SHAPEv1.0 Scoring curves and peer group benchmarks for dynamic soil health indicators

Abstract

The soil health concept has evolved over the past several decades, recognizing that the response of dynamic soil properties to management is dependent on site-specific factors. The Soil Health Assessment Protocol and Evaluation (SHAPE) tool provides scores and benchmark values by forming soil peer groups based on site-specific, climate-edaphic characteristics. Data for model development were compiled from the Cornell Soil Health Laboratory and the Kellogg Soil Survey Laboratory databases. The SHAPEv1.0 interpretation curves produce scores between 0% and 100% for measured laboratory values that reflect the quantile within a population conditional cumulative distribution function along with measures of uncertainty. The original SHAPE tool was developed for soil organic carbon and has been expanded to include two wet aggregate stability methods, permanganate oxidizable organic carbon, autoclaved citrate extractable protein, and 4-day microbial respiration. In addition, SHAPE provides site-specific benchmark values at user-defined percentiles within a given soil peer group. The difference between the actual measured value and the selected benchmark value represents the soil health opportunity gap. Case studies in Missouri and Texas show that the SHAPE scoring curves are sensitive to land-use and management practices across multiple soil types and provide a regionally relevant interpretation of key soil health indicators.