42.8. Moisture Movement in Unsaturated Soil

Try these first

1. 1.

   What does unsaturated soil mean?

   Hint

   Think about what it means for soil to be partially filled.

2. 2.

   What is Darcy's Law used to describe?

   Hint

   It relates to how fluids move in soils.

3. 3.

   What equation represents Darcy's Law for unsaturated flow?

   • q = K * (dh/dz)
   • q = -K(θ) * (dh/dz)
   • q = K + (dh/dz)

   Hint

   Look for the negative sign involved in the formula.

4. 4.

   True or False: Hydraulic conductivity increases in compacted soils.

   • True
   • False

   Hint

   Consider how compaction affects water flow.

5. 5.

   Calculate the flux of water in a sandy soil with a hydraulic conductivity of 10 cm/hr and a matric potential gradient of 0.5. Use Darcy's Law.

   Hint

   Remember to multiply the hydraulic conductivity by the gradient.

6. 6.

   If a compacted clay soil has a hydraulic conductivity of 1 cm/hr, how does this affect irrigation scheduling compared to a loamy soil with 5 cm/hr?

   Hint

   Think about how the differences in hydraulic conductivity will influence water availability for crops.