## 3 Results
### Distribution and Basic Data of Root System  
We observed each _Amorpha fruticosa_ and discovered that while no first-order lateral roots were trapped in rock fissures, several secondary lateral roots were. Although the quantity of first-order lateral roots is far less than that of secondary lateral roots, their length and diameter are significantly greater. At various SAP dosages, the quantity and length of first-order lateral roots varied considerably (\(p\) < 0.05), and both number and length were negatively linked with SAP dosages. In comparison to the control group (CK), the number of first-order lateral roots decreased by 4.4%, 10%, 12.2%, 16.7%, and 20%, respectively. The length of the first-order lateral roots was successively reduced by 8.4%, 13.8%, 19.8%, 27.3%, and 34.5% from the control group (CK) (Figure 2a,b). The quantity of non-embedded secondary lateral roots was greater than the number of embedded secondary lateral roots, and both types of lateral roots declined in number and length with increasing SAP dosages. Overall, the number of two distinct types of lateral roots varied considerably across different water retention agent dosages. Compared with the control group (CK), the number of non-embedded secondary lateral roots decreased by 8.0%, 16.5%, 25.6%, 34.3%, and 40.0%; the length of non-embedded secondary lateral roots decreased by 7.6%, 15.0%, 22.0%, 29.5%, and 34.3%; the number of embedded secondary lateral roots reduced by 11.0%, 26.0%, 37.0%, 47.4%, and 57.6% (Figure 2a,b). \begin{table}
\begin{tabular}{c c c c c c c c c} \hline  & **CK** & **S30** & **S60** & **S90** & **S120** & **S150** & **n** & \(p\) \\ \hline Thickness (cm) & 11.2 \(\pm\) 0.71 & 11.1 \(\pm\) 0.9 & 11.3 \(\pm\) 0.5 & 11.5 \(\pm\) 0.8 & 11.7 \(\pm\) 0.6 & 11.6 \(\pm\) 0.8 & 5 & 0.232 \\ Bulk weight (g-cm\({}^{-3}\)) & 1.31 \(\pm\) 0.22 & 1.29 \(\pm\) 0.55 & 1.26 \(\pm\) 0.46 & 1.23 \(\pm\) 0.28 & 1.21 \(\pm\) 0.34 & 1.19 \(\pm\) 0.57 & 5 & 0.402 \\ Natural soil & & 13.48 \(\pm\) 0.76 & 16.53 \(\pm\) 1.16 & 18.74 \(\pm\) 1.11 & 20.57 \(\pm\) 1.53 & 22.74 \(\pm\) 1.78 & 24.18 \(\pm\) 1.33 & 5 & \(<\)0.01 \\ Soil water content after & & & & & & & & \\
24 h of watering (\%) & 25.46 \(\pm\) 0.71 & 27.41 \(\pm\) 1.22 & 30.33 \(\pm\) 1.76 & 32.67 \(\pm\) 1.55 & 35.18 \(\pm\) 1.82 & 38.33 \(\pm\) 1.76 & 5 & \(<\)0.01 \\ Total K (g/kg) & 6.62 \(\pm\) 0.31 & 6.39 \(\pm\) 0.34 & 5.87 \(\pm\) 0.49 & 5.31 \(\pm\) 0.56 & 5.12 \(\pm\) 0.69 & 4.86 \(\pm\) 0.44 & 5 & \(<\)0.01 \\ Total N (g/kg) & 2.93 \(\pm\) 0.22 & 2.71 \(\pm\) 0.26 & 2.48 \(\pm\) 0.17 & 2.21 \(\pm\) 0.27 & 2.06 \(\pm\) 0.19 & 1.88 \(\pm\) 0.15 & 5 & \(<\)0.01 \\ Total P (g/kg) & 2.33 \(\pm\) 0.18 & 2.17 \(\pm\) 0.12 & 2.05 \(\pm\) 0.16 & 1.88 \(\pm\) 0.09 & 1.71 \(\pm\) 0.11 & 1.88 \(\pm\) 0.15 & 5 & \(<\)0.01 \\ \hline \end{tabular}
\end{table} 
Table 2: Soil basic physicochemical index data. The diameters of first-order and secondary lateral roots were not significantly different at different water retention agent dosages (\(p\) = 0.918, 0.932). The diameter of both lateral roots was positively related to the amount of water retention agent (Figure 2c). In the downslope direction, the number of first-order lateral roots is larger than in the upslope (Figure 3a). The number of downslope non-embedded secondary lateral roots was greater than that of upslope roots (Figure 3b). The number of embedded secondary lateral roots in the upslope was slightly higher than those in the downslope (Figure 3c). The diameter of upslope non-embedded secondary lateral roots was higher than those of downslope roots (Figure 3e). When SAP was applied at a dosage of 120 g/m\({}^{2}\) (S120), the diameters of upslope first-order lateral roots and upslope non-embedded secondary lateral roots were substantially larger than those in the downslope. Figure 3: Fundamental data on upslope and downslope lateral roots.