Soils are spatially variable, reflecting local geology, topography, and climate within the global environment. As temporally integrated records, soils play an important role in global change research because they reflect present climate and land use, record past environmental changes, and influence future changes. Satellite-based remote sensing tools are valuable for their synoptic coverage that provides perspectives over broad regions and thus can be used to extend local knowledge of soils to regional and global scales. Multispectral remote sensing permits the estimation of soil properties associated with specific surficial deposits and landscapes. Direct linkages between remote sensing observations and soil properties involve the measurement of radiation emitted or scattered from the soil surface.
Indirect linkages involve correlation of vegetation cover and landform with soil properties.
Soil reflectance represents a cumulative effect of a heterogenous combination of mineral, organic, and fluid matter. 4.1 Spectral, spatial, and temporal forms of electromagnetic radiation emanating from soils. Consequently, soils nearly always have some effect on surface reflectance properties. A' and 'O' horizons are of primary concern. Soil mapping is mainly concerned with the permanent properties of the soil such as textural content, clay type, hydraulic properties, etc.