Modeling of Long-Term Carbon Sequestration by Arable Chernozem: Integrated Effects of Fertilization and Tillage

Using the RothC model, we predict the effects of tillage, fertilization system, and the return of crop residues on the carbon sequestration in the 0–20-cm arable layer in a long-term field experiment (commenced in 1976) with a leached chernozem. The dynamics of soil organic carbon (SOC) content is traced to the year of 2100 for three variants of organomineral fertilizers versus the control with moldboard tillage (MT) and conservation tillage (CT). As is shown, the SOC stock will amount to 79–83 and 81–85 Mg C/ha for MT and CT, respectively, after reaching an equilibrium level with an annual input of 2.9 Mg C/ha. The system with maximum fresh farmyard manure (FYM) doses and the return of crop residues reaches an equilibrium level by 8–16 years earlier as compared with the other systems for MT and by 16–24 years earlier for CT. This is associated with higher carbon stock in this system at the beginning of modeling and different qualitative SOC compositions. With an annual input of 4.6 Mg C/ha, a 4‰ and higher annual increase in SOC content is possible only in the first 20 years of increased carbon input. The effect of the system of fertilization at a high carbon input to agrochernozems lasts 40 years, and over 75 years at a medium carbon input.