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Irrigation Scheduling & Evapotranspiration Flashcards

6 cards from real IA practice questions. Tap to flip, then mark Knew It or Still Learning — missed cards come back until you master them.

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  1. Which weather variable has the greatest influence on reference evapotranspiration (ETo) in humid climates?

    Answer: Net radiation

    Net radiation is typically the dominant driver of ETo in humid climates where vapor pressure deficit is lower.

  2. The 'checkbook method' of irrigation scheduling tracks what two primary inputs?

    Answer: Rainfall and ET

    The checkbook method balances rainfall and ET as deposits and withdrawals to maintain soil moisture within an acceptable range.

  3. What does the term 'irrigation interval' refer to?

    Answer: The number of days between irrigation events

    Irrigation interval is the number of days between scheduled watering events, determined by depletion rate and MAD.

  4. If daily ETo is 0.25 inches and the crop coefficient is 0.8, what is the daily crop water use (ETc)?

    Answer: 0.20 inches

    ETc = ETo × Kc = 0.25 × 0.8 = 0.20 inches per day.

  5. Which instrument is used to directly measure reference evapotranspiration in the field?

    Answer: Lysimeter

    A lysimeter is a precision device that measures actual water use by plants by weighing or monitoring drainage from an isolated soil-plant system.

  6. Which factor does NOT directly influence evapotranspiration rates?

    Answer: Soil pH

    Soil pH affects nutrient availability and plant health but is not a direct meteorological driver of evapotranspiration.

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  1. irrigation.org — Exam format, time limit, eligibility, test delivery, passing score, registration deadline, retake policy, exam information · verified Oct 2026