Question Bank • QB_IDE_EXP_008 NAT • 2 Marks

Section 5: Irrigation and Drainage Engineering

Soil-Water-Plant Relationship

Subtopic: Measurement of infiltration, soil moisture and irrigation water infiltration

Question Statement:

A soil core of diameter $5.0\text{ cm}$ and length $10.0\text{ cm}$ had a moist weight of $340\text{ g}$. After oven-drying at $105^\circ\text{C}$ for 24 hours, the dry weight was $295\text{ g}$. The dry bulk density of the soil in $\text{g/cm}^3$ is ________ (round off to 2 decimal places).

Answer Key:

1.5

Step-by-Step Solution & Explanation

1. Volume of the cylindrical soil core $V$: $V = \frac{\pi}{4} D^2 L = \frac{\pi}{4} (5.0)^2 \times 10.0 = \frac{\pi}{4} \times 25 \times 10 = 196.35\text{ cm}^3$ 2. Dry bulk density $\rho_b = \frac{M_s}{V}$: $\rho_b = \frac{295\text{ g}}{196.35\text{ cm}^3} \approx 1.5024\text{ g/cm}^3 \approx 1.50\text{ g/cm}^3$
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