Natalia Nikolaevna Kuzmenko

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.