The collapse of Soviet Union in early 1990s led to abandonment of large area of arable land which is assumed to act as a carbon (C) sink. We studied the ability of two dynamic soil C models (Yasso07 and RothC) to predict changes in soil C content after cropland abandonment. The performance of the models was compared using the results of a long-term experiment in Pushchino, Moscow region (54A degrees 50'N, 37A degrees 35'E) in Russia. The experiment was divided in four combinations of fertilizer or mowing treatments on former cropland soil. The soil C content was determined in the year of establishment (1980) and thereafter in 1999 and 2004. The soil C stocks increased by about 1.5- to 1.8-fold during the study period. Both models predicted the overall change in soil C relatively well (modelling efficiency of Yasso07 and RothC were 0.60 and 0.73, respectively). According to the models, the soil gained on average 140-150 g C m(-2) year(-1) during the first 5 years after conversion of cropland to grassland. The C sequestration rate decreased to 40-50 g C m(-2) year(-1) after 20 years of land use change. The sequestration rates estimated in this study are comparable to the rates observed in other studies.
