Compared to total soil organic matter (SOM) the concentrations of water extractable organic matter (WEOM) are very small. Nevertheless, it is linked to many important soil functions. Numerous factors affect WEOM dynamics, most of them interacting in the same or in different directions. Therefore, there are still marked gaps in knowledge about WEOM. The majority of field studies have been done in forest ecosystems, and results on arable soils are scarce, contradictory and often do not fit to laboratory studies. Our purpose was to elucidate WEOM parameters in arable soils.