Controls on Soil Processes

Why are soils so varied?

The presence of horizons in all reasonably mature soils is essentially driven by the same basic set of pedogenic processes.

There are a set of processes that are the same the world over. However, these processes operate at different rates and with different levels of importance under different environmental conditions or locations.

Natural pedogenesis can result in many different soil types and sub-types. Varied emphasis on different controls  etc. can therefore produce a different product.

The 5 main controls are:

• Parent Material

Composition of the regolith is dependent upon weathering processes and the nature of the soil's parent material. The way a rock weathers can also exert an influence over the particle size, properties of the resultant soil and effects its permeability.

• Organic Material

Difficult to isolate this effect as the type of fauna and flora that will develop in an area is strongly influenced by the soil type. E.g. the decay of different vegetation types produces humus that can be either mor (very…