Spectral evaluation of three acidificated chernozem soil samples
Imre T TOLNER 1 – László TOLNER 2 – Kornél SZALAY 3 - László FENYVESI 4 - Miklós NEMÉNYI 1
1 University of West Hungary Faculty of Agricultural and Food Science, H-9200 Vár 2, Mosonmagyaróvár , Hungary, tolner.imre@mtk.nyme.hu
2 Szent István University, Department of Soil Science and Agrochemistry
3 Hungarian Institute of Agricultural Engineering, Outer Agricultural Technical Department of Szent István University
4 Hungarian Institute of Agricultural Engineering
Abstract: The improvement of soil fertility plays cardinal role in the precision agriculture. The fertility - and so the nutrition-management – are affected by soil acidity. Based on scientific sources the direct pH assessment of soil with remote sensing technologies is not possible. Accordingly in our study we use an indirect approach of pH determination.
The change of pH value also affects the hygroscopic attribute of soil. In the IR wavelength bands the water shows characteristic absorption features. Based on this changes of moisture content of soil can be detected by means of remote sensing applications.
In our institute - in the University of West Hungary (NYME) - we are working to develop an optical based method for measuring physical and chemical properties of soils, which is suitable for online soil pH measurement. The measurements were made with ASD FieldSpec 3 Max spectroradiometer in the Hungarian Institute of Agricultural Engineering, Gödöllő (VM MGI). The portable spectroradiometer is capable of measuring the spectral reflectance in the wavelength of 350-2500 nm. Measurements were carried out under precisely set laboratory conditions, nevertheless, our long-term aim is to apply and expand the obtained correlations under field conditions, too.
Three acidified chernozem soil samples have been evaluated. We modified the pH or rather the calcium-carbonate content of soil with five different hydrochloric acid treatments and studied the absorption peaks of reflectance spectra in those wavelengths which refer to water. As a result of treatments - in the water content-sensitive range of recorded spectra - the peaks referring to the -OH group were dislocated in various scale. This can be in relation with the change of the quantity of hygroscopic salt (calcium-chloride) which was formed as a result of the acid treatment.
Keywords: remote sensing, hiperspektral, soil, pH, humidity