## 3 Results and Discussion
### Effects of Hairy Vetch Cultivation and Amendment Types on Soil Microbial and Enzyme Activity  
Although chemical assessment has been widely used, it has a limitation that it only shows indirectly what the actual organism has affected [33]. So to compensate for that limitation, soil microbial activity and soil enzyme activity were analyzed for all groups and treatments based on when the hairy vetch were cultivated and harvested (Figure 2). All three types of amendments decreased SRA in NCNL and CNL groups, significantly. When liquid fertilizer was not applied, there was no significant difference in the changes in SRA due to hairy vetch cultivation. However, SRA increased nearly four times when liquid fertilizer and cultivation were incorporated (CL group). SRA also increased by LS and AMDS amendments, significantly. SRA is one of the oldest and most frequently used indexes for quantifying microbial activities by aerobic microorganisms [34]. Therefore, since aerobic microorganisms in LF flowed into and settled in soil, SRA appears to be very high in the CL group. The LF used in this study  
Figure 1: Distribution of root length, root weight and specific root length of hairy vetch after 4 weeks cultivation.  
was made through an aerobic aeration process of livestock manure and was sufficiently fermented by aerobic microorganisms. [PERSON] et al. (2018) examined total aerobic bacteria in domestic commercial LF (n = 33) and it ranged from 2.8 to 24.3 \(\times\) 104 CFU mL\({}^{-1}\). However, because LF contains not only aerobic microorganisms but also harmful pathogens, it should be used on the site after safety is secured.  
In the NCNL group, only AMDS increased DHA. When cultivation was performed, DHA was increased in all treatment and groups. In each group, the highest DHA was in the AMDS treatment, decreasing in the order of LS, RM and control. In addition, the synergistic effect of the increase in DHA was increased when liquid fertilizer and cultivation were simultaneously incorporated than when only cultivation was performed. The tendency of DHA results was similar in URA. When liquid  
Figure 2: Changes in soil microbial and enzyme activity according to various combinations of treatments (Con, control; LS, limestone; RM, red mud; AMDS, acid mine drainage sludge). Different letters indicate significant differences at the 5% level according to [PERSON]’s test between amendments.  
fertilizer was not treated, the effect of cultivation on URA was markedly different and the tendency to change according to the type of amendments was the same (AMDS = RM \(>\) LS \(>\) control). DHA and URA are enzymes that facilitate the oxidation/reduction reactions of substrates and catalyze the hydrolysis of urea [36; 37]. Since two enzyme activity act only on a specific substrate, unlike SRA, the results are more specific. In particular when comparing NCNL and CNL, the difference due to plant cultivation was clearly observed, and the difference due to the presence or absence of LF was also apparent when comparing CNL and CL. Synergistic effects of various complex treatments could not be confirmed through chemical assessment (Table 2), but could be confirmed through enzyme activity evaluation, biological assessment. [PERSON] et al. [38] showed that phytostabilization could improve soil biological properties (substrate induced respiration and nitrification activity). [PERSON] et al. [39] and [PERSON] et al. [40] evaluated the efficiency of phytostabilization using liquid peroxidation, reactive oxygen species-scavenging enzyme. These series of results reinforced the usefulness and clarity of biological assessment in a mixture of various types of treatments and will continue to be used in further study.