root zone
Correct Answer: a) Water lost through evaporation from soil and plant
surfaces and transpiration from plants
Rationale: Evapotranspiration combines evaporation from soil and
other wet surfaces with transpiration through plant leaves. ET is
commonly used to estimate landscape water demand and establish
irrigation schedules.
Question 4
Which irrigation method generally delivers water directly to the root
zone at relatively low flow rates?
a) Flood irrigation
b) Overhead spray irrigation
c) High-pressure misting
d) Drip irrigation
Correct Answer: d) Drip irrigation
Rationale: Drip irrigation applies water through emitters positioned
near plants. This method can reduce evaporation and runoff by
, delivering water close to the root zone, provided the system is properly
designed, filtered, maintained, and operated.
Question 5
What is the main purpose of a backflow prevention device in an
irrigation system?
a) To increase the operating pressure of sprinkler heads
b) To prevent contaminated irrigation water from flowing back into the
potable water supply
c) To regulate the irrigation controller's electrical current
d) To remove all sediment from irrigation water
Correct Answer: b) To prevent contaminated irrigation water from
flowing back into the potable water supply
Rationale: Backflow prevention protects potable water supplies from
contamination caused by backpressure or backsiphonage. The required
device depends on the water system, potential hazards, local plumbing
codes, and the irrigation installation.
Question 6
Which condition can cause backsiphonage in an irrigation system?
a) A sprinkler head operating below its rated flow
