The Content and Stratification of SOC and Its Humified Fractions Using Different Soil Tillage and Inter-Cropping

Five different tillage systems were researched in a Cambisol of a loam texture in the long-term experiment: conventional ploughing at 22–24 cm (CT), shallow ploughing at 16–18 cm (ShT), harrowing at 8–10 cm (MT1), harrowing at 14–16 cm (MT2), and no tilling (NT). The aim of this study was to determine how different tillage and inter-cropping influence the accumulation and distribution of SOC (soil organic carbon) and its compounds in different soil layers. SOC content changed depending on the soil tillage system and inter-crops used. Stratification ratios (SR) of SOC in the surface soil (0–10 cm) to that in the 10–20 cm (SR1) and 20–30 cm (SR2) were calculated. In our research, SR for SOC varied in the range from 0.97 to 1.35 for SR1 and from 1.02 to 1.99 for SR2. The main conclusion was that inter-crops increased the SOC accumulation in the 0–10 cm layer of all investigated treatments. It was concluded that different soil tillage systems and inter-crops influenced processes of soil carbon changes and affected OM humification in the soil. The formation of humified carbon compounds should be considered not only as a preservation and improvement of the soil productivity, but also as an environmental assessment of their impact on the soil sustainability and reduction in carbon dioxide emissions into the atmosphere. Our results suggest that sustainable tillage and inter-cropping management may contribute to climate mitigation regarding SOC accumulation in soil.