Pavel Vladimirovich Krasilnikov

Abstract The RothC-26.3 model was used to reproduce the 62-year dynamics of soil organic carbon (SOC) in Retisols within a long-term field experiment conducted by the Federal State Budget Research Institution «Federal Research Center for Bast Fiber Crops». Simulation modeling was employed to assess the potential for increasing SOC stocks by 2090 through modifications in agrotechnological practices under two climate scenarios and two adaptive economic scenarios. The feasibility of utilizing alternative fertilizer sources and minimal tillage as supplementary approaches for SOC accumulation was examined. The results indicate that under existing management practices and future climate conditions, SOC stocks in the topsoil (0–20 cm) of the studied soils could increase by up to 34% of the initial content by 2090. Furthermore, the implementation of carbon-saving technologies—including adjustments to crop rotation structure, as well as the rates and sources of organic fertilizer application—could enhance SOC accumulation, leading to a potential increase of up to 82% by 2090. Under different climate scenarios, the maximum sequestration rate was projected to reach up to 11‰ per year. Among the alternative organic fertilizers evaluated, the application of composts and peat mixtures yielded the most favorable outcomes, facilitating an additional SOC accumulation of up to 10.6 tha–1 compared to the use of cattle manure. In contrast, the use of green-manure fallows and minimal tillage cannot be considered an optimal strategy for SOC sequestration, as these practices resulted in lower accumulation relative to cattle manure application. It was demonstrated that the studied soils possess considerable potential for organic carbon accumulation while remaining under agricultural cultivation.

The most important factor affecting the soil organic carbon (SOC) stocks is the degree and nature of soil moisture content. This factor is especially important when assessing SOC in forest soils. In this paper, the results of a comparative statistical analysis of the variability of SOC in automorphic, semihydromorphic and hydromorphic forest soils in Karelia are discussed. To estimate SOC stocks and calculate quantitative indicators of their variability, soil survey data were used over an area of 1 km2. The information was collected into a single array, which includes the characteristics of 95 soil profiles of forest ecosystems. Of these, 61 profiles characterize automorphic soils, 12 profiles characterize semihydromorphic soils and 22 profiles characterize hydromorphic soils. The results of the studies showed that the mineral horizons of forest soils are largely heterogeneous in terms of SOC content, while organogenic horizons are more heterogeneous in terms of thickness and density. The results of statistical analysis showed that the average SOC stocs in the 0–30 and 0–50 cm soil layers increase depending on the degree of hydromorphism. The results of statistical analysis showed that SOC stocks in semihydromorphic soils are characterized by higher variability, as evidenced by a larger range of changes, higher standard deviations and coefficient of variation. In automorphic soils, the 0–5 cm layer, corresponding to the litter, accounts for up to 30% of the total organic carbon reserves in the 0–50 cm layer. With increasing hydromorphism, this share decreases to 17% in semihydromorphic soils and to 6% in hydromorphic soils. The share of SOC reserves in the 30–50 cm layer in total reserves increases from 23% in automorphic soils to 43% in hydromorphic soils.