Development of Soil Health Metrics for Improving Soil Productivity and Food Security Challenges.

The Comprehensive Assessment of Soil Health (CASH) is an approach that measures 15 physical, biological, and chemical soil indicators, which are interpreted through scoring functions. They were selected from 42 potential soil health indicators that were evaluated for sensitivity to changes in soil management practices; ability to represent agronomically and environmentally important soil processes; consistency and reproducibility; ease and cost of sampling; cost of analysis; and ease of interpretation for users. The CASH test was rolled out in 2006 and we recently analyzed the results from 5767 samples from the Mid-Atlantic, Midwest, and Northeast regions of the USA. Descriptive statistics and ANOVAs of sub-datasets by region and soil textural group for SH indicators, in addition to correlation coefficients, principal component (PC) analysis, and best subsets regression (BSR) were performed. From these analyses, new CASH scoring functions were developed. Differences existed among regions, especially for WAS, OM, Protein, and Respiration (Resp), where the Midwest had relatively lower mean values compared to the Mid-Atlantic and Northeast. Biological properties and WAS showed moderately strong correlations (r = 0.58–0.78) and the highest loadings for the first two PCs. BSR results using the overall soil quality index as the response variable indicated that AC accounts for 45% of the variation, with additional predictability from Penetration Resistance, Resp, and WAS (68%). These four indicators are suggested for simplified SH tests. We conclude that the CASH approach can be successfully applied to evaluate the health status of soils with differing pedogenetic histories.