## 3 Results  
### Soil Physicochemical Properties  
The classification of soil texture, based on various particle portions, is presented in Figure 2. The soil texture of the three grassland transects was between loamy and sandy, except for LP-MS (loamy) and MP-DS (sandy loam). The MP soil texture is loamy sandy loam and sandy loam, the TP is loamy sandy loam, and the LP is sandy loam and loam. LP soil had the lowest soil texture dispersion compared to the other transects' soil. The texture of the different grassland types changes from sand to clay as the precipitation gradient increases. MP: MS-DS (sand = 71.92-84.20%), LP: MS-DS (sand = 32.98-61.61%), and TP: MS-DS (sand = 51.00-70.81%). MP: MS-DS (clay = 3.56-2.03%), LP: MS-DS (clay = 5.23-1.98%), and TP: MS-DS (clay = 3.08-4.54%). The texture of the three grassland transects changed from sandy to clay loam with increasing temperature. Clay: LP (7.92 \(\pm\) 3.45%, CV% = 43.59) \(>\) MP (9.84 \(\pm\) 5.38%, CV% = 54.70) \(>\) TP (10.68 \(\pm\) 6.28%, CV% = 58.84). Sand: LP (63.67 \(\pm\) 16.47%, CV% = 25.88) \(>\) MP (75.80 \(\pm\) 12.15%, CV% = 16.03) \(>\) TP (50.48 \(\pm\) 17.40%, CV% = 34.48).  
The soil chemical composition was dominated by SiO\({}_{2}\), Al\({}_{2}\)O\({}_{3}\), and Fe\({}_{2}\)O\({}_{3}\) in the MP and TP and by SiO\({}_{2}\), CaO, and Al\({}_{2}\)O\({}_{3}\) in the LP (Table 2). The highest SiO\({}_{2}\) content (67.50 \(\pm\) 4.10%) was found in the MP among the three transects. The lowest content of SiO\({}_{2}\) and Al\({}_{2}\)O\({}_{3}\) in the three transects was LP soil (55.76 \(\pm\) 3.01, 12.97 \(\pm\) 1.42%). The highest content of CaO was LP soil (13.73 \(\pm\) 3.19%). The coefficient of variation of LP soil chemical composition was the lowest among the three transects, except Al\({}_{2}\)O\({}_{3}\) and Na\({}_{2}\)O. Sa and Saf are important indicators to evaluate soil chemical weathering [47]. The MP had the highest Sa and Saf (8.33 \(\pm\) 1.37, 6.77 \(\pm\) 1.35), and the coefficient of variation of Sa and Saf was also the highest (16.44, 20.00). Therefore, the weathering degree of the MP is the lowest among the three transects.  
\begin{table}
\begin{tabular}{c c c c c c c c c c c c c} \hline \hline
**Transect** & & \multicolumn{2}{c}{**SiO\({}_{2}\)**} & **Al\({}_{2}\)O\({}_{3}\)** & **Fe\({}_{2}\)O\({}_{3}\)** & **TiO\({}_{2}\)** & **MnO** & **CaO** & **MgO** & **K\({}_{2}\)O** & **Na\({}_{2}\)O** & **P\({}_{2}\)O\({}_{5}\)** & **Sa** & **Saf** \\ \hline MP & Mean & 67.50 \(\pm\) & 14.00 \(\pm\) & 5.30 \(\pm\) & 0.96 \(\pm\) & 0.31 \(\pm\) & 3.28 \(\pm\) & 1.56 \(\pm\) & 4.76 \(\pm\) & 2.03 \(\pm\) & 0.20 \(\pm\) & 8.33 \(\pm\) & 6.77 \(\pm\) \\  & 4.10 a & 1.53 a & 1.58 b & 0.24 c & 0.17 a & 1.57 c & 0.35 b & 0.36 a & 0.35 a & 0.05 a & 1.37 a & 1.35 a \\  & CV\% & 6.08 & 10.91 & 29.80 & 24.82 & 55.29 & 47.88 & 22.36 & 7.64 & 17.33 & 26.94 & 16.44 & 20.00 \\ TP & Mean & 59.21 \(\pm\) & 14.36 \(\pm\) & 8.13 \(\pm\) & 0.97 \(\pm\) & 0.16 \(\pm\) & 8.53 \(\pm\) & 2.34 \(\pm\) & 4.09 \(\pm\) & 1.50 \(\pm\) & 0.24 \(\pm\) & 7.10 \(\pm\) & 5.26 \(\pm\) \\  & 5.19 b & 1.86 a & 2.58 a & 0.20 b & 0.06 b & 7.31 b & 0.86 a & 0.82 b & 0.54 b & 0.09 & 1.04 b & 0.93 \\  & CV\% & 8.77 & 1.29 s & 31.73 & 2.11 \(\pm\) & 0.36 e & 88.572 & 37.00 & 20.02 & 35.80 & 39.59 & 14.69 & 17.67 \\ LP & Mean & 55.76 \(\pm\) & 12.97 \(\pm\) & 8.32 \(\pm\) & 1.17 \(\pm\) & 0.16 \(\pm\) & 13.73 \(\pm\) & 2.60 \(\pm\) & 3.34 \(\pm\) & 1.55 \(\pm\) & 0.18 \(\pm\) & 7.39 \(\pm\) & 5.26 \(\pm\) \\  & 3.01 b & 1.42 a & 1.23 a & 0.12 a & 0.03 b & 3.19 a & 0.29 a & 0.18 c & 0.30 b & 0.03 a & 0.94 b & 0.77 b \\  & CV\% & 5.41 & 10.92 & 14.73 & 10.04 & 18.83 & 23.25 & 11.21 & 5.29 & 19.12 & 16.94 & 12.72 & 14.66 \\ \hline \hline \end{tabular}
\end{table}
Table 2: Major element chemistry of soil samples (%).  
Figure 2: Soil textural classification of soil samples. TP: Tibetan Plateau; MP: Mongolian Plateau; LP: Loess Plateau; MS: Meadow steppe; TS: Typical steppe; DS: Desert steppe.