Map of Potential Sequestration of Carbon by Arable Soils in Rostov Oblast Updated Using Rosstat Data

Since 2020, the project of the Global Soil Partnership of the Food and Agricultural Organization of the United Nations has been implemented to create a Global Map of the Carbon Sequestration Potential in the upper 0- to 30-cm layer of cropland (Global Soil Organic Carbon Sequestration Potential Map, GSOCseq). The first version of the national Russian map has been developed by local specialists using a standardized methodology. It is based on global databases, which do not account for specific local peculiarities. The aim of the study was to test new approaches in the pilot region with broad distribution of black soils for estimating the organic matter entering the system to quantitatively approximate it to real values. This paper describes the methodology for the transition of the input data block responsible for information about net primary products from global available resources to the local statistics of the Rosstat Municipal Database. The yield for the main crops, taking into account the cultivated area for each municipality, was recalculated into plant biomass using regression equations for determining the mass of plant residues according to the yield of the main product and then converted to an absolutely dry mass and multiplied by the coefficient of conversion of plant residues into carbon. After applying the new approach, differentiation was achieved at the municipal level and an increase in the results of the redistribution of climatic potential between territories was recorded. As part of the work, maps of the potential for sequestration of organic carbon by the upper 30-cm layer of arable soils in Rostov oblast have been constructed for the first time using Rosstat data. Previously, Rostov oblast was assessed as a carbon emitter according to previous methods; according to the new estimates, the entire Rostov oblast accumulates carbon; the average carbon sequestration is 0.032 t C ha^–1 per year even under the business-as-usual scenario. At the same time, according to the indicator of absolute sequestration rate, a significant increase in the sequestration rate has been recorded in the southern chernozem zone (Calcic Chernozems) and its slight decrease in the zone of ordinary chernozems (Haplic Chernozem). When implementing soil sustainable management scenarios, carbon can accumulate at an average rate of 0.063 to 0.161 t C ha^–1 per year and the total potential for carbon fixation can be estimated at 475–1244 Kt per year. The simulation results for Rostov oblast have shown that this approach can also be applied to federal subjects of the Russian Federation.