Abstract:

The topsoil spectral characteristics and spectral segments sensitivity to soil organic matter (SOM) were studied on the basis of laboratory analysis and spectral measurement of soil samples collected from 2 typical areas of desertification, and then models for estimating SOM of topsoil layer were established. The results showed that the soils of desertified lands had the unique wave-shaped spectral curves, with an obvious bow-shaped protuberance area in 500-900 nm wavelength range, which could be used to extract SOM information from soil spectrum. It was found by the correlation analysis that there were two spectral segments sensitive to SOM, centered at 600 and 830 nm wavelengths respectively. The result of model validation indicated that the models, taking the logarithm reflectance and reciprocal reflectance at 588 nm (lgR₅₈₈, 1/R₅₈₈) and the first derivative reflectance of reciprocal reflectance and logarithm reflectance at 835 nm (1/R₈₃₅)', (lgR₈₃₅)' as independent variable respectively, could be used to accurately estimate the SOM content in desertified lands.

Key words: desertified lands, soil organic matter, soil spectrum, estimate model