Soil water status and soil temperature are critical parameters for many applications, including continental-scale climate models, soil classification, and drought assessment.

National resource management issues for which long-term soil / climate information is needed include: To monitor drought development and trigger plans and policies for mitigation, Investigate climate change scenarios, To predict the long-term sustainability of cropping systems, and watershed health, To monitor and predict changes in crop, range, and woodland productivity in relation to soil moisture-temperature changes, To predict regional shifts in irrigation water requirements which may affect reservoir construction and ground-water levels, To predict shifts in wetlands, To develop new soil moisture accounting and risk assessments, To predict changes in runoff that affect flooding and flood control structures, To verify and ground-truth satellite and soil moisture model information, To predict and mitigate pest and disease outbreaks, For soil classification, For energy conservation, For Input to global circulation models

The Soil Moisture/Soil Temperature (SM/ST) Pilot Project was proposed in 1990 to test the feasibility of establishing a national soil-climate monitoring program that meets the growing demands of the global climate change community, modelers, resource managers, soil scientists, ecologists, and others. The project, a cooperative effort by the Resource Inventory Division and the Soil Survey Division of the Natural Resources Conservation Service, was to examine network communications, sensors, data collection electronics, station maintenance, data management, system interfaces, and management of a large national program.

Installation of 21 stations (in 19 states) began in 1991 and was completed the following year. Air temperature, relative humidity, precipitation, solar radiation, wind speed, soil temperature, and soil moisture were measured. Many changes were made to the original design, in response to lessons learned during the course of the project. Every aspect of the measurement system was evaluated critically and improved where practical.