Friday, 14 July 2006 - 2:45 PM

Soil Quality Assessment: A Potential Policy Tool to Move beyond T.

Douglas L. Karlen1, Susan S. Andrews2, Ted M. Zobeck3, and Brian J. Wienhold1. (1) USDA-Agricultural Research Service (ARS), National Soil Tilth Laboratory, 2150 Pammel Dr., Ames, IA 50011, (2) USDA-Natural Resources Conservation Service (NRCS), ENTSC, 200 E. Northwood, Ste. 410, Greensboro, NC 27401, (3) USDA-ARS, 3810 4th St., Lubbock, TX 79415

The potential to use soil quality assessment as a conservation policy tool in the U.S. was first suggested by the U.S. National Academy of Science in their 1993 publication entitled Soil and Water Quality: An Agenda for Agriculture. During the past decade numerous research and education activities have been carried out to determine how to best define, measure, and interpret soil quality. These efforts have included the development of a soil quality test kit, fact sheets by the Natural Resources Conservation Service (NRCS), evaluations of several potential biological, chemical and physical soil quality indicators, and as a result numerous technical publications. Several scientific debates, book chapters, and review articles have also been devoted to the soil quality concept, because some within the U.S. soil science research community were concerned that such assessments could be misused despite good intentions among those favoring concept development. However, during this same period, U.S. conservation programs including the Conservation Security Program (CSP) and the Environmental Quality Incentives Program (EQIP) have begun to use potential soil quality impact to help prioritize applications for funding conservation practices. Currently, soil quality assessment in these programs is based on the Soil Conditioning Index (SCI), a tool used in conservation planning to estimate whether applied conservation practices will result in decreasing, stable, or increasing levels of soil organic matter (SOM). Use of the SCI is now required to be incompliance and receive financial assistance for practices such as the conservation crop rotation and residue management. This first step toward using soil quality assessment as a conservation policy tool is good, but focusing solely on a single indicator (soil carbon, organic matter or SOM) has raised concern among some producer and research groups including those using certifiable organic management practices, those farming soils with inherently low SOM levels, and researchers who have stressed the need to examine a suite of biological, chemical, and physical indicators to accurately assess soil quality. To address these concerns, the ARS is conducting cross-location research on a soil management assessment framework (SMAF) that uses scoring functions, adjusted for inherent soil and climatic conditions, to interpret and combine the various indicator measurements. The SMAF is being evaluated at Conservation Effects Assessment Project (CEAP) sites, at sites where long-term tillage and cropping systems studies have been run throughout the Great Plains, and at sites where the impact of harvesting crop residues as a source of biofuel or other bio-products are being quantified. The SMAF is also being tested for its ability to help interpret results of simulation models such as the Economic and Productivity Impact Calculator (EPIC). For the field studies, efforts are being made at each location to compare the SCI and SMAF results to determine how the tools compare and to help develop an effective soil quality assessment program for U.S. conservation policy. This presentation will focus on the evolution of the soil quality concept in the U.S. and its evaluation as a potential tool for assessing the conservation effects of agricultural practices.

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