SOIL SCIENCE MINIMUM COMPETENCIES AND PERFORMANCE OBJECTIVES

The following is a list of minimum competencies in soil chemistry and mineralogy that are needed by all
professional soil scientists. The list is something you might want to keep in mind as you go through the course.  I 
will not necessarily ask any specific questions relating to these (but, then again, I may!), but you will see them on 
the National Soil Science exam required if/when you apply for certification.

A. Basic concepts of soil chemistry.
        1. Define cation exchange capacity.
        2. Calculate approximate pH when given hydrogen ion activity, and vice versa.
        3. Describe field and laboratory methods for measuring soil pH.
        4. Describe how test method influences interpretation of pH.
        5. Describe how soil salts influence the interpretation of soil pH. 
        6. Describe the effect of buffering on acid-base reactions.
        7. Convert meq per 100 g and centimoles of charge per kilogram (cmolckg-1) to pounds per acre or              
           kilograms per ha (parts per 2 million) when given a depth and a bulk density specification.        

B. Mineral weathering.
        8. List the chemical and physical processes that contribute to mineral weathering.
        9. Identify the structures of the following clay minerals:
                a. kaolinite
                b. mica (illite)
                c. smectite (montmorillonite)
        10. Describe the major chemical and physical properties of the following clay minerals:
                a. kaolinite
                b. mica (illite)
                c. smectite (montmorillonite)

C. The nature of the soil solution. 
        11. Describe the difference in magnitude between cation concentration in soil solution and concentration    
            on the soil exchange sites.  
        12. Describe why CO2 has an acidifying effect on the soil solution.
        13. Define mass flow and diffusion, and list the major soil chemical and physical properties affection mass 
            flow and diffusion. 

D. Solid phase chemistry.
        14. List the approximate cation exchange capacity for humus, smectite, mica, and kaolinite.  
        15. Estimate cation exchange capacity when given soil organic matter content, clay content, and types of    
            clay.  
        16. Calculate cation exchange capacity, percent base saturation, and percent saturation with a given cation  
            of a soil when given the quantities of cations distributed on the exchange sites. 
        17. Define anion exchange capacity.
        18. Explain how change in soil pH influences the cation and anion exchange capacities of soils.  
        19. Differentiate between reserve and active acidity in a soil.  
        20. Explain how soil colloids buffer soil pH changes caused, for example, by acid rain, liming, and                   nitrogen fertilizers. 

E. Sorption and precipitation reactions.  
        21. Describe the relationship between soil pH and the chemical solubilities of these ions:
                a. aluminum, iron, copper, zinc, and manganese.
                b. calcium and magnesium.
                c. phosphate and molybdate. 
        22. Recognize the relative bonding strength of aluminum, calcium, magnesium, potassium, and sodium to  
            colloids with cation exchange capacity. 
        23. List factors affecting phosphate and nitrate mobility in soil.

F. Oxidation-reduction reactions.
        24. List conditions which lead to a soil becoming reduced.
        25. Identify soil ions most likely to be part of redox reactions.
        26. Describe how the redox state of the soil influences ion solubilities. 

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