## 3 Results
### Influencing Factors on Soil Properties Variability
#### 3.3.2 Effects of Land Uses  
The physical and chemical properties of soil have close relationships with plant growth, soil microorganisms and soil enzyme activity, and some properties, such as pH and SOM, can affect the transfer, adsorption and availability of heavy metals. Thus, we first discuss the differences in heavy metals under different land use types. ANOVA was used to compare the differences among the seven land uses. Table 4 shows the comparison among the different land uses. It shows there are statistically significant differences in pH, SOM, TN, TP and TK content among land use types (\(p<0.05\)). For TN and SOM, the natural forest was higher, followed by the secondary forest. The secondary forest also had higher AP and AK content. A close observation reveals that artificial forest and farmland had lower soil nutrient levels.  
Table 5 indicates the heavy metals under different land uses. The \(F\) value by the ANOVA method showed that significant differences exist in most heavy metals, except for As, Cd and Ni. It is evident that the trends are similar among the different land uses.  
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Land Uses** & **pH** & **TN** & **SOM\%** & **AP(mg/kg)** & **AK(mg/kg)** & **TP\%** & **TK (\%)** \\ \hline Grassland & 6.50 (0.60) & 1.46 (0.52) & 2.38 (0.86) & 13.25 (7.90) & 181.68 (63.85) & 0.03 (0.01) & 2.10 (0.41) \\ Secondary forest & 6.12 (0.51) & 2.11 (0.43) & 3.81 (0.83) & 15.33 (15.47) & 184.46 (48.54) & 0.03 (0.01) & 1.48 (0.36) \\ Shrub land & 6.26 (0.49) & 1.59 (0.21) & 2.61 (0.42) & 13.93 (7.60) & 173.10 (80.89) & 0.03 (0.01) & 2.02 (0.48) \\ Dry land & 6.51 (0.31) & 1.63 (0.31) & 2.59 (0.57) & 10.55 (4.67) & 147.64 (67.48) & 0.02 (0.00) & 1.28 (0.31) \\ Artificial forest & 5.53 (0.55) & 1.62 (0.36) & 3.18 (0.90) & 7.19 (7.68) & 167.74 (79.90) & 0.03 (0.01) & 1.52 (0.49) \\ Paddy field & 6.09 (0.72) & 1.64 (0.71) & 2.52 (1.15) & 7.35 (1.67) & 116.63 (61.82) & 0.04 (0.01) & 1.54 (0.33) \\ Natural forest & 6.27 (0.59) & 2.14 (0.70) & 4.08 (1.57) & 10.38 (5.97) & 160.93 (47.09) & 0.04 (0.03) & 1.47 (0.40) \\ \(F\) value & 2.42 * & 1.68 ns & 2.46 * & 0.54 ns & 0.66 ns & 4.75 ** & 5.06 ** \\ \hline \hline \end{tabular} Numbers in the brackets denote the standard deviation. * Significant at the 5% level of probability. ** Significant at the 1% level of probability. ns indicates no significance.  
\end{table}
Table 4: Soil properties under different land uses.  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline
**Road** & **pH** & **TK** & **TP** & **AK** & **TN** & **SOM** & **AP** \\ \hline Level I & 6.2 (0.45) & 14,360.6 (3257.3) & 298.5 (115.9) & 211.2 (167.7) & 1.8 (0.4) & 3.2 (0.8) & 10.8 (9.7) \\ \cline{2-7} Level II & 5.9 (0.44) & 13,354.2 (2714.6) & 341.4 (93.4) & 113.1 (38.3) & 1.6 (0.4) & 2.9 (0.7) & 6.6 (3.6) \\ \cline{2-7} Level III & 6.1 (0.27) & 17,875.9 (3013.3) & 277.1 (78.8) & 126.1 (30.2) & 1.4 (0.3) & 2.2 (0.5) & 19.5 (12.9) \\ \cline{2-7} \(F\) value & 0.57 ns & 3.26 * & 0.43 ns & 1.33 ns & 2.52 * & 4.16 * & 2.26 ns \\ \hline \hline \end{tabular} Numbers in the brackets denote the standard deviation. * Significant at the 5% level of probability. ns indicates no significance.  
\end{table}
Table 2: Comparison of soil properties near different road levels.