Using Soil Survey and Ecological Sites to Assess Soil Health.

Soil survey organizes the landscape into common soils with similar characteristics and classifications.  Soil survey units can be used to predict soil behavior or capability and thus are useful for making management decisions and evaluating soil condition. Traditionally, in the U.S., soil survey mapping concepts have been developed with the dominant use of the landscape in mind.  Current enhancement of soil survey includes documenting dynamic soil properties and soil change due to ecosystem management.  Ecological sites are a concept used to describe ‘kinds of land’ that have common potential kinds and amounts of vegetation and characteristic response to disturbance.  The ecosystem dynamics are described in terms of state and transition models with states, communities, transitions and thresholds described.  In intensively managed (agronomic) systems, high inputs (e.g. energy, fertilizer, irrigation water) can confound and homogenize vegetation indicators.  In these situations, ecological site concepts can be differentiated based upon the ranges of soil function (indicated by dynamic soil properties) that occur as a result of the management (disturbance).  That framework can then serve as a basis for assessing soil health.  We have developed a tool to assist land managers in assessing soil health: Soil Health – Rapid Assessment Tool.  The tool integrates known information about ecological site and soil properties to guide users in selecting soil health indicators and using appropriate methods to measure those indicators.  Known information about the ecological potential and dynamic soil properties can be used to compare current condition to potential or capability.