## 3 Results
### Diversity of Microbial Bacterial and Fungal Communities  
The soil bacterial \(\alpha\)-diversity indices showed different patterns among treatments (Table 3). Overall, the Chao1 index decreased with soil depth, with the lowest values observed in CK and the highest values in RTS (0-20 cm soil layer) and PTS (20-40 cm soil layer) treatments. The Shannon indices under RTS (0-20 cm) and PTS (20-40 cm) treatments were higher compared to other treatments. However, no significant differences were found for Simpson indices across treatments.  
Figure 4: Effects of integrating straw return and tillage practices on soil SOC and its labile fractions. Bars with different lowercase letters denote statistically significant differences among treatments (\(p<0.05\)). The values represent means \(\pm\) se (\(n=3\)). Abbreviations: SOC (soil organic carbon), ROC (readily oxidizable organic carbon), DOC (dissolved organic carbon), MBC (microbial biomass carbon). Treatments as follows: CK (no straw + conventional tillage), NTS (straw mulch + no-tillage), RTS (straw incorporation + rotary tillage), PTS (straw incorporation + deep tillage).  
\begin{table}
\begin{tabular}{c c c c c c c c} \hline \hline \multirow{2}{*}{**Depth**} & \multirow{2}{*}{**Treatment**} & \multicolumn{4}{c}{**Bacterial**} & \multicolumn{3}{c}{**Fungal**} \\ \cline{3-8}  & & **[PERSON]** & **[PERSON]** & **[PERSON]** & **[PERSON]** & **[PERSON]** & **[PERSON]** \\ \hline \multirow{4}{*}{0–20 cm} & CK & 2991.33 \(\pm\) 53.76 c & 8.53 \(\pm\) 0.09 b & 0.998 \(\pm\) 0.002 a & 475.55 \(\pm\) 5.94 c & 3.29 \(\pm\) 0.15 a & 0.871 \(\pm\) 0.002 a \\  & NTS & 3341.00 \(\pm\) 39.0 b & 8.54 \(\pm\) 0.10 b & 0.997 \(\pm\) 0.001 a & 527.55 \(\pm\) 4.89 a & 3.20 \(\pm\) 0.17 a & 0.852 \(\pm\) 0.001 b \\  & RTS & 3743.33 \(\pm\) 46.25 a & 8.91 \(\pm\) 0.06 a & 0.996 \(\pm\) 0.002 a & 533.16 \(\pm\) 6.46 a & 3.11 \(\pm\) 0.10 a & 0.836 \(\pm\) 0.001 c \\  & PTS & 3201.67 \(\pm\) 60.89 b & 8.54 \(\pm\) 0.11 b & 0.996 \(\pm\) 0.001 a & 509.43 \(\pm\) 4.06 b & 3.27 \(\pm\) 0.19 a & 0.856 \(\pm\) 0.002 b \\ \hline \multirow{4}{*}{20–40 cm} & CK & 2581.33 \(\pm\) 44.83 c & 8.49 \(\pm\) 0.08 c & 0.999 \(\pm\) 0.001 a & 329.19 \(\pm\) 4.07 d & 3.22 \(\pm\) 0.14 a & 0.865 \(\pm\) 0.001 a \\  & NTS & 2938.00 \(\pm\) 52.29 c & 8.56 \(\pm\) 0.08 bc & 0.998 \(\pm\) 0.000 a & 366.10 \(\pm\) 6.15 c & 3.15 \(\pm\) 0.13 a & 0.853 \(\pm\) 0.001 b \\  & RTS & 3027.33 \(\pm\) 31.18 ab & 8.74 \(\pm\) 0.08 ab & 0.996 \(\pm\) 0.001 a & 388.45 \(\pm\) 5.82 b & 3.17 \(\pm\) 0.14 a & 0.854 \(\pm\) 0.002 b \\  & PTS & 3103.33 \(\pm\) 39.9 a & 8.88 \(\pm\) 0.05 a & 0.996 \(\pm\) 0.001 a & 448.22 \(\pm\) 7.14 a & 3.24 \(\pm\) 0.09 a & 0.856 \(\pm\) 0.002 b \\ \hline \hline \end{tabular}
\end{table}
Table 3: The diversities of microbial communities in the different integrated straw return and tillage practices.  
For fungal communities, the Chao1 index also decreased with increasing soil depth, though this did not affect the Shannon and Simpson indices. Compared to CK, all straw return treatments (NTS, RTS and PTS) increased the fungal Chao1 index. In the 0-20 cm layer, RTS treatment showed the highest fungal Chao1 index, while PTS treatment showed the highest fungal Chao1 index in the 20-40 cm layer. The Simpson index exhibited an opposite trend, with decreased values in all treatments. No statistically significant differences were observed for the Shannon index among treatments.