ABSTRACT
Soils not only respond to environmental conditions, but can also influence these conditions and therefore play an important role in the operation of environmental systems. These systems can be divided into four main types-the hydrosphere, atmosphere, geosphere and biosphere (section 1.1). Although these environmental components are in many ways interrelated, this chapter aims to examine the role of soil in each system separately in order to provide a clearer understanding of the processes involved. We will start by examining the hydrosphere because soil moisture is one of the main keys to soil-environmental influences, and many of the aspects relating to the hydrosphere are therefore relevant to those of the other systems. Having first introduced some basic concepts, various components of the hydrological cycle will then be considered. Closely related to the hydrosphere is the atmosphere, with soils exerting an important influence on climate at or near the ground surface, and this is considered next. The geosphere is then examined with respect to the role of soil in geomorphic processes and landform development. Finally, we consider the biosphere, in which soils are an important factor in controlling the habitation and distribution of biota. This chapter will concentrate predominantly on natural environmental conditions; the important human aspect of soil-environmental relationships will be discussed separately in the following two chapters.
