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Dept. of Crop and Soil Sciences Washington State University 243 Johnson Hall Pullman, WA 99163
kcherrey{at}wsu.edu
MILO I. HARPSTEAD, THOMAS J. SAUER, and WILLIAM F. BENNETT. Illustrated by MARY C. BRATZ. Iowa State University Press, 2121 South State Avenue, Ames, Iowa 50014. 2001. Hardback, 225 p. $44.95. ISBN 0-8138-2942-9.
The first edition of this book was published in 1980. The second edition was published eight years later and the third edition was recently published in 1997. Soil physicist Thomas J. Sauer replaced Francis D. Hole as the second author starting with the third edition. Soil fertility and management were expanded in the second edition. Primarily, soil water, soil temperature, and soil engineering were revised in the third edition. Despite only four years between the third and fourth editions, the fourth edition is an extensive revision.
This book is easily accessible to both high school and beginning post-high school students. It will also benefit professionals outside of soil science who desire an easily accessible introduction to the basic principles of soil science. Soil scientists will find it a handy compendium of soil science concepts. Although a few concepts are too simplified, most are technically accurate. An annotated "References for Further Study" at the end of each chapter would greatly enhance the utility of this book.
Soil Science Simplified is profusely illustrated with line-art drawings by Mary C. Bratz. Her illustrations add greatly to the appeal of this book. The illustrations immediately grab one's attention and help one retain key concepts of soil science. In this edition, important terms are now set off in bold, and italics are used for added emphasis. Along with Bratz's illustrations, this makes skimming the book more rewarding.
There are 13 chapters in this edition. They appear as: The Soil Around Us, Soil Formation, Soil Physical Properties, Soil Biology, Soil Colloids and Chemistry, Soil Water, Soil Temperature and Heat Flow, Soil Fertility and Plant Nutrition, Soil Management, Soil Conservation, Soil Classification, Soil Surveys, and Soil Engineering. In the very brief first chapter a working definition of soil is given and some of the uses of soil are introduced. The stated aim of this book "is to explain the basic principles of soil science in a practical way." Surprisingly, the connection between the treatment of soil and sustainable civilizations is not immediately made. (One has to wait until the soil conservation chapter.) Books such as Soil Science Simplified that address a broad audience are uniquely positioned to help foster the concept of a sustainable land ethic. As soil scientists, we should do everything we can to help develop this concept and educate those involved in land use.
The authors appropriately begin their explanation of soil science with the geology behind soil formation. The essential features of soil formation are concisely and accurately established. Because of their permanence and the difficulty in controlling them, soil physical properties are next introduced as those soil properties that should receive the greatest attention during land-use planning. Soil texture and structure, porosity and density, consistence, and color are condensed to the essentials.
Soil biology is introduced in Chapter 4. Here the reader is given a simplified account of the known roles played by microorganisms in the soil ecosystem. These microorganisms are said to provide important carbon sequestration and nitrogen cycling services. Interest in this branch of ecology has greatly increased during the last few years, and there is still so much we do not know. In this book, numerous management practices that may help sequester carbon are listed, but I did not get an appreciation of what we do not know. I was left wondering why the authors state "the net effect of increased atmospheric CO2 is not known, but it has been suggested that reduction of CO2 in the atmosphere would be ‘environmentally friendly.’" Practically all climate change scientists agree that CO2 levels in the atmosphere have dramatically increased since the beginning of the industrial era and that these higher levels of CO2 are responsible for increases in global temperature during this time. The debate is over the rate of future change.
The next chapter on soil colloids and chemistry includes more details on the clay fraction previously introduced. It is natural to combine colloids with soil chemistry since much of soil chemistry is governed by the ion exchange complex on clay-sized particles. Concise information in this chapter makes understanding of this difficult aspect of soil science easier. Soil chemistry concepts discussed involve clay structure, ion exchange, pH, base saturation, buffering capacity, acid and alkaline soils, and soil aggregation. The last three editions of this book state that 0.1 µm is commonly given as the upper limit to colloid diameter when it is really 1 µm. The important electrical double-layer is not adequately explained, but this is a minor issue for a book of this kind. (Again, an annotated "References for Further Study" would help.)
Soil physical properties involving water, temperature, and heat flow comprise the next two chapters. This edition has more description of energy budgets and an expanded irrigation section. There are elementary explanations of the hydrologic cycle, water budgets, plant water use, heat transfer processes, the factors affecting soil temperature, management of soil temperature, and the combined effects of water and temperature on soil bodies.
The soil fertility and plant nutrition chapter combines many of the previous concepts and relates them to plant requirements. Plant growth nutrients and techniques to gather soil samples for nutrient analysis are appropriately summarized. Precision farming is introduced as a means to more efficiently utilize fertilizers. There are very short sections on composting and organic farming methods. The authors do not address the long-term sustainability of conventional fertilizer use. They state, "Enough food could not be provided for the world's population if the plant nutrients for food crops were to be supplied solely from organic sources." Methane, a nonrenewable fossil fuel, is used in the Bosch-Haber process: 4N2 + 3CH4 + 6H2O 
8NH3 + 3CO3. Note that Fig. 8.9 illustrating this process in the book is missing the steam input.
The importance of soil physical condition in maintaining a healthy soil is again reiterated in the soil management chapter. Tillage practices are discussed at some length. This chapter also includes sections on the management of organic matter, soil pH, saline and sodic soils, and plant nutrients. An important but short section relates soil health to crop production practices appropriately adapted to local conditions. Logically, the soil conservation chapter follows next. Factors of soil erosion are explained as are techniques to minimize agriculturally induced erosion of a precious resource—soil. Curiously, the soil loss equation is not mentioned.
Reorganization of soil classification is particularly notable in this edition. The main features of the USDA 12-order, 1998 revision of soil taxonomy have been nicely condensed to 24 pages. Diagnostic epipedons and subsurface horizons are succinctly defined and made easily accessible to the lay reader. The 12 soil orders are summarized with just the right amount of detail for easy recall. The following chapter on soil surveys is similarly written.
The final chapter on soil engineering now includes a brief introduction to the soil classification schemes developed by engineers. Chapter sections discuss the relation of soils to dams, levees, roads, buildings, ponds, canals, recreational areas, and other structures. Important sections on reclamation and remediation of waste and disturbed lands are also included.
In summary, this book is a concise introduction to soil science. It strikes just the right balance of content, illustrations, and detail for students and professionals who desire a fast, accurate introduction to soil science. Soil scientists will find this book a handy compendium of soil science not readily summarized elsewhere in compact form. This book is only available in hardback; a more affordable paperback edition would help get this book into the hands of younger students for whom the sustainable use of soil is vitally important.
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