|Mitchell, Jeff - UNIV. OF CALIFORNIA DAVIS|
Submitted to: Agriculture, Ecosystems and Environment
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: October 20, 2000
Publication Date: N/A
Interpretive Summary: Consultants, farm advisors, resource conservationists, and other land managers may benefit from decision tools that help identify the most sustainable management practices. Indices of soil quality (SQIs) can provide this service. We tested various methods for choosing indicators and calculating indexes. The data we used was from alternative vegetable production systems being evaluated near Davis, CA. We compared the resulting indices with individual indicators, variables representative of management goals, and another statistical technique for decision making that uses all available data rather than a subset of indicators. Results suggest that a small number of carefully chosen soil quality indicators, when used in a simple, non-linearly scored index, can adequately provide producers with the information needed for selection of best management practices.
Technical Abstract: Consultants, resource conservationists, and land managers may benefit from decision tools that help identify sustainable management practices. Indices of soil quality (SQIs) can provide this service. We tested methods for choosing a minimum data set (MDS), transforming the indicators, and calculating indexes using data from alternative vegetable production systems near Davis, CA. The MDS components were chosen using expert opinion or principal components analysis (PCA). Multiple regressions of the MDS indicators against variables representing management goals showed no significant differences between the EO and PCA selection techniques in their abilities to explain variability within each sustainable management goal. In the comparison between linear and non-linear scoring techniques for MDS indicators, we determined the non-linear method to be more representative of system function than the linear method. Finally, we combined indicator scores using either an additive index, a weighted index, or a decision support system. For almost all indexing combinations, the organic system received significantly higher SQI values than the low input or conventional treatments. The efficacy of the indices was tested by comparison with another multivariate technique that uses all available data rather than a subset (MDS). That comparison showed results similar to all of the indexing combinations except the additive and weighted indices using the linearly scored, EO-selected MDS. Overall results suggest that a small number of carefully chosen soil quality indicators, when used in a simple, non-linearly scored index, can provide information needed for selection of best management practices.