3.4: Problem set

1. A cylindrical soil sample of 3.85 cm diameter and 10.00 cm height weights 201.13 g. The sample is then oven dried at 105°C for 48 hours, reaching a final weight of 177.75 g. Assume a particle density of 2.65 g cm^-3 and density of water 1.00 g cm^-3. Calculate the sample’s:

a. bulk density

b. porosity

c. gravimetric and volumetric water contents

d. soil water storage in mm

This video demonstrates the calculations step-by-step [websites]

2. Calculate the soil water storage in mm for a 60 cm deep soil profile in which the A horizon is 25 cm thick and has a volumetric water content of 0.25 cm³ cm^-3 and the B horizon is 35 cm thick and has a volumetric water content of 0.35 cm³ cm^-3.
3. Determine the correct value for x in the simplified capillary rise equation below using Equation 3-2 and assuming a contact angle of 20°. For water, assume a surface tension of 7.3 x 10^-2 N m^-1 (1 N m^-1 = 1 kg s^-2) and density of 998 kg m^-

4. Use the result from the prior question to calculate the height of capillary rise in a 0.010 mm diameter capillary tube.
5. Use the Campbell water retention function and data from Table 3-2 to find the volumetric water content of a sand and a clay loam at -10. kPa and -1500. kPa.

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