Phytoremediation is an effective and ecological method used to control soil secondary salinization in greenhouses. However, the plant–soil interactions for phytoremediation have not been studied sufficiently. In this study, three crop species (Astragalus sinicus (CM), Spinacea oleracea (SP) and Lolium perenne (RY)) were compared in a greenhouse experiment. The results showed that all three crops increased the soil microbial biomass, the abundance of beneficial microorganisms, available phosphorus and soil pH, and reduced the soil salt content. The crop nutrient accumulation was positively correlated with the relative abundance of bacterial 16S rRNA sequences in the soil. CM and RY respectively increased the relative abundances of norank_f_Gemmatimonadaceae and norank_f_Anaerolineaceae within the soil bacterial community, while SP increased the relative abundances of Gibellulopsis within the fungal community. Correlation analysis revealed that pH and total dissolved salts were the vital factors affecting soil microbial communities in the secondary salinized soil. Our results suggest that phytoremediation could effectively alleviate secondary salinization by regulating the balance of soil microbial community composition and promoting crop nutrient accumulation.

Neighbouring plants can affect plant growth through altering root morphological and physiological traits, but how exactly root systems respond to neighbouring plants with varied density, determining nutrient uptake and shoot growth is poorly understood. In a pot-based experiment, rapeseed was grown alone (single rapeseed), or mixed with 3, 6, or 15 Chinese milk vetch plants. As controls, monocropped Chinese milk vetch was grown at the same planting density, 3, 6, or 15 plants per pot. Root interaction between rapeseed and Chinese milk vetch facilitated phosphorus (P) uptake in rapeseed grown with 3 plants of Chinese milk vetch. As the planting density of Chinese milk vetch in mixture increased, there was a decrease in citrate concentration and acid phosphatase activity but an increase in the total root length of Chinese milk vetch per pot, resulting in decreases in rapeseed root biomass, total root length and P uptake when rapeseed was grown with 6 or 15 Chinese milk vetch plants relative to rapeseed grown with 3 plants. These results demonstrate that the enhanced nutrient utilization induced by root interaction at low planting densities was eliminated by the increased planting density of the legume species in rapeseed/Chinese milk vetch mixed cropping system, suggesting that root/rhizosphere management through optimizing legume planting density is important for improving crop productivity and nutrient-use efficiency.

Soil microbes play a vital role in tidal flat ecosystems but are highly susceptible to disturbances from land reclamation. This study investigated the dynamics of bacterial communities and their environmental drivers across a 50-year reclamation chronosequence under three vegetation types (bare flats, reed beds, and rice fields). The results showed that, after 50 years of reclamation, total dissolved salts decreased significantly in vegetated zones, particularly in rice fields, where Cl⁻ dropped by 54.71% and nutrients (SOC, TN, TP) increased substantially. Key ions, including HCO₃⁻, Cl⁻, and K⁺, were the primary drivers of microbial community structure, exerting more influence than total salinity (TDS) or pH. Bacterial abundance and diversity increased over time, with rice fields showing the highest values after 50 years. Actinobacteriota and Proteobacteria were positively correlated with HCO₃⁻ and K⁺, while Cl⁻ negatively affected Acidobacteriota. Genus-level analyses revealed that specific taxa, such as Sphingomonas and Gaiella, exhibited ion responses diverging from broader phylum-level patterns, exemplifying niche-specific adaptations to salinity regimes. These findings underscore the pivotal role of vegetation type and individual salinity ions in driving microbial succession during tidal flat reclamation. A phased vegetation strategy, starting with reed colonization and followed by rice cultivation, can enhance soil quality and microbial diversity. This research provides important insights for optimizing vegetation management and ion monitoring in sustainable tidal flat reclamation.

In intensive vegetable production systems, long-term reliance on chemical fertilizers often leads to soil degradation and microbial imbalance, highlighting the need for sustainable biotillage strategies. In this study, a long-term field experiment examined how vegetable–earthworm co-cultivation (VE) combined with different fertilization regimes affects vegetable yield, soil physicochemical properties, and microbial communities. VE significantly improved vegetable yield, with full chemical fertilization (VE_IF100) and a 30% reduction in chemical fertilizer supplemented with organic fertilizer (VE_IF70) increasing yields by 30.86% and 26.02%, respectively, relative to full fertilization without earthworms (CK_IF100). VE also moderated soil pH toward neutrality. VE_IF100 decreased the soil C/N ratio, whereas VE_IF70 increased it and enhanced available hydrolyzable nitrogen, indicating a more balanced nutrient transformation. Microbial analysis revealed that VE_IF100 reduced bacterial abundance while strongly increasing fungal abundance, decreasing the bacteria-to-fungi ratio from 3.51 to 0.53. In contrast, VE_IF70 restored the bacteria-to-fungi ratio to 1.65 and increased fungal diversity, with the Shannon and Chao1 indices exceeding those in VE_IF100. Bacterial genera associated with nutrient cycling and plant growth promotion (e.g., Brevundimonas, Anaeromyxobacter) were enriched under VE_IF70, while fungal taxa with antagonistic and biocontrol potential (e.g., Chaetomium, Arthrobotrys) also increased. Redundancy analysis identified the soil C/N ratio (ranging from 5.94 to 8.60 across treatments) as a key driver of both bacterial and fungal community structures, whereas pH exerted a stronger influence on fungi. Random forest analysis indicated that the annual total vegetable yield was primarily driven by fertilization and available phosphorus in VE systems, whereas pH and bacterial abundance were the main drivers in CK systems. Overall, earthworm inoculation combined with partial organic fertilizer substitution improved soil conditions, reshaped microbial communities, and maintained high yield, demonstrating a practical strategy for sustainable vegetable production.