Soil Organic Carbon Stock Estimation Based on Digital Map of Organic Carbon Stock in 30-cm Soil Layer of Russia

ABSTRACT Digital map of organic carbon stock in 30-cm soil layer of Russia was created within the frameworks of FAO UN project "Global Soil Organic Carbon Map" (GSOC17). Our objective was to develop and test algorithms for soil organic carbon stock (SOC) mapping on the basis of information accumulated in the Information System “Soil-Geographic Database of Russia”, i.e. vectorized soil maps, analytical characteristics of reference profiles and results of monitoring surveys. Calculations of the basic SOC map have performed in the form of synthesis of two types of source data: a map of the entire territory of Russia based on the Soil Map of RSFSR at the scale of 1:2.5 M (ed. V.M. Fridland, 1988) combined with irregular grid of about 2000 soil profiles and maps of several agricultural regions based on the large- and medium-scale soil maps and a dense grid of regular soil observations. Both maps were merged in one layer by superimposing more detailed maps over the map of entire territory. The SOC map for forest litter was calculated on the base of previously published map adapted to the GSOC17 requirements. The SOC map for muck and peaty horizons of semihydromorphic soils was calculated by using the averaged and expert estimations of stock values. The final version of the SOC map of Russia is a per pixel sum of all above maps. Our calculations indicate that the total carbon stock in 30-cm soil layer of Russia is about 150 Pg, and nearly half of this stock (45%) is concentrated in organogenic horizons