Organic carbon in long-fallow lands of Russia

The dynamics of organic carbon upon natural overgrowing of abandoned croplands transferred into the category of long-fallow lands is analyzed for the period from 1990 to 2002. The total area of long-fallow lands in Russia reaches 21.6 million ha. The dynamics of organic carbon in fallowed soils has been simulated using the ROTHC model. For this purpose, the territory of Russia was subdivided into 40 regions, for which the major soil characteristics, climatic data, and the input of organic matter into the soils have been averaged. The results of calculations show that the long-fallow lands of Russia have lost 9.9 million tons C org (36.4 million tons CO 2 ) in 13 years with the average loss rate of 0.46 t C/ha. It is expected that the accumulation of organic carbon will take place in the fallowed soils in the future.