Stocks of organic carbon in Estonian soils

The soil organic carbon (SOC) stocks (Mg ha(-1)) of automorphic mineral (9 soil groups), hydromorphic mineral (7), and lowland organic soils (4) are given for the soil cover or solum layer as a whole and also for its epipedon (topsoil) layer. The SOC stocks for forest, arable lands, and grasslands and for the entire Estonian soil cover were calculated on the basis of the mean SOC stock and distribution area of the respective soil type. In the Estonian soil cover (42 400 km(2)), a total of 593.8 +/- 36.9 Tg of SOC is retained, with 64.9% (385.3 +/- 27.5 Tg) in the epipedon layer (O, H, and A horizons) and 35.1% in the subsoil (B and E horizons). The pedo-ecological regularities of SOC retention in soils are analysed against the background of the Estonian soil ordination net.