## 3 Results
\begin{table}
\begin{tabular}{c c c c c c c} \hline \hline
**Parameter** & **Treatment** & **2014** & **2015** & **2016** & **2017** & **2018** \\ \hline \multirow{4}{*}{GluN/GalN} & No-N & 2.21 \(\pm\) 0.01 a & 2.19 \(\pm\) 0.04 a & 2.21 \(\pm\) 0.04 a & 2.17 \(\pm\) 0.06 a & 2.16 \(\pm\) 0.05 a \\  & Low-N & 2.20 \(\pm\) 0.08 a & 2.20 \(\pm\) 0.07 a & 2.11 \(\pm\) 0.10 a & 2.06 \(\pm\) 0.08 a & 2.05 \(\pm\) 0.03 a \\  & Medium-N & 2.25 \(\pm\) 0.03 a & 2.19 \(\pm\) 0.05 a & 2.09 \(\pm\) 0.08 a & 1.99 \(\pm\) 0.05 b & 2.03 \(\pm\) 0.02 b \\  & High-N & 2.25 \(\pm\) 0.04 a & 2.20 \(\pm\) 0.06 a & 2.08 \(\pm\) 0.06 a & 1.99 \(\pm\) 0.04 b & 2.00 \(\pm\) 0.07 b \\ \hline \multirow{4}{*}{GluN/MurN} & No-N & 20.18 \(\pm\) 0.24 a & 19.74 \(\pm\) 0.38 a & 19.57 \(\pm\) 0.17 a & 19.68 \(\pm\) 1.22 a & 19.59 \(\pm\) 0.41 a \\  & Low-N & 20.07 \(\pm\) 0.44 a & 19.52 \(\pm\) 0.21 a & 19.55 \(\pm\) 0.93 a & 19.68 \(\pm\) 0.51 a & 19.52 \(\pm\) 0.54 a \\ \cline{1-1}  & Medium-N & 20.79 \(\pm\) 0.48 a & 19.34 \(\pm\) 0.50 a & 19.61 \(\pm\) 0.60 a & 19.03 \(\pm\) 0.63 b & 19.09 \(\pm\) 0.83 a \\ \cline{1-1}  & High-N & 20.66 \(\pm\) 0.39 a & 19.40 \(\pm\) 0.18 a & 19.24 \(\pm\) 0.42 a & 18.57 \(\pm\) 0.48 b & 18.38 \(\pm\) 0.37 b \\ \hline \multirow{4}{*}{Soil organic carbon (g kg\({}^{-1}\))} & No-N & 8.63 \(\pm\) 0.13 a & 8.69 \(\pm\) 0.11 a & 8.73 \(\pm\) 0.34 b & 8.74 \(\pm\) 0.13 b & 8.76 \(\pm\) 0.30 b \\  & Low-N & 8.69 \(\pm\) 0.37 a & 8.76 \(\pm\) 0.06 a & 8.85 \(\pm\) 0.18 ab & 8.93 \(\pm\) 0.19 ab & 9.05 \(\pm\) 0.23 ab \\ \cline{1-1}  & Medium-N & 8.69 \(\pm\) 0.01 a & 8.88 \(\pm\) 0.31 a & 8.97 \(\pm\) 0.25 ab & 9.18 \(\pm\) 0.07 ab & 9.39 \(\pm\) 0.21 a \\ \cline{1-1}  & High-N & 8.64 \(\pm\) 0.11 a & 8.95 \(\pm\) 0.08 a & 9.08 \(\pm\) 0.54 a & 9.24 \(\pm\) 0.50 a & 9.51 \(\pm\) 0.06 a \\ \hline \multirow{4}{*}{Soil pH} & No-N & 8.31 \(\pm\) 0.02a & 8.29 \(\pm\) 0.02 a & 8.26 \(\pm\) 0.01 b & 8.23 \(\pm\) 0.01 a & 8.20 \(\pm\) 0.01 a \\ \cline{1-1}  & Low-N & 8.31 \(\pm\) 0.02 a & 8.27 \(\pm\) 0.02 a & 8.23 \(\pm\) 0.01 ab & 8.21 \(\pm\) 0.01 a & 8.15 \(\pm\) 0.01 ab \\ \cline{1-1}  & Medium-N & 8.30 \(\pm\) 0.02 a & 8.24 \(\pm\) 0.02 a & 8.18 \(\pm\) 0.01 ab & 8.15 \(\pm\) 0.02 ab & 8.06 \(\pm\) 0.03 b \\ \cline{1-1}  & High-N & 8.30 \(\pm\) 0.01 a & 8.22 \(\pm\) 0.01 a & 8.15 \(\pm\) 0.01 a & 8.10 \(\pm\) 0.02 b & 8.01 \(\pm\) 0.02 c \\ \hline \hline \end{tabular} Mean values marked by different letters within the same column and parameter are significantly different from each other at 0.05 probability level.  
\end{table} 
Table 2: Effects of nitrogen enrichment on the glucosamine and galactosamine ratio (GluN/GalN), the glucosamine and muramic acid ratio (GluN/MurN), and soil organic carbon and pH content from 2014 to 2018. Figure 1: Effects of chronic nitrogen enrichment on glucosamine (**a**), galactosamine (**b**), muramic acid (**c**), and total amino sugar (**d**). Bars represent \(\pm\) standard error of means with four replications. to the control, the medium-N treatment increased bacterial residues in SOC by 4.73% in 2015, 11.49% in 2016, 16.02% in 2017, and 16.88% in 2018. The fungal residues in SOC were also significantly varied by the N enrichment from 2015 to 2018 (Figure 2b). Fungal residues in SOC ranged from 14.15 to 16.40 mg kg\({}^{-1}\) and it increased with an increase in N rate; but the fungal residues recorded by the high-N and medium-N treatments were statistically similar throughout the study period. The medium-N treatment stimulated fungal residues in SOC by 3.01%, 6.16%, 10.75%, and 11.31% in 2015, 2016, 2017, and 2018, respectively, compared to the control. Moreover, N enrichment significantly affected total microbial residues in SOC from 2015 to 2018 (Figure 2c). The total microbial residues in SOC ranged from 17.93 to 21.23 mg kg\({}^{-1}\) and it increased with increasing N rate.