1. Scott Werts Winthrop University

2. Design of Activity  Activity designed as a homework assignment  Work assigned after lecture material and reading on cation exchange processes in soils.  Students are not to work in groups, and each is responsible for choosing their own locations to investigate  Students in this course already have a background in using the NRCS Online Soil Survey

3. Assignment Basics  Students are to compare the cation exchange capacity of a particular set of soils with the aspects of that soil that influence the CEC. (pH, organic material and clay)  Students may chose any location they wish Most chose their address or an address of their relatives.

4. Assignment Basics  Students look at this data at two separate depths Each set of data is taken from 0-10 cm and 10-20 cm. This gives the students an idea of variation within the area laterally with different soil types and vertically within the same soil type.

5. Familiarity with the Online Soil Survey  Online Soil Survey Online Soil Survey  A clearing house of very basic data regarding soils.

7. Assessment  Students are to turn in: The map of the Area of Interest they created (AOI) A Table displaying ○ Soil types ○ CEC ○ Percent Clay ○ Percent Carbon ○ pH Explanation of trends….

8. Assessment  Trends What should be: ○ As CEC goes up pH goes down Organic Content goes up Clay goes up Sometimes there is variation ○ pH will go down as organic content goes up, for example

9. Variation from the norm:  Have the students assess the magnitude of the differences. For example – a 10% increase in organic matter may be a stronger driver for an increase in CEC than a 0.2 drop in pH.

10. Variation from the norm:  Not fool-proof At least once, there was a trend even I, the professor, could not explain. Reinforce that the soil survey isn’t perfect and should represent a generalized trend I had the student write what should influence the CEC and state that the data bucked the traditional trend we discussed in class

14. Questions? Happy students!