Understanding Soil Change :
Soil Sustainability over Millennia, Centuries, and Decades

Daniel D. Richter Jr, Daniel Markewitz,
Foreword by William A. Reiners, Pedro Sanchez

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Book Description:

Across the world, soils are managed with an intensity and at a geographic scale never before attempted, yet we know remarkably little about how and why managed soils change through time. Understanding Soil Change explores a legacy of soil change in southeastern North America, a region of global ecologic, agricultural, and forestry significance: from the acidic soils of primary hardwood forests that covered the region until about 1800, through the marked transformations affected by long-cultivated cotton, to contemporary soils of rapidly growing and intensively managed pine forests. These well documented records significantly enrich the science of ecology and pedology, and provide valuable lessons for land management throughout the world. The book calls for the establishment of a global network of soil-ecosystem studies, like the invaluable Calhoun study on which the book is based, to provide further information on sustainable land management, vital as human demands on soil continue to increase.

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The Authors:

Daniel D. Richter, Jr. is Professor of Soils and Forest Ecology and Co-Director of the Southern Center for Sustainable Forests.

Daniel Markewitz is Assistant Professor at the Warnell School of Forest Resources at the University of Georgia.

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Advance praise for this book:

'It is a grand tour of soil change at different temporal scales, done with elegance and scientific rigor. This story will be of interest to ecologists who have never had a soil science course, as well as to advanced pedologists, biogeochemists, agronomists, foresters, and land managers.'

-William Reiners and Pedro Sanchez

Forward

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Forward:

William A. Reiners and Pedro A. Sanchez, June 2000

Historical effects often underlie otherwise puzzling observations in nature so that history is an essential element for understanding the ecological status of a place. Similarly, a historical perspective is essential for understanding soils. The great pedologist, Hans Jenny, made "time" one of a series of variables determining the state of particular soils. Ecology and soil science are parallel sciences in many ways, as well as being inextricably linked through reciprocal relationships between biota and soil condition.

Both soil scientists and ecologists seek to interpret the immediate state of ecosystems and soils (the latter considered part of the former by ecologists) through historical perspectives. For example, ecologists will attempt to understand the regrowth of a logged forest as a short-term phenomenon-in the perspective of longer term phenomena of primary succession, climate change over the span of thousands of years, migration of species, and changing status of soils. The experienced ecologist attempts to interpret vegetation dynamics in the context of soil change, but usually assumes, sometimes erroneously, that vegetation and other parts of the ecosystem's biota change more rapidly than do the underlying soils. Soil scientists are taught soil genesis in a theoretical way, but most practice their profession at time scales too short to expect changes in soil formation.

Few cases exist for understanding the long-term process of soil development. The patterns of long-term change are known from the Mendocino Terraces of California, formerly glaciated terrain of Glacier Bay, Alaska, dunal terrain around Lake Michigan, and volcanic flows of Hawaii. These documented examples provide benchmarks by which we have gained insight into long-term soil development and its ecological implications. Likewise long-term agronomic research spanning decades to over one century, notably Rothamsted in the UK, Illinois' Morrow plots and shorter, but decadal ones in the tropics, have provided valuable knowledge about the chemical and physical dynamics of soils and plant growth.

Richter and Markewitz open up another such example with their sweeping treatise of the Ultisols of the southeastern U.S. They give us another benchmark example for a large region having very high agricultural and forestry significance. Building on the work of earlier scientists from decades ago, Richter and Markewitz examine soil change on the South Carolina Piedmont on multiple temporal scales: decades, centuries and millennia. The authors carefully guide us through two interacting strands of historical narrative: pedogenesis of the old, geomorphologically stable, uplands of the southeastern Piedmont, and land use change on the Old Ray Place, Union Co., South Carolina. The combination of these two narratives builds a fascinating story of interaction between land use and soil condition. It also leads to some important conclusions about the consequences of industrial forestry. Erosion, weathering, leaching, translocation, planters, slaves, tenant farmers and modern foresters all play roles in this dual saga of the old South.

This work is also of extreme importance to the tropics, even though South Carolina lies squarely in the warm temperate region. Ultisols and related soils cover vast areas of the tropics with similarly low inherent fertility, coarse-textured surface soils and low-activity clays. For example, the main difference between most Ultisols of the study area and similarly classified ones in the tropics is the different soil temperature regime. In addition, there are strong linkages in the human influence. The history described by Richter and Markewitz is a classic saga of shifting cultivation, which was the first agricultural system in forested areas of the United States and Europe and the prevalent system nowadays in the humid tropics, most of it on Ultisols. While few places in the tropics have gone through such a stage of agricultural intensification as has the southeastern United States, resulting in this case in millions of hectares of productive secondary forests, this book provides valuable insights on the processes involved in the transformation of slash and burn agriculture into a modern rural landscape where farms are scattered in a landscape dominated by forests, which is typical of much of today's South.

Building on the long-term observations of earlier scientists, these authors show how Ultisols, a very important soil order worldwide, come into being through natural weathering, leaching and accumulation processes. They then discuss data on the impacts of forest clearing, mixed crop and cotton farming, liming and fertilization on these old soils. Finally, they evaluate the impacts of pine forest growth on these old fields. The results are impressive and sometimes surprising.

This story comes to us as a result of long term observations and systematic sampling, analyses and archiving. Unfortunately, such sustained observations are rare in the world and we must be grateful to the authors for synthesizing the data in such a palatable form. In the same vein, the authors issue a challenge to all of us. While espousing the value of synthesized, long term studies like this, they ask why such efforts should be so rare, and whether we as a modern society concerned about long-term sustainability can commit to expansion of these scientific activities more broadly. They make a strong case for institutionalizing long-term studies at Calhoun Experimental Forest where these records were made, and for representative sites at different biomes and major soil orders elsewhere in the world.