[EBOOK] SOIL ORGANIC MATTER IN SUSTAINABLE AGRICULTURE, Edited by Fred Magdoff and Ray R. Weil, Published by CRC PRESS

During the past two centuries, scientists, farmers, and agricultural educators have tended to alternate their views of soil organic matter (SOM) between the extremes of great appreciation and low esteem. As an early 20th century bulletin explained, organic matter was “once extolled as the essential soil ingredient, the bright particular star in the firmament of the plant grower...” before it “.fell like Lucifer.” as a result of the findings of 19th century agricultural chemists that most of the plant structure (C, that is) originated in the atmosphere (Hills et al., 1908). In the early 20th century, soil organic matter was once again viewed as critically important, only to become considered close to irrelevant to agriculture following the availability of cheap fertilizers, especially N, following World War II.

The paradigm of industrial agriculture — which developed following World War II and continues even now to dominate agriculture — views soil and plant constraints that arise while growing crops as individual problems that are usually considered to be unrelated to one another. The industrial agriculture mindset believes the best way to deal with these individual problems is to try to resolve each one separately. The remedies, according to this view, lie in the application of specific (usually purchased) inputs: fertilizers and lime for soils low in nutrients; pesticides for crops threatened by diseases, nematodes, insects, and weeds; extra irrigation water for soils with declining water holding capacity; deep tillage for overly compacted soils, etc. The development, promotion, and implementation of the industrial agriculture model has been facilitated by the specialized training that many agricultural scientists and extension specialists receive — causing them to concentrate efforts in their disciplines (and frequently subdisciplines) with little ongoing active professional engagement with those in other disciplines.

A renewed appreciation of soil organic matter — in all its astonishing complexity — began toward the end of the 20th century and continues to this day. Scientists have come to appreciate SOM’s profound influence on almost all soil properties — such as structure (and hence on water infiltration and storage, susceptibility to surface runoff and erosion), cation exchange capacity, nutrient availability, buffering (pH, nutrient availability), color, and plant pest pressure. Additionally, new tools have become available to help explore SOM’s chemical and physical properties as well as the diversity of soil life. With its critical role in so many soil properties and processes, organic matter can provide an integrating concept for understanding and promoting soil health and soil quality. Viewing healthy (high quality) soils as a major goal fosters a whole-system, preventive approach to agricultural management. In contrast to the industrial model, this approach aims to enhance soil properties so as to make the field ecosystem more self regulating, self sufficient, resistant to degradation, and resilient. Rather than look for post-facto “band-aid” solutions, the preventive approach emphasizes management to prevent chemical, biological (pest), and physical problems from developing in the first place.

In addition to an immense volume of scientific journal articles dealing with SOM, a number of books have been published over the last decade that deal with both scientific and practical aspects of SOM management. In this book, we have brought together scientific reviews concerning issues that are key for practical SOM management. We have included evaluations of the various types of organic constituents in the soil — the living organisms, the relatively fresh residues, and well decomposed substances (for which we have reserved the use of the term humus). The health (quality) of a soil is strongly and positively affected by soil organic matter (Weil and Magdoff, Chapter 1) and the various practices that enhance SOM (Magdoff and Weil, Chapter 2). There are chapters that focus on the effects of soil and crop management practices on soil organisms (Kennedy et al.,Chapter 10) and organic matter gains and losses and the significance of various SOM fractions (Franzluebbers, Chapter 8; Wander, Chapter 3; Chen et al., Chapter 4). Chapters also discuss the contributions to soil quality and crop growth by fungi (Nichols and Wright, Chapter 6) and earthworms (Edwards and Arancon, Chapter 11).

Soil organic matter and its management to promote soil health goes hand-in-hand with the emergence of an ecologically based approach to soil and crop management that stresses prevention of imbalances leading to soil and crop problems down the road (Magdoff and Weil, Chapter 2). This approach is especially apparent with regard to the role of SOM and its management in the development of soils suppressive to plant diseases (Stone et al., Chapter 5) and the relation of SOM management to supplying nutrients to crops (Seiter and Horwath, Chapter 9). It also recognizes the potential effects arising from the interactions between belowground food webs (based on SOM and its management) and aboveground food webs that influence crop health and productivity (Phelan, Chapter 7).

We hope this book will provide essential scientific background and pose challenging questions relevant to both scientists and students as they strive to better understand SOM and develop improved soil and crop management systems.

[EBOOK] SOIL ORGANIC MATTER IN SUSTAINABLE AGRICULTURE, Edited by Fred Magdoff and Ray R. Weil, Published by CRC PRESS

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