6.1 - Introduction

Goals: To introduce students to the basic functions of soil, and to evaluate regional differences in soil resources at the global scale.


  1. Identify and describe the roles of soil in the global ecosystem.
  2. Consider the impact of physical, chemical, and biological factors on soil functions.
  3. Identify cultural and environmental factors which affect the ability of soil to function.
  4. Evaluate the nature and extent of the global soil resource.

Figure 1.  Though it is commonly taken for granted, soil is an indispensable component in the cycles of life on Earth. Image courtesy of Tim Kettler.

Consider a handful of soil (Figure 1). How does it appear to you, as dirt, minerals, or soil? At first glance it may appear very ordinary, something that you routinely take for granted. However, if we make a closer inspection, we find that soil is far from ordinary. It is the home of countless numbers of organisms, both easily visible and microscopic. The soil acts as the Earth’s recycler, filter, purifier, and storehouse. The soil ecosystem recycles dead organisms into the building blocks of new life, it transforms toxic substances into simple compounds, it renders pathogenic organisms harmless, and it purifies and stores water as it passes through. The soil is a dynamic living system which functions as the interface between land and sky, and the living and the dead. Soil is the repository of fertility and life on this planet. Even as the nature and properties of the soil vary greatly by location, its role in ecosystems and the ways in which it functions are basically constant from one place to another worldwide.

This lesson will introduce you to the basic functions performed by all soils, consider environmental and cultural factors that enhance or degrade it’s ability to perform these functions, and address regional similarities and differences in soil type and quality on a global scale.

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This lesson was developed by Martha Mamo, Timothy Kettler, and Dennis McCallister at the University of Nebraska-Lincoln; Jim Ippolito at Colorado State University; Ron Reuter at Oregon State University; Christoph Geiss at Trinity College-Connecticut; and William Zanner at the University of Minnesota. Development of this lesson was supported by the National Science Foundation Course, Curriculum, and Laboratory Improvement Program (NSF-CCLI), Award Number DUE-0042603. Any opinions, findings, conclusions or recommendations expressed in this publication are those of the author(s) and do not necessarily reflect the view of NSF.