Satellite assessment of dehumification of arable soils in Saratov region

Possibilities of using satellite data for the evaluation of soil degradation processes on arable lands in Saratov region were analyzed. A regression model describing the relationships between the humus content in the upper layer of arable soils and their spectral reflectance was developed and applied to assess dehumification in the studied region on the basis of Landsat TM5 images. It was found that the humus content on 36.3% of test fields decreased by 1–2% in the period from 1988 to 2011. On the slopes with slightly eroded soils, the humus content decreased by 1.4–1.6% (in some cases, up to 2.5%); on the slopes with moderately eroded soils, by 1.8–2.0% (up to 2.8%). During the considered period, the area of slightly eroded soils increased by almost two times, and the area of moderately eroded soils increased by nearly three times. The most pronounced reduction in the humus content took place in the soils developed from sands, loamy sands, and sandy loams. An increase in the humus content was identified on the lower parts of the slopes (13.44% of test area), where the accumulation of the high-humus soil material eroded from the upper parts of the slopes could take place. © 2015, Pleiades Publishing, Ltd