Evaluating the effect of acidity on the optical characteristic of a soil sample

Imre T. TOLNER ¹, Kornél D. SZALAY ², László TOLNER ³, László FENYVESI ¹

¹ Hungarian Institute of Agricultural Engineering, Gödöllő Tessedik Sámuel street 4, Hungary tolner@fvmmi.hu

² Szent István University, Department of  Soil Science and Agrochemistry, Gödöllő, Hungary

³ Hungarian Institute of Agricultural Engineering, Gödöllő, Outer Agricultural Technical Department of Szent István University, Hungary Tessedik Sámuel u. 4, Magyarország

Summary: Diagnosing soil parameters is very important part of geology, agriculture and environment protection, too. Compared to the conventional methods, the hyperspectral remote sensing makes possible to evaluate the topsoil of large areas in fast and economic way. The spectroraimeter of  the Hungarian Institute of Agricultural Engineering is capable of gathering spectral information in the wavelength of 350 and 2500 nm. The spectral information referring to soils are usually studied in the upper range of this interval. Detection of soil acidity with remote sensing is not easy because practically we can only analyse the indirect effects of the pH change by measuring the characteristic of the reflected light from the surface of the soil.  As a result of the chemical reaction during the pH change new formation of molecules, molecule parts and ions are modifying the reflection parameters of the soil and this alteration can be measured. Through these changing factors we can conclude to the level of the soil acidity. In the following experiment we are examining the reflectance spectrum of one soil sample in laboratory. In order to make various pH levels the soil samples were treated differently with hydrochloric acid. As a result of the treatment the spectrums had modified. The spectral interval referring to the OH group showed significant dislocation.

Keywords: hyperspectral technology, soil acidity