A number of North American Indigenous languages include some words that require a paragraph to fully translate them. Such words are often associated with nature and natural occurrences because the lives of the indigenous people were so closely intertwined with nature, nature of which they saw themselves a part.

Merriam-Webster’s Thesaurus lists synonyms for soil as dirt, dust, ground, island, and continent among others. But none of these is really sufficient.

Soil is the complex unconsolidated outer layer of land that includes organic matter and is essential to plant growth. This chapter will reveal that the word “soil” is like the indigenous words described above, with a paragraph necessary to capture its full essence. And research continues to expand this paragraph as it uncovers previously unknown features of this essential resource that is too often taken for granted. For example, researchers have begun to consider organism sounds in soil and soil noise pollution fields worth investigating for agricultural applications.

Pie chart showing components of soil as about 50% pore space, half air-filled and half water-filled; about 50% Soil solids, with the majority of that being inorganic mineral components.
Figure 13.1.1. The major components of soil: inorganic minerals, organic matter, water, and air.
Relative percentages of soil components:
  • Water, about 25 percent of the soil volume, in pore spaces
  • Air, about 25 percent of the soil volume, in pore spaces
  • Inorganic mineral matter, about 40 to 45 percent of the soil volume                                                      The mineral content of soils is variable but is dominated by clay minerals and quartz, along with minor amounts of feldspar and small fragments of rock.
  • Organic matter, or “humus,” about 5 percent of the soil volume                                                      This includes both living and dead organisms.

Actual percentages depend on the amount of vegetation in the environment, available water, and soil compaction. A healthy soil is one that contains these components in amounts that will support plant life.


Learning Objectives

After reading this chapter, you should be able to…

  • List and summarize the roles of the factors involved in soil formation.
  • Describe the importance of soil and its status as a natural resource.
  • Explain how soil texture is determined and is used to classify soils.
  • Explain the role of biological soil crusts in arid environments.
  • Discuss soil’s potential in climate change mitigation. 




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Dynamic Planet: Exploring Geological Disasters and Environmental Change Copyright © 2021 by Charlene Estrada, Carolina Michele Londono, Merry Wilson is licensed under a Creative Commons Attribution-NonCommercial-ShareAlike 4.0 International License, except where otherwise noted.

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