Survey of methods for soil moisture determination

Increased interest in soil moisture information for applications in such disciplines as hydrology, meteorology, and agriculture has necessitated an overview of both existing and proposed methods for determination of soil moisture. This paper thus discusses methods of in situ soil moisture determination including gravimetric, nuclear, and electromagnetic techniques; soil physics models that track the behavior of water in the soil in response to meteorological inputs (precipitation) and demands (evapotranspiration); and remote sensing approaches that use the solar, thermal infrared, and microwave portions of the electromagnetic spectrum. The abilities of these approaches to satisfy various user needs for soil moisture information vary from application to application. Therefore we have proposed a conceptual scheme for merging these approaches into an integrated system. This system should provide soil moisture information having the potential for meeting the requirements of various applications.