欢迎点击上方名片关注！推送等相关事宜直接后台私信即可！土壤团聚体对于维持土壤功能至关重要。微生物接种剂正被越来越多地用于增强土壤生态系统过程；然而，其对土壤团聚体的影响及其调控因素仍然认识不足。本研究通过开展全球尺度的荟萃分析，量化了微生物接种剂对土壤团聚体的影响，并识别了这些效应的生物和非生物驱动因子。总体而言，微生物接种剂显著提高了平均重量直径（MWD）28.0%、几何平均直径（GMD）14.8%以及水稳性团聚体22.4%，表明团聚体稳定性得到明显改善。在不同类型接种剂中，丛枝菌根真菌（AMF）对MWD的促进作用最大，优于细菌和真菌接种剂。在温室实验中，微生物接种剂使MWD提高了30.08%。在非胁迫条件下，AMF和真菌接种剂效果更为显著，而在环境胁迫条件下，细菌接种剂表现更优。不同土壤和植被条件也影响接种效果：细质地土壤中的MWD响应高于其他土壤类型；草本植物条件下的响应高于其他植物类型。植物的存在显著增强了细菌和AMF接种剂的作用。此外，MWD的响应比（RR）与植物生物量、土壤有机碳（SOC）以及与球囊霉相关的土壤蛋白（glomalin-related soil proteins）的RR呈正相关。AMF通过促进根系生物量增加，从而提高SOC，进一步增强了MWD。这些结果表明，微生物接种剂在调控土壤团聚体形成方面具有重要作用，并强调在实际应用中需综合考虑微生物、植物与环境之间的相互作用，以实现对土壤结构的有效改善。
Fig. 1. Effects of microbial inoculants on soil aggregation. (a), the effects of microbial inoculants on soil aggregate size distribution, soil mean weight diameter (MWD), geometric mean diameter (GMD), and water stable aggregate (WSA). (b), the effects of different microbial inoculants on soil MWD. (c), the effects of overall microbial inoculants on soil MWD. (d), the effects of arbuscular mycorrhizal fungi (AMF) inoculants on soil MWD. Bars represent 95% confidence intervals (CIs). Mean values < 0 indicate a significant higher value in the control treatment (orange dots), whereas mean values > 0 indicate a significant higher value in the microbial inoculant treatment (blue dots). The significance of the model test for moderators (P < 0.05) indicates differences in response ratios (RR) within subgroups. The number of observations is indicated beside each attribute. For each pair of subgroups, the statistical significance is determined using Z tests. P values from the pairwise comparisons are corrected for multiple testing. Subgroups with the same letters are not significantly different, while those with different letters indicate significant differences (P < 0.05).
Fig. 2. The effects of microbial inoculants on MWD associated with a) initial soil pH, b) initial soil organic carbon (SOC), c) initial total nitrogen (TN) and d) initial available phosphorus (AP). Black lines represent the average responses with their 95% CIs shaded in grey. The one-sided F test is used to calculate P values.Fig. 3. Spearman’s correlations between the RR of MWD and the RRs of a) soil pH, b) TN, c) AP, d) glomalin-related soil protein (TGRSP), e) easily extractable glomalin-related soil protein (EEGRSP), f) SOC, g) root biomass, h) shoot biomass and i) plant biomass. Black lines represent the average responses, with their 95% CIs shaded in grey. n represents the number of observations. P values indicate significance (two-sided) and were adjusted using the Benjamini-Hochberg method with a sequentially modified Bonferroni correction.
Fig. 4. The relationships between colonization rate of AMF, RR of MWD, RR of root biomass and RR of SOC. (a), the effects of microbial inoculants on MWD associated with colonization rate of AMF, (b), the effects of microbial inoculants on SOC associated with colonization rate of AMF, (c), the effects of microbial inoculants on root biomass associated with colonization rate of AMF. (d), Spearman’s correlations between the RR of root biomass and the RR of SOC. (e), structural equation model depicting the influence of the colonization rate of AMF, RR of root biomass, and RR of SOC on RR of MWD (Fisher.C = 0.975, P = 0.614). In a, b, c, Black lines represent the average responses with their 95% CIs shaded in grey. The one-sided F test is used to calculate P values. In d, P values indicate significance (two-sided) and were adjusted using the Benjamini-Hochberg method with a sequentially modified Bonferroni correction. In e, the arrows represent the directional influence of one variable on another. The number beside the arrow is the corresponding standardized coefficient (r). All fitted coefficients are significant at α = 0.05. R2marginal and R2conditional represent the level of deviance of the variable explained by all paths from the fixed effects and both the fixed and random effects (‘StudyID’), respectively.
