Minimum Property Dataset and Sampling Requirement Tool for Soil Change Studies in Soil Survey.

Dynamic soil properties (DSP) are those properties that change over human time scales. The new sampling guide “Soil and Resource Inventory Guide for Dynamic Soil Properties and Soil Change” includes a minimum DSP dataset and an interactive tool to determine sampling requirements. The minimum dataset is a common set of properties that will be measured on all DSP projects. In order to help guide soil property selection, a ranking tool was developed and completed by 40 experts in soil survey and pedology, soil biology, agronomy, forestry, rangeland, and hydrology. The ranking tool asked experts to rank properties according to 4 criteria important to soil change and soil survey. They ranked sensitivity to change the most important criteria for selecting a minimum DSP dataset. The highest ranked properties were organic carbon, pH and EC. The multi-scale sample requirement evaluation tool (MSSRET) is an Excel spreadsheet-based tool that can be used to determine the necessary sample requirements at plot and landscape scales for DSP monitoring and comparison studies. It is intended to help in project planning and sample sufficiency assessment. The Guide recommends sampling DSPs in a multi-scale fashion (multiple samples on multiple plots) by soil map unit component phases. Sample and plot requirements are calculated from the desired minimum detectable difference (MDD), the variance of the property at plot and project scales and the level of acceptable error rates. The guide represents a new phase in soil survey that will document DSPs and soil change due to management.