Soil Organic Matter Quality of Variously Managed Agricultural Soil in the Czech Republic Evaluated Using DRIFT Spectroscopy

This study focuses on the effect of agricultural soil management on soil organic matter (SOM) composition. The addition of manure and crop residues was tested under different pedoclimatic conditions. The quality of SOM was assessed using diffuse reflectance infrared spectroscopy. The following parameters were calculated from the spectra: sum of aliphatic bands (SAL), aromatic bands at wave numbers 1 620 and 1 520 cm-1 (AR1620 and AR1520), potential wettability (PWI), organic matter quality (OMQ), and decomposability (DI) indexes. The addition of manure or crop residues may not cause fundamental changes in the qualitative composition of SOM. Rather, pedoclimatic conditions determine which components are fixed in the soil on a long-term scale. A dominant effect of soil type was found in the distribution of all spectral parameters studied using main effect ANOVA. The main differences between the soil types concern the aromatic, oxygen and nitrogen groups contained in the SOM. Chernozems are soils with higher OMQ and DI, whereas Cambisols are soils with low OMQ and DI and the highest PWI. The stabilisation of SOM in soils can thus be based on the biochemical persistence of organic molecules, their specific affinity for minerals and the formation of aggregates that protect enclosed SOM.