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Erosion rates and annual soil loss tolerance (T) values in evaluations of soil management practices have served as focal points for soil quality (SQ) research and assessment programs for decades. Our objective is to enhance and extend current soil assessment efforts by presenting a framework for assessing the impact of soil management practices on soil function. The tool consists of three steps: indicator selection, indicator interpretation, and integration into an index. The tool's framework design allows researchers to continually update and refine the interpretations for many soils, climates, and land use practices. The tool was demonstrated using data from case studies in Georgia, Iowa, California, and the Pacific Northwest (WA, ID, OR). Using an expert system of decision rules as an indicator selection step successfully identified indicators for the minimum data set (MDS) in the case study data sets. In the indicator interpretation step, observed indicator data were transformed into unitless scores based on site‐specific algorithmic relationships to soil function. The scored data resulted in scientifically defensible and statistically different treatment means in the four case studies. The efficacy of the indicator interpretation step was evaluated with stepwise regressions using scored and observed indicators as independent variables and endpoint data as iterative dependent variables. Scored indicators usually had coefficients of determination (R2) that were similar or greater than those of the observed indicator values. In some cases, the R2 values for indicators and endpoint regressions were higher when examined for individual treatments rather than the entire data set. This study demonstrates significant progress toward development of a SQ assessment framework for adaptive soil resource management or monitoring that is transferable to a variety of climates, soil types, and soil management systems.

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Program, 1990;Mitchell et al., 1999). Mitchell et al. (1999) also reported a perceived decline in soil qualityThe high-value, large-scale crop production systems in the San among producers. As a result of these concerns, many Joaquin Valley (SJV) of California typically entail intensive tillage and large fertilizer and water inputs but few C additions to the soil.SJV producers have begun to question the long-term Such practices often contribute to a decline in soil quality. Our objec-sustainability of their intensively managed agricultural tive for this participatory study was to examine the effects of supplesystems. mental C management practices (SCMPs) on various soil quality To help farmers in the SJV evaluate the soil quality indicators. To increase farmer participation, we conducted the study effects of alternative soil management practices, the West on farms using a variety of SCMPs, including cover crops, compost and Side On-Farm Demonstration Project (WSD) was conmanure amendments, and several different crop rotations common ducted from 1995 to 1998. This participatory research to the region. The SCMPs significantly changed a number of soil and extension program originally included 11 large-scale properties, including soil organic matter (SOM); total Kjeldahl N; SJV row-crop producers, University of California Coopmicrobial biomass C and N; exchangeable K; Olsen P; and extractable erative Extension researchers, USDA Natural Resources Fe, Mn, and Zn. A comparison including previously established, adjacent organic, conventional, and transitional fields in addition to the Conservation Service (NRCS) conservationists, USDAtreatment fields at one farm revealed significant differences in 16 of ARS scientists, and private-sector consultants. soil quality indicators. A soil quality index computed for this farmDeveloping science-based guidelines to quantify imscored the established organic system significantly higher than the pacts of routinely used organic inputs in this region was conventional system. Our results suggest that significant changes in identified as an important priority among the project's several soil quality indicators occur with a variety of SCMPs. This is farmer participants (Mitchell and Goodell, 1996). A especially noteworthy considering the intensive tillage, irrigation, and brief, written survey of 15 participants, conducted durhot, semiarid environment of the SJV, California, where increases in ing a routine project meeting, invited input about their SOM and related soil properties are generally not expected in a 3-yr

Do extended crop rotations that include forages improve soil quality and are they profitable? Our objectives were to determine (i) how crop rotation affected soil quality indicators, (ii) if those indicator changes were reflected in soil quality index (SQI) ratings when scored and combined using the Soil Management Assessment Framework, and (iii) how SQI values compared with profitability. Soil samples were collected from three long-term studies in Iowa and one in Wisconsin. Bulk density (BD), soil pH, water-stable macroaggregation, total organic C, total N, microbial biomass C, extractable P and K, and penetration resistance were measured. The indicator data were scored using nonlinear curves reflecting performance of critical soil functions (e.g., nutrient cycling, water partitioning and storage, and plant root growth). Profit was calculated by subtracting costs of production from potential income based on actual crop yields and the 20-yr average nongovernment-supported commodity prices. Extended rotations had a positive effect on soil quality indicators. Total organic C was the most sensitive indicator, showing significant measured and scored differences at all locations, while BD showed significant differences at only one location (Kanawha). The lowest SQI values and 20-yr average profit were associated with continuous corn, while extended rotations that included at least 3 yr of forage crops had the highest SQI values. We suggest that future conservation policies and programs reward more diverse and extended crop rotations, as is being done through the Conservation Security Program.