A soil 80 cm deep has a volume water content = 0.12. Find out the quantity of water that must be added to bring the volume water content to 0.30.

Correct option is C

Step-by-step explanation:
· Given:
· Initial volumetric water content, θv1=0.12\theta_{v1} = 0.12θv1​=0.12
· Final volumetric water content, θv2=0.30\theta_{v2} = 0.30θv2​=0.30
· Soil depth, D=80D = 80D=80 cm
· Increase in volumetric water content:
· Δθv=θv2−θv1=0.30−0.12=0.18\Delta \theta_v = \theta_{v2} - \theta_{v1} = 0.30 - 0.12 = 0.18Δθv​=θv2​−θv1​=0.30−0.12=0.18
· Quantity of water to be added (as water depth):
· Water depth=Δθv×D\text{Water depth} = \Delta \theta_v \times DWater depth=Δθv​×D
· =0.18×80=14.4= 0.18 \times 80 = 14.4=0.18×80=14.4 cm
· Interpretation:
· This means 14.4 cm of water (or 144 mm) must be added uniformly to the 80 cm soil profile.
Why other options are incorrect (brief):
· (a) 9.6 → Underestimates the required increase in water content.
· (b) 24.0 → Overestimates the water addition.
· (d) 18.4 → Does not match the calculated value from given data.
Key Points
· Volumetric water content change multiplied by soil depth gives water depth required.