Productive soils and clean water are essential elements for economic and social prosperity and environmental sustainability. Throughout history, civilizations have thrived or collapsed based on the availability of these vital resources. The lack of arable land and evidence of soil degradation have been identified as causes for the fall of many ancient civilizations, such as those in Mesopotamia, the Anasazi in the western United States, and the Mayans of Central America.

The rise and fall of these civilizations is often attributed to accelerated erosion and degradation caused by improper land management or scarce resources. We must understand and remember the lessons of the past, for those who do not heed these lessons are most likely to repeat them. Materials for the two volumes of "Soil and water conservation"were presented at the 8th International Soil Conservation Organization (ISCO)Conference, New Delhi , December 4-8,1994