Using Soil Survey to Assess and Predict Soil Condition and Change

Abstract

Soil survey organizes the landscape into units with common soil properties, characteristics, and classification. Soil survey units can be used to predict soil behavior and thus are useful for making management decisions and evaluating soil change. Traditionally, in the USA, 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. In intensively managed (agronomic) systems, inputs (e.g., energy, fertilizer, irrigation water) can confound and homogenize vegetation indicators. In these situations, ecological site concepts, as constructed through state and transition models, can be differentiated based upon levels of soil function (indicated by dynamic soil properties) that occur as a result of the management (disturbance). Groupings and interpreting soil properties using an ecological site framework can serve as a useful tool for soil resource management and assessment and bring whole ecosystem insight into management decisions. Such organizational frameworks should provide information about both reference conditions and alternative management systems of soil functions or dynamic soil properties within an ecological site. Reference conditions might reflect either native or naturalized vegetation or the highest possible function that an ecological site could support. A framework for assessing soil condition in two ecological sites/soil types is examined. The capacity of each ecological site is different as indicated by soil carbon content and aggregate stability. This information allows for documentation of soil change (from reference to alternative states or management systems); it could also be used as a reference for soil health assessments and could be used to enhance soil survey with land use and management-specific information.