Estimation of carbon stocks and stabilization rates of organic matter in soils of the "Ladoga" carbon polygon

Abstract

Soil organic matter (SOM) is a major component of the pedosphere. Due to the climate change, SOM may be subject to active biodegradation processes, land transformation and become a major source of greenhouse gases in the atmosphere. However, the overall effect of climate change on SOM content varies by region and soil type. Climate change can have catastrophic consequences for SOM, soils, and landscapes in general. Nowadays, different natural zones of our planet are subject to landscape degradation. Sustainable soil management aimed at increasing the content of SOM can increase the process of carbon sequestration, thereby contributing to the mitigation of climate change. Establishment of a network of carbon polygons for monitoring climatic processes as well as emission and deposition of carbon compounds in various ecosystems is one of the priority tasks in the field of climate and biosphere conservation as a whole. The most important area of work on the carbon polygon is the problem of assessing the reservoir and trends of stabilization of organic matter in different natural zones and ecosystems. By stabilization we mean the process by which SOM is formed resistant to biotic and abiotic influences and leads to an increase in the time of its turnover in the environment. The opposite of this process is destabilization, during which SOM components become available for use by microorganisms. This work presents the results of the study of the soil sections of the "Ladoga" carbon polygon. The Ladoga carbon polygon will be located in Voeykovo village, the south of Vsevolozhsk district of Leningrad region of Russia. The area is represented by fluvioglacial eskers relief form, in front of eskers uplands the Holocene lowland of Ladoga lake is located which is merged with current Ladoga waters edge. In the location the Folic Podzol (Arenic) and Fibric Histosol were considered. These soils are widely represented in the southern taiga subzone and can be used as benchmark monitoring soil sections. As a result of the analysis of chemical parameters it was revealed that Fibric Histosol and Folic Podzol (Arenic) are characterized by an acidic reaction of pH, pronounced podsolization and peat accumulation. In Fibric Histosol stores a significant amount of SOM up to 42.95 kgC/m2 . In the analyzing of the molecular composition of humic acids (HAs) extracted from the studied soils, it was found that HAs from Fibric Histosol were characterized by a relatively high content of aromatic structural fragments (51.28-56.83 %), while in Folic Podzol (Arenic) aliphatic structural fragments prevailed (56.23-63.08 %). The increase of aromatic structural fragments in the HAs composition indicates the stabilization of the SOM and an increase its turnover time in the environment. The creation of a monitoring network will make it possible to identify the main trends of SOM accumulation, to determine the conditions under which accumulation occurs, and to calcu-late its contribution to climate change on the planet. This work was supported by the Ministry of Science and Higher Education of the Russian Federation in accordance with agreement № 075-15-2022-322 date 22.04.2022 on providing a grant in the form of subsidies from the Federal budget of Russian Federation. The grant was provided for state support for the creation and development of a World-class Scientific Center "Agrotechnologies for the Future".