Irrigation - Engineering

Q1:

The field capacity of a soil is 25%, its permanent wilting point is 15% and specific dry unity weight is 1.5. If the depth of root zone of a crop, is 80 cm, the storage capacity of the soil, is

A 8 cm

B 10 cm

C 12 cm

D 14 cm

E 16 cm

ANS:C - 12 cm

For formula is
(Yd/Yw)*d*(field capacity-permanent welting point);
Given data:
Yd=1.5,
Yw=1,
Depth zone=80 cm,
Field capacity = 25% = 25/100 = 0.25,
Permanent wilting point = 15% = 15/100 = 0.15,
So, (1.5/1)*80*(0.25-0.15) = 12 cm,
The Correct answer is 12 cm.