1. How does the structure of a water molecule influence its properties and behavior in soil?

2. A moist soil sample is collected in the field. The weight of the sample is 850 g and it has a volume of 485 cm3. After oven-drying, the sample weighs 620 g. What is the water content by weight? What is the water content by volume? What would be the volume water content of this soil at saturation?

3. What is the advantage of using soil water energy to describe the water status of a soil?

4. Which contains more water available to plants - a sandy loam at wilting point or a clay loam at wilting point? Why?

5. Draw a graph showing the relationship between soil water potential and soil water content for a loamy sand and a clay.

6. Consider the following statement - water always moves downward in a soil. Do you agree or disagree with this statement? Why or why not?

7. Consider a soil profile in which a loamy sand E horizon overlies sandy clay Bt horizon. If the soil is allowed to wet up as irrigation water is continually added to the surface, what will happen when the wetting front reaches the contact between these 2 horizons? Why?

8. Consider a soil profile in which a sandy clay Bt horizon overlies a loamy sand C horizon. If the soil is allowed to wet up as irrigation water is continually added to the surface, what will happen when the wetting front reaches the contact between these 2 horizons? Why?

9. Draw a graph that shows the relationship between hydraulic conductivity and soil water potential for a loamy sand and a clay.

10. Why would moderately coarse texture generally be preferred over fine textures for irrigation?

11. Andisols are the most productive forest soils of northern Idaho. A typical volcanic ash mantle has thickness of 50 cm and a texture of silt loam and overlies gravelly and sandy horizons. How much plant available water does this mantle impart to the soil? How is this mantle linked to the productivity of northern Idaho forests?

12. Describe how water potential changes as it goes from a soil into a plant root, from a root up into plant leaves, and finally back into the atmosphere.

13. The general wate balance equation for soils is given as:

Precipitation = Evapotranspiration +Soil Storage + Surplus

Explain each of these components and describe the most important factors that determine each. For example, what factors determine evapotranspiration?

14. What are some of the environmental processes associated with surplus water?

15. Describe how some of the components of the water balance equation can be altered through management.

16. What are some of the benefits of irrigation? What are some negative aspects of irrigation?

17. What is the purpose of installing tile drains in wet soils?

18. How is poor aeration related to the percentage of water-filled pores?

19. Draw a graph showing the relationship between soil water content and soil Eh status.

20. What 3 criteria are used to define wetlands?

21. What are some of the ecological functions of wetlands?