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June 1, 1996 E-mail: geotimes@agiweb.org

Unearthing the Mysteries of Soils

ALEXANDRIA, VA. A thin veneer of weathered rock and organic matter has had a profound influence on the Earth's history. Soils have helped change the gases of the atmosphere, altered the chemistry of ground water, and nourished life on this planet. In the June issue of GEOTIMES, soil scientists discuss strategies to improve their discipline -- a science governed by uncertainty and complex interactions.
In his article "Soil Science: Interdisciplinary by Necessity," Fred Miller argues that meeting societal demands will require an integrated effort by physicists, chemists, mineralogists, biologists, engineers, and other scientists. Interdisciplinary cooperation can develop models for sustainable ecosystem management and provide sound information for making decisions that affect public safety.
Predicting the behavior of water and chemicals in soils is an inexact science, too often used without regard to its inherent limitations. R.J. Wagenet's article, "Simulation Modeling: Predicting the Dynamics of a Soil's Unsaturated Zone," looks at the modeling techniques used to understand the region where water resides in partially-saturated soil pores. Spatial variability, pore size distribution, and the difficulty of collecting field data confound and challenge models and model users.
"We have long recognized that soil varies continuously rather than abruptly in most landscapes, yet models provide a rigid and discrete view of soil," explains Kevin McSweeney and John Norman in their article, "Soil Landscape Modeling: Issues of Scale." Models are helpful in refining basic understanding but are not useful for predicting changes occurring over a continuum of scale. New techniques such as digital terrain modeling and voxels (a 3-dimensional pixel) may improve spatial representation and provide models that help us make better use of the land.
In "Paleosols: Record and Engine of Past Global Change," Gregory Retallack shows how ancient soils provide clues about the atmospheric composition over the past 3.5 billion years. They recorded and fueled changes in levels of oxygen and carbon dioxide as plants and animals struggled for domination. "...Earth may have teetered from icehouse to greenhouse as first plants, then animals, gained the upper hand."
Coming in July ... GEOTIMES looks at wetlands -- vital but vanishing natural systems that keep surface water clean, control flooding, recharge groundwater, and provide homes to countless plant and animal species. Scientists examine efforts to slow the loss of wetlands in the United States and the tropics and look at the underlying geology of these ecosystems where land and water meet.

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