Qs about old exams

3. Ahb horizon. 1st give definitions for h and b (and consider the processes their associated processes). 2nd think about the environmental conditions which may commonly lead to the formation of an Ahb horizon. Note that erosion implies the removal of soil (not deposition) but you are on the right track.

4. Sources of P and S. Review the P and S cycles AND slide 16 of lecture 25 (soil as a source of plant nutrients). Sulfide minerals, phosphate minerals and SOM are important sources.