International comparison of analytical methods of determining the soil organic matter content of Lithuanian eutric albeluvisols

Several soil organic matter (SOM) methodologies have been employed to analyze a Suite Of subsampled soils, and their results have been correlated. This will permit future comparison of the large archive of SOM databases, which widely exist in Lithuania and other Central and Eastern European countries, with those of other international Countries. Samples were collected (n = 92) from topsoil and subsoil horizons of Eutric Glassoboralfs (Eutric Albeluvisols) at five long-term monitoring sites (three sites with 8 years' duration and two sites with 20 years' duration) containing a total of 46 experimental field plots. Each soil sample was subsampled and SOM determined by several analytical approaches (namely, dry combustion, Walkley-Black, Tyurin photometric, Tyurin titrimetric, and loss-on-ignition methods). Correlation coefficients between multiple sets of results varied between r = 0.831 and r = 0.965 (n = 92, P < 0.001). Based on the strength and significance of these relationships, we propose that simple linear regression equations can be confidently employed to recalculate SOM data among various analytical methodologies and thus help resolve the issue of international data comparison.