Soil Microbiology by Tate Robert L. III;

Author:Tate, Robert L., III; [Tate, Robert L.]
Language: eng
Format: epub
ISBN: 9780470311103
Publisher: Wiley
Published: 2020-10-28T00:00:00+00:00

9

Introduction to the Biogeochemical Cycles

Consider a handful of soil. Most soils (i.e. mineral soils) generally have the look and feel of a complex mixture of mineral particles; that is, they are composed of a reasonably simple mixture of sand, silt, and clay. This observation could easily lead to the conclusion that soil is simply a mixture of mineral particulates. Perhaps we might also conclude that variability in soil function could be derived, at least in part, from differences in chemical composition and particulate size. A bit more contemplation could lead to the conclusion that the role of soil in the ecosystem only extends to the properties associated with providing physical support for plants and directing water and air to plant roots. Over the millennia, we have come to appreciate the fact that the easily seen soil components are closely associated with myriad organic compounds and living organisms ranging from nano‐sized bacteria and viruses to easily recognized higher animal and plant life. Complex biogeochemical cycles of life requiring minerals and mineralization of decaying biomass provide the energy and nutrients required for growth of the soil biological community. Thus, this chapter has the objectives of examining the relationships held in common by organisms producing the nutrients and the processes used in their study.

As our examination of soil properties extends beyond our initial observations of the complexity of the physical structure, we must ask the simple question “Why is such complexity in structure necessary?” The answer to this query relies on considerations beyond examination of individual soil minerals. The role of soil in relationship to the function (existence) of the total ecosystem must be considered. A good starting point could be the contributions of soil to plant community growth and development. Clearly, soil must provide a physical support for plants as well as containing the basic elements required for plant growth. Some initial conclusions regarding soil structure and variability include the following.

The nutrient needs of the plants change throughout the growing season.

Temperature in the soil change daily.

Soil moisture is highly variable.

Growth of the plant changes soil chemical and physical properties.

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