The publication of this Handbook was supported by the Russian Federation

Soil mapping by the use of  remote sensing
Soil salinity
Soil salinity assessments on the basis of  remote sensing data involve the use of  a series of  spectral 
indices such as colour saturation and brightness indices, soil salinity index and vegetation index (for 
more detail see [5], pp. 26-28). Such indices illustrate relationships between different aspects of  the 
study materials and their spectral characteristics.
Relationships between soil salinity and spectral indices differ for bare and vegetated soil surfaces. In 
cases of  bare surfaces, soil salinity correlates with indices calculated by the addition or multiplication 
of  brightness values of  visible and near-infrared light, but has no connection with vegetation index. 
An increase in soil salinity is reflected by an increase in brightness within the visible (especially, blue) 
and near-infrared spectra [12, 18]. However, the degree of  association between these parameters 
depends on the state of  the soil surface (e.g., whether it is moistened, cracked or trampled) as well 
as the mineralogical composition of  salt crusts [16, 17] (Fig. D.3).

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Annex D.Innovative methods of mapping and monitoring saline and alkaline soils 
Fig. D.3. The influence of the salt crust surface on the reflectance capacity (ground survey using a