## 3 Results
### Mapping Total Solum SOC
The decrease of SOC with increasing mass balance index \(MBI(I)\) is in good agreement with net loss due to the lateral transport processes associated with positive \(MBI(I)\) values. \begin{table}
\begin{tabular}{l r r r r r r r r} \hline \hline  & \multicolumn{6}{c}{**Submodel for Terrestrial Soils (\(z_{\text{GW}}\) \(>\) 200 cm)**} \\ \(\boldsymbol{X_{j}}\) & \(\boldsymbol{b_{j}}\) & \(\boldsymbol{s_{bj}}\) & \(\boldsymbol{\hat{b}_{j}}\) & \(\boldsymbol{t_{j}}\) & \(\boldsymbol{p_{j}}\) & \(\boldsymbol{b_{j}-t_{95}s_{bj}}\) & \(\boldsymbol{b_{j}+t_{95}s_{bj}}\) & \(\boldsymbol{T_{j}}\) \\ \hline \(b_{0}\) & 120,171.553 & 23,687.729 & & 5.073 & 0.000 & 73,589.574 & 166,753.532 & \\ \(RSP(\boldsymbol{s})\) & 21,833.983 & 3433.882 & 0.316 & 6.358 & 0.000 & 15,081.245 & 28,586.720 & 0.489 \\ \(z_{\text{CaCO_{3}}}\) & 56.971 & 6.384 & 0.354 & 8.923 & 0.000 & 44.416 & 69.526 & 0.768 \\ \(\hat{S}\) & \(-83.837\) & 11.125 & \(-0.267\) & \(-7.536\) & 0.000 & \(-105.714\) & \(-61.960\) & 0.962 \\ \(\beta_{\text{C}}\) & 3523.879 & 351.225 & 0.452 & 10.033 & 0.000 & 2833.195 & 4214.564 & 0.596 \\ \(SPI\) & \(-724.272\) & 102.116 & \(-0.281\) & \(-7.093\) & 0.000 & \(-925.084\) & \(-523.460\) & 0.771 \\ \(P_{\text{win}}\) & 350.321 & 61.723 & 0.207 & 5.676 & 0.000 & 228.942 & 471.700 & 0.907 \\ \(s_{\text{DN}}(\boldsymbol{s})\) & \(-157.999\) & 32.076 & \(-0.247\) & \(-4.926\) & 0.000 & \(-221.076\) & \(-94.922\) & 0.482 \\ \(CF_{0...90}\) & \(-986.206\) & 229.538 & \(-0.157\) & \(-4.296\) & 0.000 & \(-1437.593\) & \(-534.819\) & 0.906 \\ \(\text{east}\times\beta\) & 1385.928 & 330.355 & 0.165 & 4.195 & 0.000 & 736.285 & 2035.571 & 0.781 \\ \(P_{\text{deciduous}}\) & \(-65.345\) & 21.793 & \(-0.126\) & \(-2.999\) & 0.003 & \(-108.200\) & \(-22.490\) & 0.685 \\ seriesI & 4550.659 & 2083.234 & 0.092 & 2.184 & 0.030 & 453.973 & 8647.344 & 0.674 \\ \hline \hline \multicolumn{1}{c}{**Submodel for Soil with a Near-Surface Groundwater Table (\(z_{\text{GW}}\leq 300\) cm)**} \\ \(\boldsymbol{X_{j}}\) & \(\boldsymbol{b_{j}}\) & \(\boldsymbol{s_{bj}}\) & \(\boldsymbol{\hat{b}_{j}}\) & \(\boldsymbol{t_{j}}\) & \(\boldsymbol{p_{j}}\) & \(\boldsymbol{b_{j}-t_{95}s_{bj}}\) & \(\boldsymbol{b_{j}+t_{95}s_{bj}}\) & \(\boldsymbol{T_{j}}\) \\ \hline \(b_{0}\) & 467,508.956 & 46,026.281 & & 10.157 & 0.000 & 376,026.739 & 558,991.173 & \\ \(\ln(z_{\text{GW}})\) & \(-74\),129.674 & 9063.024 & \(-0.613\) & \(-8.179\) & 0.000 & \(-92,143.415\) & \(-56,115.933\) & 0.957 \\ \(A_{\text{C}}\) & 0.718 & 0.158 & 0.342 & 4.541 & 0.000 & 0.404 & 1.033 & 0.950 \\ \(z_{\text{CaCO_{3}}}\) & 68.062 & 33.571 & 0.154 & 2.027 & 0.046 & 1.336 & 134.789 & 0.937 \\ \(MBI(I)\) & \(-356\),426.489 & 196,452.978 & \(-0.135\) & \(-1.814\) & 0.073 & \(-746\),898.055 & 34,045.078 & 0.975 \\ \hline \hline \end{tabular}
\end{table} 
Table 3: Selected covariates \(X_{j}\) for estimation of SOC stocks in the soil solum and the corresponding statistical parameters: regression coefficient \(b_{j}\) (\(10^{-4}\)), standard error of the regression coefficients \(s_{bj}\) (\(10^{-4}\)), standardised regression coefficients \(\hat{b}_{j}\), t-statistic \(t_{j}\), \(p\)-value \(p_{j}\), confidence interval bounds \(b_{j}-t_{95}s_{bj}\)and \(b_{j}+t_{95}s_{bj}\)(\(10^{-4}\)), and tolerance value \(T_{j}\). Especially for the various terrain attributes, the occurrence of multicollinearity, masking the individual variable importance, cannot be completely neglected. In particular, within the submodel for the terrestrial soils, some smaller tolerance values were observed. Despite these restrictions, the inspection of standardised regression coefficients \(\hat{b}_{j}\) clearly indicates a generally high importance of terrain parameters in the submodel for terrestrial soils. The highest absolute value of \(\hat{b}_{j}\) was found for the slope within the catchment \(\beta_{\text{C}}\). The soil property \(x_{\text{C}\text{C}\text{O}_{3}}\) is also of particular importance in this submodel.