Lab: Quality of Soils
The purpose of this lab is to compare the porosity and permeability of different soil samples and to use this
information to predict the ability of soils to support crops.
Permeability = the velocity that water travels through soils
Porosity = the space between soil particles
pH = the negative log of the concentration of hydrogen ions
PROCEDURE:
DATA:
See the instruction sheet
Attach your chart of data and drawings to the back of this paper.
SUMMARY QUESTIONS:
1. How does humus get added to soils? What is the value of humus? How do you recognize a soil that contains
high levels of humus?
2. Why does the A horizon in Ramona contain very little humus?
3. How does porosity affect the frequency of irrigation?
4. Some soils have good porosity but poor permeability. Which kinds of crops would do best in soil
of this type?
5. After a rainstorm Cindy’s driveway seems to dry out very quickly. The driveway will be muddy for only one or
two days. Predict the porosity and permeability of the soil in Cindy’s driveway.
6. After the same rainstorm, Levi may see shallow pools of water on his ranch that can last for as long as four
weeks. These are called vernal pools and will support their own ecosystem. Predict the porosity and permeability
of the soil on Levi’s ranch.
7. There used to be a huge vernal pool on the property beneath Stater Brothers grocery store. Before the store
could be built, the EPA dictated that the vernal pool had to be relocated elsewhere. Describe one ecological
problem and one economic problem with this EPA directive.
8. What is quicksand? How do you get out of it?
9. The instructions on the label said “Plant this orange tree in soil with rapid permeability.” What does that mean?
What will happen to the roots of this tree if the permeability is slow?
10. Soils form more rapidly on the Big Island in Hawaii than they do in Anchorage, Alaska or in Reno, Nevada.
Explain.
11. Ashes from eucalyptus and oak tend to be alkaline. The soils in Western USA also tend to be alkaline, so in
Ramona it isn’t a good idea to dump ashes from the fireplace or wood-burning stove around your landscape
plants. However, in Eastern USA it is okay to dump ashes around landscape plants. Explain.
12. List three mechanical (or physical) forces that weather the rocks on Mt Woodson.
13. List three chemical forces that weather the rocks on Mt. Woodson.
14. List three functions of soil.