Published online 28 June 2005
Published in Soil Sci Soc Am J 69:1351-1353 (2005)
DOI: 10.2136/sssaj2005.0063
© 2005 Soil Science Society of America
677 S. Segoe Rd., Madison, WI 53711 USA
Comments and Letters to the Editor
Letter to the Editor on "From the Earth's Critical Zone to Mars Exploration
Can Soil Science Enter Its Golden Age?"
Henry Lin
Department of Crop and Soil Sciences 116 A.S.I. Building The Pennsylvania State University University Park, PA 16802
henrylin{at}psu.edu
Soil science research is undergoing significant changes, driven by new societal priorities, emerging technologies, and a better understanding of natural systems and anthropogenic impacts. Recent publication of a special issue of Science on "Soils—The Final Frontier" (11 June 2004) and two other special issues on the remarkable success of Mars Exploratory Rover mission—"Spirit at Gusev Crater" (6 Aug. 2004) and "Opportunity at Meridiani Planum" (3 Dec. 2004)—were timely and encouraging. However, as Sugden et al. (2004) pointed out—over 500 yr after Leonardo Da Vinci—the ground beneath our feet is still as alien as a distant planet. I therefore wish to express some perspectives on the future of soil science in this letter, and would like to call on the public to embrace soil science in the broadest sense and to urge fellow soil scientists to unite as a community to address "big" science questions.
While best known for its role in providing water and nutrients to sustain agriculture and ecosystems, the soil indeed plays diverse critical roles in sustaining life, the environment, and society. Thus, an inclusive vision for integrative soil science should encompass "7 + 1" roles from the earth's critical zone to extraterrestrial explorations, as portrayed in Fig. 1 . I believe it is time to embrace soil science as a science in the broadest sense and to move beyond current fragmentation. Soil is a natural integrator of the "7 + 1" functions, providing a central link to multiscale interdisciplinary integration for studying the earth's critical zone.
The earth's critical zone concept (Nation Research Council [NRC], 2001a) provides an appealing framework for integrated studies of soil with water, air, rock, and biotic resources in the earth's surface and near-surface environments. Interactions at these interfaces between the solid earth and its fluid envelopes determine the availability of nearly every life-sustaining resource (NRC, 2001a). Hence, the National Research Council has identified the integrated studies of the earth's critical zone as one of the most compelling research areas in the 21st century. Moreover, I believe knowledge of the soil and its forming processes pose unique contributions to extraterrestrial explorations in search of water and life and for developing advanced life support systems used in space exploration. Although some might argue that Martian soils (and other planetary surface materials) may not be called "soils" because biological processes have not yet been confirmed, early stages of soil formation and subsurface pedogenesis do not always require a biological factor (e.g., Ugolini and Edmonds, 1983). As the amazing Spirit and Opportunity are continuing the exciting exploration for signs of water on Mars through investigations on soils, rocks, and landforms, answers to the fundamental question of how the weathering engine on Mars has transformed the protolith into various soils would likely shed light on the role of water (and other soil-forming factors such as climate) in the genesis of Martian soils.
Historically, soil science has followed a circuitous path in its evolution from a discipline with roots in geology, to an applied agricultural and environmental discipline, and now to a bio- and geoscience with a focus on the earth's critical zone (Wilding and Lin, 2005). This closes the loop, but along the way soil science has become more extensive and comprehensive. I believe soil science can enter its golden age through vigorous integration of its expertise with other bio- and geosciences. Such integration will significantly increase public understanding as well as advance soil science.
For example, synergies can be generated if soil science is adequately integrated into the science and infrastructure initiatives of the Consortium of Universities for the Advancement of Hydrologic Sciences, Inc. (CUAHSI), a NSF-sponsored and community-based organization. A number of recent NRC reports have already highlighted the significance of integrated soil and water studies in the context of agriculture (NRC, 1993a, 1997), groundwater vulnerability (NRC, 1993b), watershed management (NRC, 1999), earth sciences (NRC, 2001a), water resources (NRC, 2001b), and environmental sciences (NRC, 2001c). It is worth mentioning that all of the eight Grand Environmental Challenges identified by the NRC (2001c) are directly or indirectly related to soil and water resources, especially in the areas of land-use dynamics, hydrologic forecasting, biogeochemical cycles, climate variability, and ecosystem functioning.
Another example of synergistic advancement of soil science lies in the interface with biogeochemistry. The recent formation of the Weathering System Science Consortium (WSSC) calls for answers to the fundamental scientific question regarding the earth's weathering processes under the influence of climatic, tectonic, and anthropogenic forces (Anderson et al., 2004). Pedogenesis is essentially an integrated weathering phenomenon that results from a series of physical, chemical, and biological processes over time. It provides a holistic view and valuable historical record of the processes that occurred, or are occurring, in the earth's critical zone (or in other planetary surfaces). Biogeochemical cycles are inseparable from the hydrologic cycle and the critical reservoir of the soil, thus indicating the fundamental importance of integrated studies for the fluxes of water, energy, and chemical elements.
Soils have many other significant roles to play in various emerging national and international environmental networks designed to address "big" science questions that are increasingly called for by funding agencies and various scientific consortia. In NSF alone, planning is underway to establish the National Ecological Observatory Network (NEON), the National Hydrologic Observatory (HO) Network, and the Collaborative Large-scale Engineering Assessment Network for Environmental Research (CLENER). At the international level, coordinated efforts such as the Earth System Science Partnership (including IGBP, IHDP, WCRP, and DIVERSITAS), the Global Climate Observing System (GCOS), and the Integrated Global Observing Strategy (IGOS) have attracted considerable interest. It is apparent that there are ample opportunities for soil scientists to contribute in a variety of "7 + 1" functions that are of importance to society.
To stimulate discussions on how best to embrace soil science in the broadest sense, to debate how to unite ourselves to address "big" science questions, and to instill in the public an appreciation of the soil as a precious gift from nature, I would like to highlight three actions that could help propel soil science into its golden age:
- Get involved: An inclusive and integrative soil science requires that our door be opened to non-traditional clientele and that we enter through the doors of other communities. Soil science community should promote further interactions and collaborations with all relevant scientific societies (including social and economic sciences). This will only strengthen our profession, and help gain sustainable future growth and legitimate support. To this end, an independent and neutral status of our soil science society will be more attractive to non-agricultural professionals. The definition of "soil" may also be broadened to reflect soil scientists' sphere of interest that includes the whole regolith and the earth's critical zone. But, regardless of how we broaden the domain of our interest, our unique aspects remain (such as pedogenesis and soil-forming theory). To create true cooperation and interchange in the interdisciplinary arena, we also need to adopt a joint learning trajectory and the salesman principle to effectively help formulate environmental regulations and policies (Bouma, 2005). Scientists playing such a role should be prepared to invest time, creativity, and energy to establish such communication.
- Come together: Subdisciplines of soil science need to be integrated to address "big" science questions. Soil scientists, however, tend to use entities for research that are less well defined and procedures that are less integrated, based often on the ability or feasibility to measure, rather than on fundamental differences in integrated physical, chemical, and biological processes (e.g., Lin et al., 2005). We should strive to unite ourselves on several fronts, including: (1) Formulating "big" science questions that can lead to major breakthroughs. As an example, a fundamental question in unsaturated zone flow and transport is: "How to predict flow paths and patterns in heterogeneous and structured in situ soils across spatial and temporal scales"? (2) Developing integrated databases and models that are consistent and interoperable. For instance, there is currently no concerted effort for a national database that addresses the spatial distribution and temporal dynamics of soil hydraulic properties, geochemical elements, and biotic communities; (3) Coordinating shared facilities and tools to provide an infrastructure for long-term systematic data collections and synthesis using distributed field observatories and sensor networks. It is amazing that, while large-scale observing networks have been or are being established for atmosphere, biosphere, lithosphere, and hydrosphere, such a network for the pedosphere (or the earth's critical zone as a whole) is lacking.
- Educate the public: To effectively communicate the "7 + 1" roles of the soil, education and outreach are needed at all levels, from grade schools to policy forums. This issue is critically linked to many challenges we have been facing, including student enrollment, future workforce, research funding, public perception, and land and water ethic. Ongoing efforts to establish the Smithsonian soils exhibit are expected to have far-reaching impacts, but we need to do much more. The following examples illustrate the point: (1) If elevated attention to aerosols can be effectively linked to climate change, why can't we attractively convey the "secret and magic" of soil and water in sustaining life and civilization on this blue planet? Soil and water as complex environmental systems are as worthy of study as the heavens and the oceans; (2) Amidst the vast number and variety of microorganisms in the soil (one heaping tablespoon of soil may contain up to 10 billion microbes—one and a half times the human population on earth) are a host of microbes now valued for their potential to help solve environmental problems as well as supply cures for diseases (including botulism and anthrax) (Singer, 2003); (3) Soil scientists need to proactively involve in land-use decisions and "smart growth" planning. New land-use plans and land development practices should consider the manner in which natural soils vary over the landscape, which offers clues as to "what" can best be done and "where" with the lowest risks and the greatest opportunities.
In closing, the soil is the essence of the earth's critical zone. It contributes to the origin and development of life on this planet, the rise and decline of human civilizations, and the sustainability or deterioration of global ecosystems. Water flux into and through the soil in the landscape resembles the way blood circulates in a human body. Soil and water combined thus create the foundation that sustains the earth's ecosystems and human society, bearing direct impacts on a variety of societal and environmental concerns. We need to be constantly reminded that a broken geoderma cannot be left uncured and that "Our own civilization is now being tested in regard to its management of water as well as soil" (Hillel, 1991). A call for embracing soil science in the broadest sense and for uniting soil scientists as a viable community will pave the way for soil science to enter its golden age.
REFERENCES
- Anderson, S.P., J. Blum, S.L. Brantley, O. Chadwick, J. Chorover, L.A. Derry, J.I. Drever, J.G. Hering, J.W. Kirchner, L.R. Kump, D. Richter, and A.F. White. 2004. Proposed initiative would study Earth's weathering engine. EOS 85:265–269.
- Bouma, J. 2005. Hydropedology as a powerful tool to environmental policy research. Geoderma (in press).
- Hillel, D. 1991. Out of the earth—Civilization and the life of the soil. The Free Press, New York.
- Lin, H.S., J. Bouma, and Y. Pachepsky. (ed.) 2005. Hydropedology: Bridging disciplines, scales, and data. Geoderma special issue, Elsevier. (In press).
- NRC. 1993a. Soil and water quality: An agenda for agriculture. National Academy Press, Washington, DC.
- NRC. 1993b. Ground water vulnerability assessment—Contamination potential under conditions of uncertainty. National Academy Press, Washington, DC.
- NRC. 1997. Precision agriculture in the 21st century. National Academy Press, Washington, DC.
- NRC. 1999. New strategies for America's watersheds. National Academy Press, Washington, DC.
- NRC. 2001a. Basic research opportunities in earth science. National Academy Press, Washington, DC.
- NRC. 2001b. Envisioning the agenda for water resources research in the twenty-first century. National Academy Press, Washington, DC.
- NRC. 2001c. Grand challenges in environmental sciences. National Academy Press, Washington, DC.
- Singer, M. J. 2003. Soil science. Geotimes. July 2003.
- Sugden, A., R. Stone, and C. Ash. 2004. Ecology in the underworld. Science (Washington, DC) 304:1613.[Abstract]
- Ugolini, F.C., and R.L. Edmonds. 1983. Soil biology. p. 193–231. In L. P. Wilding et al. (ed.) Pedogenesis and soil taxonomy. I. Concepts and interactions. Elsevier, Amsterdam, The Netherlands.
- Wilding, L.P., and H.S. Lin. 2005. Advancing the frontiers of soil science towards a geoscience. Geoderma (in press).
