ABSTRACT
Soil is a product of the interaction of climate with bedrock; the properties of the soil produced are determined by ancillary factors such as the position of the site on the landscape and the vegetation present. All this, in combination in various proportions, in¦uence the kind of biota that dwells on or in the soil, which also contribute to the soil’s development. The intensity of each of these factors and their interactions
3.1 Introduction ....................................................................................................29 3.2 Global Distribution of Soils ............................................................................ 32
3.2.1 Al…sols ................................................................................................ 32 3.2.2 Andisols .............................................................................................. 32 3.2.3 Aridisols.............................................................................................. 32 3.2.4 Entisols ............................................................................................... 37 3.2.5 Gelisols ............................................................................................... 37 3.2.6 Histosols ............................................................................................. 37 3.2.7 Inceptisols ........................................................................................... 37 3.2.8 Mollisols ............................................................................................. 43 3.2.9 Oxisols ................................................................................................ 43 3.2.10 Spodosols ............................................................................................ 43 3.2.11 Ultisols ................................................................................................ 43 3.2.12 Vertisols .............................................................................................. 47
3.3 Historical Trends ............................................................................................ 47 3.4 Current Issues ................................................................................................. 49
3.4.1 Opportunities ...................................................................................... 49 3.4.2 Challenges........................................................................................... 49
3.5 Future Perspectives .........................................................................................50 3.6 Conclusions ..................................................................................................... 51 References ................................................................................................................ 51
determine the nature of the product. Many of the factors are rhythmic with intensities varying with time. The changes may be diurnal and/or seasonal and knowing the climatic endowments of the area may be predictable. The human factor in the development of the soil is intriguing and has been the subject of innumerable studies. Most such studies describe the dramatic or obvious changes or changes that are measurable with available devices. However, land use also induces changes that are generally imperceptible. This includes such features as thickness of surface organic rich horizons. Changes in intensity and direction of processes are seldom evaluated unless they result in recognizable features. Soil management requires fertilization and in some instances copious amounts of fertilizers are added to the soil. This alters the microenvironment of the topsoil having consequences on the biota and processes that operate in the soil. This aspect of soil development has not received the study it deserves; most such studies focus on the fate of the organisms or the response of the soil to management and less on the microenvironmental changes within the soil. In the absence of a better understanding of the changes, soil management will remain ad hoc and contribute less to the sustainability of the system.
