Determination of Mineral Phases in Soils

In addition, we tried to detect P-phases in pure soil by Raman and synchrotron infrared microspectroscopic studies. Raman microspectroscopy measurements (with 413,532,633, and 785 nm lasers) of soils were impossible due to high fluorescence so the only information comes from synchrotron FT-IR microspectroscopy with its limited lateral resolution. 

The alluvial soil contains calcium carbonate (CaCOj), quartz, and montmo-rillonite ((Na,Ca)o33(Al,Mg)2Si 02o(OH)2). In the extracted spectra of CaCOj, 

The differences in fertilizer-soil reactions of calcium and magnesium (pyro-) phosphates, respectively, were successfully determined by Raman and synchrotron infrared microspectroscopic studies. All calcium orthophosphates convert to hydroxyapatite in soil over time. On the other hand, magnesium orthophosphates react only as far as trimagnesium phosphate because of then-inability to form an apatite structure. Thus, for the magnesium-based compound, phosphorus remains in a plant-available form. Also, the pyrophosphates of calcium and magnesium react very differently. Calcium pyrophosphate did not react in soil, whereas magnesium pyrophosphate quickly forms dimagnesium phosphate. Furthermore, mineral phases of soils were detectable by infrared microspectroscopy. 

Kazarian, S.G. and Chan, K.L. (2010) Appl. Spectrosc., 64, 135A-152A. 

and Kidder, L.H, (2005) in Process Analytical Technology (ed K. Bakeev), Blackwell Publishing Ltd, Oxford, pp. 187-225, 

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