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Soil Survey Objectives and Pilot Projects for Measuring Soil Change

Arlene J. Tugel1, Karl Hipple2, Chris Smith3, Susan Andrews4, and Jeffery E. Herrick5

1Soil Scientist, NRCS, Liaison to ARS Jornada Experimental RangeLas Cruces, NM; 2National Leader for Soil Survey Interpretations, NRCS, Lincoln, NE,

3National Leader for Technical Soil Services, NRCS, Washington, DC; and

4Soil Quality National Technology Development Team Leader, NRCS, Greensborough, NC.

5Research Soil Scientist, ARS Jornada Experimental RangeLas Cruces, NM

presented at NCSS Conference, Madison WI, June 4-8, 2007

Introduction

Human impacts on soil have garnered increased attention by policy makers, producers, and users of soil survey information. Currently, soil survey applies two conventions to address changes in soil properties resulting from land use and management. These conventions are 1) taxonomic classes for drastically altered soils and 2) phase distinctions for soils with a relatively unaltered control section. A third convention using simple conceptual models of change is proposed to illustrate dynamic management effects on soils (Tugel et al., 2005). This reportidentifies soil survey objectives for soil change, dynamic soil properties, and management effects on soil; provides a status report on pilot studies and the sampling guide for dynamic soil properties;describes the current NRCS implementation strategy;and presents suggestions for NCSS Cooperator involvement in this aspect of the new soil survey.

Soil survey objectives

The NRCS Soil Change Leadership Team is comprised of Karl Hipple, National Leader for Soil Survey Interpretations, Arlene Tugel, Soil Scientist-Liaison to ARS, Chris Smith, National Leader for Technical Soil Services, and Susan Andrews, Soil Quality National Technology Development Team Leader. The current soil survey program objectives for soil change and dynamic soil properties are broad enough to be relevant over the long term, although others may need to be added. The objectives are as follows:

  1. Soil change information. Account for soil change over the human time scale.
  2. Data quality. Refine existing soil survey data (aggregated data) to improve accuracy.
  3. Interpretations.Develop interpretations of land use and management effects on soil function.
  4. Landscape scale processes. Address soil processes related to soil function at the landscape scale.

Meeting the four objectives will provide information needed to maintain high quality soils, a productive landscape, and a healthy environment.Dynamic soil property data and interpretations will be used a number of ways. For instance, products can be developed for conservation planners, resource managers, and programs to show benefits of conservation systems and aid in practice design.Additionally, information on resistance, resilience and thresholds can be used to identify and protect lands at risk of irreversible change (e.g., erosion, loss of mineral CEC, salinization, contaminants). This new soil survey information will be used to support sustainable management ofsoil quality, soil functions, and ecosystem services.

Sampling guide and pilot studies

The development of new protocols for use in soil survey maintenance and update activities is underway. A cooperative effort to develop sampling guidelines was initiated in 2004. NRCS is developing the guidelines in cooperation with the AgriculturalResearchServiceJornadaExperimentalRange, National Park Service, Forest Service and Bureau of Land Management. A draft of the “Guide for Sampling Dynamic Soil Properties” has been reviewed by internal and external reviewers and is currently undergoing revision.

The procedure for data collection uses replicated comparison studies, not monitoring. Although not covered in the current Guide, short-interval monitoring can be conducted to document daily, seasonal, or annual cycles and variation. Short-term temporal variation is an important consideration for selecting and properly observing dynamic soil properties in comparison studies. Our goal of documenting long-term (decades to centuries) soil change in soil survey will be accomplished through comparison sampling based on a conceptual model of how soils change. Modeling will eventually be used to extend the data to other similar soils. Monitoring for long-term changes in resource condition is an alternative, but it could take decades or centuries.

Four pilot studies have been conducted to help craft, test and refine sampling protocols. The pilots that are completed or underway include Big Bend National Park (TX, 2002-2004); Arches National Park (UT, 2005-2006); Springfield Plateau (MO, 2006-2007); and Northern Idaho (ID, 2006-2007). Plans are underway to initiate a pilot project on cropland late in FY07. Soils sampled include benchmark soils or other extensive soils. The general scheme for sampling is as follows:

  1. Use a simple conceptual model such as a state and transition model (Stringham et al., 2003) to describe management systems and hypothesized causes and effects of change.
  2. Use management systems or plant communities to stratify (subdivide) the soil map unit component.
  3. As a comparison study, sample two or more different management systems (states or phases of a state).
  4. Integrate data collection for soil, vegetation/management.
  5. Document reference condition (e.g., inherent potential or enhanced condition).
  6. Substitute space-for-time to analyze change (Pickett, 1989).

Field staff perspectives on efficiency, ease of implementation, and relevance to data requirements for resource management are also considered in the evaluation of pilot studies (Scott et al., 2006).

NRCS implementation strategy

Once the pilots are completed, NRCS plans to move forward with a trial implementation in one or two MLRA soil survey offices. Work will begin with benchmark soils and build upon existing data. The dynamic soil property data will be stored as point data and models will eventually be used to populate the aggregated database. The sampling protocols will be readjusted iteratively as we learn more.

Suggestions for NCSS roles and actions

The NCSS has a history of beneficial contributions to soil science and soil survey through effective cooperation. These contributions include advances in soil classification and mapping, soil interpretations, and landscape analysis. Soil change is another new and exciting challenge for the organization to help meet customer needs. Each member of NCSS has a role to play, whether it be through committee work, research, education, or building partnerships outside the NCSS. Suggested actions include:

  1. Identify agency or institutional business requirements for information about how soils change. These may relate to resource threats such as global warming, biofuels, hypoxia, bioterrorism, wildfire, or invasive weeds. Specific needs should be described for recent and emerging national programs such as green-house gas reductions, carbon credits, sustainable development, soil quality, rangeland health, and watershed risk assessments. Specific needs for traditional programs such as natural resources monitoring, planning, and practice selection and design should also be described.
  2. Synthesize agency requirements and academic vision to develop reports that will help agencies and institutions with program planning. An example is a ‘Needs and availability report for dynamic soil properties and other data related to human impacts on soil’.
  3. Cultivate a collective vision for soil change in soil survey and identify ways to build employee capacity to fulfill the vision.
  4. Develop educational curricula for soil change and human impacts on soil.
  5. Write a comprehensive research agenda for journal publication.
  6. Explore existing and potential funding sources for research on soil change. Work with granting program managers to include soil change and human impacts on soil as new research objectives.
  7. Conduct research and technology development projects.

While there are numerous research needs related to dynamic soil property data collection and interpretation, three are crucial at this time. Some of these can be met through existing data while others may require new research. Full completion of the Guidehinges on the following needs:

  1. Dynamic soil properties selected for sampled must be functionally important and cost-effective to measure (Figure 1). Information on relationships between property and function as well as simple field methods for measuring the properties is needed. This can be carried out through research, expert opinion, or literature reviews. The results will be incorporated in the Guide.
  2. Scientifically credible sampling procedures depend on knowledge of the spatial and temporal variability of near surface dynamic soil properties. Existing or new data needs to be summarized to determine soil property spatial variability at multiple landscape scales. The information will be used to develop recommended sample designs for a variety of soil-landscape management types and incorporated into the Guide.
  3. New function-based interpretations are needed to support monitoring, assessment, and management of human impacts on soil. In particular, procedures are needed to quantify or predict human impacts on soil functions/services such as hydrologic functions, nutrient cycling, and providing a stable medium for plant growth.Related new soil survey products may include tools for selection of suitable indicators and their reference values as well as interpretations for threshold values, resistance, resilience and rates of change.


Figure 1. Dynamic soil property selection should be based on function, measurable differences, and cost.

Summary

Soil change data and interpretations will help land managers and decision makers balance their goals for production, economics, sustainability, and the environment. Today, soil change on the human time scale is an emerging concept for soil survey that requires NCSS collaboration for a successful program.As the new soil survey moves forward, dynamic soil property data and interpretations relating to human impacts on soil function will add value to update and maintenance products. Documentation oflong-term soil change in soil survey will be accomplished through comparison sampling based on a conceptual model of how soils change. Modeling will eventually be used to extend data to other similar soils.Many opportunities exist for the National Cooperative Soil Survey to collaborate on these efforts.

References

Pickett, S.T.A. 1989. Space-for-time substitution as an alternative to long-term studies. p. 110-135. In G.E. Likens (ed.) Long-term studies in ecology: Approaches and alternatives. Springer-Verlag, New York.

Scott, C., A.J. Tugel,D. Truman, J. P. Ward,V. Parslow, P. Biggam, B. Fitzsimons, C. Seybold. 2006. Dynamic soil properties and the soil survey – Pilot project in ArchesNational Park, 2005. Paper. In Proceedings of the Western Regional Cooperative Soil Survey and Western Society of Soil Science 2006 Conferences. June 19-23, 2006.Park City, UT. Available online

Tugel, A.T., J.E. Herrick, J.R. Brown, M.J. Mausbach, W. Puckett, and K. Hipple. 2005. Soil change, soil survey, and resource decision making: A blueprint for action. Soil Sci. Soc. Am. J. 69:738-747.