The GATE Grind

GATE 2020 CE (CE1) – Question 25

Irrigation · Irrigation systems and methods, crop water requirements · 1 mark · Multiple choice

For one month an agricultural field has pan evaporation 100 mm, effective rainfall 20 mm after runoff/deep-percolation losses, crop coefficient 0.4 and irrigation efficiency 0.5. Find irrigation water depth to apply (mm).

  1. 0
  2. 20
  3. 40
  4. 80

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Show answer and explanation

Correct answer: (C) 40

Explanation

Crop demand is $0.4(100)=40$ mm. Effective rainfall leaves $40-20=20$ mm net irrigation. Gross depth is $20/0.5=40$ mm. **C**.