LARS Tech Report Number
Salinization is a major factor in the deterioration of irrigated alluvial soils. To establish early detection measures to prevent soil salinity, panchromatic black and white aerial photographs, standard soil surveys and laboratory measures have been used to achieve such a goal since the 1930's.
Not until the 1960's was spectral reflectance, in multiband photography, used in an indirect detection of the effect of soil salinity upon crop leaves.
To study the specific spectral reflectance characteristics of different soil salinity levels, an area located to the west of Baghdad, Iraq was selected.
The applied research methodology was accomplished in three phases: (1) field data acquisition and analysis, (2) laboratory measurements of spectral reflectance characteristics of saline and gypsiferous soil s under different water content levels, before and after leaching, and (3) computer-digital-analysis of Landsat satellite MSS data and production of a final digitized map of the research area.
Laboratory measurements have indicated that saline soils have lower reflectance characteristics than do nonsaline and gypsiferous soils. The near and middle infrared bands were superior to the visible bands in detecting different soil salinity levels. Low reflectance was directly related to the type(s) of existing salts and their degree of solubility.
The digital analysis of Landsat multispectral scanner data demonstrated that spectral separation of different soil salinity levels and various land cover types is an efficient, reliable and dependable tool. The near infrared bands of Landsat were superior to the visible bands in characterizing different soil salinity levels.
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