Soils 205- General Soils

Quiz 1 Study questions

 

 

 

1.  What are the five main functions of soils in any ecosystem?

 

2.  In an ideal agricultural soil in good physical condition, approximately what proportion of the total volume is comprised of pores?

 

3.  How are the proportions of soil air and water related?

 

4.  How are primary and secondary minerals different?

 

5.  Explain the relationship between the following terms:

            a.  soil profile and pedon

            b.  horizon and profile

            c.  E and B horizons 

            d.  O and A horizons 

            e.  hue, value, and chroma

 

6.  Give the most complete horizon designation (master symbol and subordinate distinction, if appropriate) for each of the following.

a.  sandy horizon with little soil development _____

b.  horizon with segregated CaCO3______

c.  eluvial horizon______

d.  horizon with properties of E and B horizon superimposed upon one another_______

e.  B horizon with accumulation of layer silicate clays_______

           

7.  What are the main agents that determine soil color?

           

8.  What are gleyed colors and what type of environmental conditions do they reflect?

 

9.  What valuable information can be gathered by studying soil morphology or horizonation?

 

10.  What are the three soil separates and how are they defined?  What properties or behavior does each soil separate contribute to soil?

             

11.  What is the difference between the texture of a soil and its structure?

 

12.  Using a textural triangle, determine the textural class name for three soils with the following particle size distribution:

Soil

% sand

% silt

% clay

1

22

60

18

   2

38

17

45

3

59

13

28

 

13.  Which is more susceptible to modification by soil management: Soil texture or soil structure? 

 

14.  Describe 6 types of soil structural units or peds and tell where each is most likely to occur in the profile.

           

15.  What is the difference between particle density and bulk density of soils?

 

16.  What is the relationship between the compaction of a soil and its bulk density?

 

17.  If a soil has a bulk density of 1.4 Mg/m3 and a particle density of 2.6 Mg/m3, what portion of the soil volume is pores and what portion is solid particles?

 

18.  A cylindrical core sampler (10 cm high x 10 cm diameter) is used for bulk density determination.  The collected sample weighs 1420 g.  After oven drying it weighs 1300 g. (show your work, and include units).

 

a.  What is the bulk density of this soil? Db = oven dry weight/vol.

b.  What is the % pore space?

c.  What can you say about the quality of this soil for plant growth based on your   

                  calculations?

 

19.  Why are the relative amounts of macropores and micropores important to air and water movement in soils and how can these be influenced by soil management?

 

20.  What are the components of soil strength in cohesive and noncohesive soils?

           

21.  How do we measure soil strength in cohesive and noncohesive soils?

 

22.  What are “expansive soils” and why are they a problem?

 

23.  How does organic matter influence aggregation?

 

24.  What four guidelines for maintaining soil tilth.  Explain the reasoning behind each guideline.