Soil improvement methods can result in changes in the microbial community in blueberry soil. Bacterial communities play an important role in soil fertilizer and plant nutrient acquisition. In this study, the response of microbial community composition, microbial function, and the nitrogen (N) cycle to different improvement methods was analyzed using high-throughput sequencing to investigate the best soil improvement method from a microbial perspective. The results showed that the highest microbial diversity was observed in the treatment involving peat combined with mushroom bran (T2), followed by the peat combined with acidified rice husk (T2) both in the rhizosphere and roots. The dominant phyla were Proteobacteria and Actinobacteria both in the blueberry rhizosphere soil and roots. Interestingly, Acidobacterium and Paludibaculum, belonging to the Acidobacteria phylum, exhibited the most significant influence and were most predominant in the T2 treatment rhizosphere soil. The T2 treatment promoted the growth of N fixation functional bacteria both in the rhizosphere soil and roots. At the module level, the T2 treatment enhanced N fixation and suppressed the assimilatory and dissimilatory nitrate reduction reactions, denitrification, and nitrification in the blueberry rhizosphere. Additionally, the T2 treatment increased the abundance of root endophytic microbes involved in N fixation. Overall, our findings suggest that the addition of peat combined with acidified rice husk is the optimal soil improvement method for blueberry cultivation.

Soil improvement methods can result in changes in the microbial community in blueberry soil. However, there have been few reports on the impacts of different soil improvement methods on the microbial function, particularly on endophytic microbe. In this study, we analyzed the response of microbial community composition, microbial function and nitrogen (N) cycle to different improvement methods using high throughput sequencing. We aimed to investigate the best soil improvement method from a microbial perspective. The results showed that the highest microbial diversity was observed in the T4 treatment (peat combined with mushroom bran), followed by the T2 treatment (peat combined with acidified rice husk) both in the rhizosphere and roots. The dominant phyla were Proteobacteria and Actinobacteria, which were most abundance in the T4 and T1 (peat combined with sulfur) treatments in the rhizosphere soil, respectively, but showed the opposite trend in the root endophytic bacterial community. Interestingly, Acidobacterium and Paludibaculum, belonging to the Acidobacteria phylum, were found to have the highest influence according to the correlation network analysis. And these bacteria were most abundant in the T2 treatment in the rhizosphere soil. The rhizosphere soil microbial communities were clustered into two categories: one for T1 and T2 treatments, and another for T3 (mushroom bran) and T4 treatments. Compared to the other treatments, the T1 treatment had the most significant impact on microbial functional pathways in the blueberry roots. T2 treatment promoted the growth of N fixation functional bacteria both in the rhizosphere soil and roots. At the module level, the T2 treatment increased the relative abundance of N fixation and decreased the relative abundance of assimilating nitrate reduction reaction (ANRA), dissimilating nitrate reduction reaction (DNRA), denitrification and completed nitrification in the blueberry rhizosphere soil. Additionally, the T2 treatment increased the abundance of root endophytic microbes involved in N fixation. Overall, our findings suggest that the addition of peat combined with acidified rice husk is the optimal soil improvement method for blueberry cultivation.

Soil organic carbon (SOC) is a core component of farmland fertility, and its content is significantly influenced by tillage practices. To clarify the effects of alternate tillage on soil organic carbon sequestration and soil aggregate stability, a tillage experiment was initiated in 2017. The study focused on the distribution of soil aggregates across different particle sizes and their organic carbon contents under four tillage treatments: (1) rotary tillage for two consecutive years after initial deep plowing (RT_DP); (2) no-tillage for two consecutive years after initial deep plowing (NT_DP); (3) continuous rotary tillage (RT); and (4) continuous no-tillage (NT). Compared with continuous rotary tillage (RT), RT_DP increased the crop yield by 14.78%, NT decreased the yield by 10.59%, and NT_DP increased the yield by 3.40%. In the topsoil, soil organic carbon (SOC) content increased by 21.57% under RT_DP, 24.47% under NT, and 21.57% under NT_DP. In the subsoil, SOC content increased by 36.91% under RT_DP, 24.80% under NT, and 42.52% under NT_DP. Compared with the RT treatment, practices such as RT_DP increased the SOC content and the proportion of macroaggregates. No significant differences were observed among all treatments in the topsoil. However, in the subsoil, RT_DP significantly increased the SOC content (by 36.91%), SOC content within >0.25 mm aggregates (by 35.75%), and the proportion of >0.25 mm aggregates (by 1.28%), relative to RT. Compared with NT, NT_DP also increased these three indices by 14.2%, 13.38%, and 0.32%, respectively. In the topsoil, the NT_DP treatment resulted in higher mean weight diameter (MWD) stability than the other treatments. In the subsoil, the NT treatment showed the highest MWD and geometric mean diameter (GMD) values, while both RT_DP and NT_DP had significantly higher MWD and GMD than RT. In the deeper soil layer, the NT treatment exhibited the highest aggregate stability. Further analysis indicated that the positive effects of alternate tillage (NT_DP and RT_DP) on aggregate distribution, aggregate stability, and subsoil SOC sequestration were mainly due to improvements in the soil’s nutrient availability, bulk density, porosity, and water content. The optimization of these soil properties further enhanced soil enzyme activity and ultimately promoted the stabilization and accumulation of SOC. In conclusion, incorporating deep plowing into rotational tillage can effectively promote SOC accumulation, especially in the subsoil of maize farmland, and enhance the physical protection of SOC. This study provides a practical tillage strategy for increasing the maize yield and enhancing soil organic carbon sequestration.