## 2 Materials and Methods
On the basis of some empirical data from 240 runoff plots studied over the entire rainy season from diverse global ecoregions, Mueller-Nedebock and Chaplot [18] estimated that the total amount of SOC displaced by sheet erosion from its source would be \(1.32\pm 0.20\) Pg C, or about 11.4% of the annual anthropogenic emission of 11.5 Pg C in 2019 [21]. Integrating all C fluxes for the EU agricultural soils, [PERSON] et al. The author of [24] estimated a net C loss or gain of \(-2.28\) Tg CO\({}_{2}\) e/yr. and \(+0.79\) Tg CO\({}_{2}\) e/yr., and they argued that strong agricultural policies are needed to prevent or reduce soil erosion. Assessing and accounting for all the additional feedback and C fluxes due to displacement by erosion, [PERSON] et al. [15] estimated a net source of 0.92 to 10.0 Tg C/yr. from agricultural soils in the European Union to the atmosphere over the period of 2016-2100. The SOC being eroded is either deposited in the landscape, in the channel, or carried into the ocean (Figure 2). Some of the SOC being transported is emitted into the atmosphere as CO\({}_{2}\) or CH\({}_{4}\), depending on the degree of wetness or anaerbiosis. In China, [PERSON] et al. [17] observed that 42% of the eroded SOC was redeposited within the catchment. The mean residence time (MRT) of the deposited C depends on a range of site-specific factors, and the fraction composition (labile, intermediate, passive) of the eroded SOC. [PERSON] et al. [30] reported that cumulative emission of soil CO\({}_{2}\) decreased slightly at the erosion site but increased by 56% and 27% at the transport and depositional zones, respectively, in comparison to non-eroded sites. [PERSON] and colleagues concluded that overall, CO\({}_{2}\) emissions contributed 90.5% of the total erosion-induced C loss over the 4-month experiment. Whereas buried SOC at depositional sites may have a higher MRT even for the fast and intermediate turnover pools [31], \begin{table}
\begin{tabular}{c c c c c} \hline \hline
**Country/Region** & \
\begin{tabular}{c} **Study** \\ **Duration (yr)** \\ \end{tabular} & **SOC Erosion** &
\begin{tabular}{c} **Erosion** \\ **Types** \\ \end{tabular} & **References** \\ \hline Australia & 40 & 4 Tg SOC/yr. & all processes & [25] \\ Burkina Faso & — & 0.15–0.37 g C/m\({}^{2}\)-yr. & Water & [16] \\ China & 20 & 180 \(\pm\) 80 Mg C/yr. & Water & [26] \\ European Union & — & 0.05–0.45 Mg C/ha\(\cdot\)yr. & Water & [24] \\ Global & — & 1.32 \(\pm\) 2 G C/yr. & by sheet & Water & [18] \\ Global & — & erosion & Water & [10] \\ Global & — & 1.1 Pg C/yr. & Water & [17] \\ Global & 150 & 0.49 \(\pm\) 0.12 Pg C/yr. & Water & [27] \\ India & — & 115.4 Tg C/yr. & Water & [28] \\ Spain & — & 0.031 \(\pm\) 0.03 Mg C/ha\(\cdot\)yr. & Water & [14] \\ Turkey (Seyhan & — & 0.19 Mg C/ha\(\cdot\)yr. & Water & [29] \\ River Basin) & — & 0.19 Mg C/ha\(\cdot\)yr. & Water & [29] \\ \hline \hline \end{tabular}
\end{table} 
Table 1: Examples of regional, national, or global terrestrial soil organic carbon (SOC) erosion by water and other processes. Figure 3: Effects of accelerated soil erosion on the global carbon cycle and the increase in the daunting challenge of achieving land degradation neutrality. susceptibility to decomposition may be much higher for the labile fractions redistributed within the landscape. Examples of the magnitude of SOC erosion by water from different regions are shown in Table 1 and may range from 1.1 to1.3 Pg C per year. The preferential removal of SOC by water erosion is indicated by a high enrichment ratio of SOC (and clay) in sediments compared to that of the surface soil from which the sediments originated. Consequently, the enrichment ratio for SOC in alluvial sediments is \(>\)1 and may be as high as 12 (Table 2). Erosional processes lead to a preferential transport of SOC because it has a low bulk density and is concentrated in the surface soil layer. In cases where sediments are derived from subsoil (i.e., gully erosion), the enrichment ratio can be less than 1 [32].