Use of Low Temperature Ashing Coupled with DRIFT-FTIR Spectroscopy to Characterize Soil Organic Matter Resistance to Degradation.? 5th International Symposium of Interactions of Soil Minerals with Organic Components and Microorganisms

Low Temperature Ashing (LTA) by oxygen plasma coupled with DRIFT-FTIR spectroscopy has been used to study the dynamics, function and protection of soil organic matter (SOM) in undisturbed aggregates. As the LTA technique can remove SOM from the mineral matrix of soil aggregates with minimal disturbance and damage to the inorganic constituents, the gradual oxidation of SOM can be monitorized by both spectroscopic and chemical analysis. Undisturbed aggregates (0.5-1.0 mm size) from six different soils from the hilly area of Madrid (Spain), both under undisturbed forest and cultured/reforested plots of the same formerly forested areas, were subjected to LTA treatments of 1, 5 and 24 hours respectively, in order to obtain the dynamics of C removal. The samples before and after the removal of organic material at the different steps were analyzed by DRIFT-FTIR spectroscopy and the residual organic material in the aggregates was extracted by chemical methods. The findings showed that C removal dynamics by LTA can be related to the type of SOM and to its interactions with the different mineral constituents of the aggregates. The characterization of organic matter of undisturbed aggregates by DRIFT spectroscopy was compared with the one obtained by chemical methods of extraction