## 3 Results and Discussion
### Impact of Changed Soil Characteristics on Soil Microbial and Enzyme Activity  
As can be seen from the previous results, amendment treatment, liquid fertilizer treatment and hairy vetch cultivation changed soil characteristics. The relationships between soil biological characteristics and experimental results are summarized in Table 3. Both SRA and URA were mainly negatively correlated with soil pH and As availability and positively correlated with DOC and SRL. In the case of DHA, ammoniacal nitrogen had a negative correlation and SRL had a positive correlation. Particularly, SRL was found to have a significant positive effect on all soil biological characteristics. \begin{table}
\begin{tabular}{c c c c c c c c c} \hline \hline \multicolumn{2}{c}{**Treatment Group**} & \multicolumn{2}{c}{**pH**} & \multicolumn{2}{c}{**EC 1**} & \multicolumn{2}{c}{**DOC 2**} & \multicolumn{2}{c}{**NH4-N 3**} & \multicolumn{2}{c}{**NO3-N 3**} & \multicolumn{2}{c}{**Ex-As 4**} \\ \hline Non-cultivation 5  & Non-LF 6  & Con 7  & 8.32 \(\pm\) 0.01 & 0.22 \(\pm\) 0.00 & 234 \(\pm\) 0.64 & 6.8 \(\pm\) 0.32 & 7.0 \(\pm\) 0.16 & 8.2 \(\pm\) 0.11 \\  & & LS & 8.35 \(\pm\) 0.02 & 0.29 \(\pm\) 0.01 & 193 \(\pm\) 0.75 & 9.6 \(\pm\) 0.23 & 11.9 \(\pm\) 0.51 & 7.8 \(\pm\) 0.05 \\  & & RM & 9.02 \(\pm\) 0.04 & 0.31 \(\pm\) 0.01 & 416 \(\pm\) 5.52 & 11.9 \(\pm\) 0.25 & 12.8 \(\pm\) 0.48 & 7.7 \(\pm\) 0.16 \\  & AMDS & 8.25 \(\pm\) 0.07 & 0.36 \(\pm\) 0.01 & 138 \(\pm\) 1.91 & 12.0 \(\pm\) 0.16 & 14.1 \(\pm\) 0.15 & 1.0 \(\pm\) 0.09 \\ \hline Cultivation & Non-LF & Con & 8.24 \(\pm\) 0.03 & 0.16 \(\pm\) 0.00 & 187 \(\pm\) 3.78 & 10.3 \(\pm\) 0.47 & 7.8 \(\pm\) 0.35 & 8.2 \(\pm\) 0.28 \\  & & LS & 8.39 \(\pm\) 0.02 & 0.18 \(\pm\) 0.00 & 179 \(\pm\) 1.30 & 9.5 \(\pm\) 0.22 & 7.2 \(\pm\) 0.24 & 7.6 \(\pm\) 0.15 \\  & & RM & 8.91 \(\pm\) 0.03 & 0.29 \(\pm\) 0.00 & 337 \(\pm\) 4.91 & 9.7 \(\pm\) 0.43 & 11.7 \(\pm\) 0.52 &It is known that the sensitivity of SRA varies depending on the soil pH. In low soil pH, SRA was not sensitive to pH change [41]. In addition, the effect of pH on SRA is not significant with the pH range of 6 to 8 [42]. However, in alkali conditions, the increase in soil pH has a negative effect on SRA via biochemical reactions [42; 43; 44]. The soil used in this study had a pH of 8 or higher in all treated soils. Therefore, the SRA tends to decrease with increasing pH according to the treatment group, and it is shown that the pH constant is negative in the regression equation. It is known that the tendency of enzyme activity to be inhibited by high pH in alkaline soils is similar in SRA as well as in URA [45]. Not only pH but also bioavailable As has a negative effect on SRA and URA. The presence of bioavailable As in soil decreased the production of soil enzymes, resulting in a decrease in soil enzyme activity [46]. Also, the greater bioavailable As in the soil, the greater the exposure and absorption into microorganisms. Thus, the high concentration of As generated a large amount of reactive oxygen species (ROS), and when the ROS exceed the microbial unique antioxidant mechanism (including enzymatic and non-enzymatic), it causes oxidative stress resulting in the inhibition of soil organisms [47; 48]. Therefore, both SRA and URA were significantly and negatively correlated with bioavailable As. On the other hand, both DOC and SRL have a positive effect on SRA and URA and it seems to be caused by LF treatment and the rhizosphere effect. The LF used in the experiment contained a high concentration of organic matter, and the root also produced root exudates and were released into the soil [49; 50]. It could be summarized that LF treatment has a positive effect on SRL and DOC, and strengthened SRL increased DOC again. For DHA, ammonium ion content was found to have a negative correlation (Table 3). Nitrogen is one of the essential macro elements of plant growth, and plant roots could absorb ammonium and nitrate ions in particular, so their concentration in soil would have a positive effect on plant growth [51].