ABSTRACT
Historically, soil and its fertility have been associated with providing enough food to support man’s survival on earth. After many millennia since the beginning of settled agriculture, that perception of the primary function of soils has shifted at least for a large swathe of the globe. Although hunger is still stalking many of the world’s poor (Borlaug, 2003), soil resources have taken on a broader dimension. With the world’s population currently at unprecedented levels, the major global concern of the 21st century are food security, soil degradation by land misuse and soil management, and anthropogenic increases in atmospheric greenhouse gases (Lal, 2001). As available land area per capita decreases, a major challenge to society is to sustainably use the world’s soil and water resources (Lal, 2000). The extent to which any ecosystem can withstand land-use pressure or its resilience or potential to recover from a degraded state is a function of the ecosystem in question, with semiarid and arid regions being particularly vulnerable (Stewart and Robinson, 1997). The extent to which any land can be sustainably farmed depends on soil quality from the physical, chemical and biological perspectives (Karlen et al., 2001).
