Answer to Question 1
Forest soils (temperate-zone forests) have thin A horizons, thick O horizons, abundant clay in the B horizon. Rainforest soils (tropical forests) are dominated by intense chemical weathering and so the soils are infertile due to the destruction of nutrients. Accumulations of aluminum hydroxides (bauxite) and iron rich soils (iron ore) are important economically. Grasslands soils (drier than forests) are dominated by thick A horizons which are not readily leached. Desert soils (dry, little vegetation) do not have much organic material in the A horizon, but retain nutrients due to the low rainfall. They have a poorly developed B horizon that often contains calcite. Wetland soils contain only O and A horizons because the soils are so saturated that no waters can reach downward to create the B horizon. The organics are so abundant that available oxygen is low, and so they can't readily dissolve. This leads to very organic-rich sediments, which when compacted, are mined as peat.
Answer to Question 2
There is no farming in the steep ravines, where disturbance of the soil for planting would enhance erosion. Some of the planting has been done along the contours of the landscape, which slows down potentially erosive water runoff along the surface. Land planted in wheat alternates with strips of land that remain covered in native grasses; this means that there is always some plant cover present year-round to slow down erosion by water and wind.
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William Kentridge, History of the Main Complaint.
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