Soil bacterial community characteristics and its effect on organic carbon under different fertilization treatments

Restoration type determines synchronic recovery of soil carbon, nitrogen, and phosphorus in mangrove wetlands

Restoration is essential for preserving the functions and economic benefits of mangrove ecosystems. Soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP) can help assess restoration effectiveness. However, it remains unclear whether active restoration (AR) with planting better recovers these nutrients than passive restoration (PR) without planting. We measured SOC, TN, and TP in four soil layers (0-10, 10-20, 20-30, and 30-40 cm) in experimental plots restored using AR and PR pond-to-mangrove methods over three years. The trials were compared to nearby natural mangrove forests in the Qinglan Harbor area of Hainan Island, China. We found that the SOC, TN, and TP contents in restored mangroves were significantly lower than those in natural mangroves, highlighting the long-term nature of ecosystem recovery. However, no significant differences were observed in SOC (10.40 ± 0.71 vs. 8.95 ± 0.54 g kg-1), TN (0.47 ± 0.04 vs. 0.44 ± 0.03 g kg-1), and TP (0.14 ± 0.01 vs. 0.09 ± 0.01 g kg-1) contents between AR and PR sites. This challenges the common assumption that AR is always superior to PR. The scaling slopes of the C:N:P stoichiometric relationships remained consistent (slope = 1) across the whole study area and at each site and soil depth, indicating tight coupling of these elements post-restoration. Soil salinity and bacterial community richness were identified as significant determinants of nutrient levels. Our findings suggest that both AR and PR are viable restoration options, depending on ecological needs, economic resources, and sustainability goals.

Sustainable Land Use Enhances Soil Microbial Respiration Responses to Experimental Heat Stress

Soil microbial communities provide numerous ecosystem functions, such as nutrient cycling, decomposition, and carbon storage. However, global change, including land-use and climate changes, affects soil microbial communities and activity. As extreme weather events (e.g., heatwaves) tend to increase in magnitude and frequency, we investigated the effects of heat stress on the activity (e.g., respiration) of soil microbial communities that had experienced four different long-term land-use intensity treatments (ranging from extensive grassland and intensive grassland to organic and conventional croplands) and two climate conditions (ambient vs. predicted future climate). We hypothesized that both intensive land use and future climate conditions would reduce soil microbial respiration (H1) and that experimental heat stress would increase microbial respiration (H2). However, this increase would be less pronounced in soils with a long-term history of high-intensity land use and future climate conditions (H3), and soils with a higher fungal-to-bacterial ratio would show a more moderate response to warming (H4). Our study showed that soil microbial respiration was reduced under high land-use intensity (i.e., -43% between extensive grassland and conventional cropland) and future climate conditions (-12% in comparison to the ambient climate). Moreover, heat stress increased overall microbial respiration (+17% per 1°C increase), while increasing land-use intensity reduced the strength of this response (-25% slope reduction). In addition, increasing soil microbial biomass and fungal-to-bacterial ratio under low-intensity land use (i.e., extensive grassland) enhanced the microbial respiration response to heat stress. These findings show that intensive land use and climate change may compromise the activity of soil microbial communities as well as their respiration under heatwaves. In particular, soil microbial communities under high-intensity land use and future climate are less able to respond to additional stress, such as heatwaves, potentially threatening the critical ecosystem functions driven by soil microbes and highlighting the benefits of more sustainable agricultural practices.

Fungal and bacterial community composition and assemblage in managed and unmanaged urban landscapes in Wisconsin

Microbial communities play crucial roles in ecosystem functioning, yet their diversity and assembly in urban turfgrass systems remain underexplored. In 2017, microbial communities within 48 samples from managed turfgrass (home lawns, golf course fairways, and putting greens) and an unmanaged grass mixture in Madison, WI, USA were analyzed across leaf, thatch, rhizoplane, and rhizosphere habitats Intensive management, particularly in nitrogen-rich, sand-based putting greens, reduced fungal richness and diversity, whereas bacterial diversity patterns varied. Beta diversity analyses revealed distinct clustering: fungal communities differed most in unmanaged systems, while bacterial communities clustered within managed systems. Functional profiling demonstrated that bacterial communities maintained metabolic stability despite taxonomic shifts, while fungal communities showed dynamic functional responses to management. Furthermore, management practices also impacted microbial community assembly. Bacterial communities were predominantly shaped by neutral, stochastic processes, while fungal communities were more sensitive to management, showing deterministic, niche-based assembly and compositional shifts. These findings underscore the contrasting impacts of management on microbial communities and highlight the importance of sustainable turfgrass practices that balance plant health with microbial ecosystem functions. By linking microbial assembly processes to functional outcomes, this study provides insights for optimizing urban landscapes to enhance soil health and ecosystem resilience.

Long-term garlic‒maize rotation maintains the stable garlic rhizosphere microecology

BACKGROUND

Crop rotation is a sophisticated agricultural practice that can modify the demographic structure and abundance of microorganisms in the soil, stimulate the growth and proliferation of beneficial microorganisms, and inhibit the development of harmful microorganisms. The stability of the rhizosphere microbiome is crucial for maintaining both soil ecosystem vitality and crop prosperity. However, the effects of extended garlic‒maize rotation on the physicochemical characteristics of garlic rhizosphere soil and the stability of its microbiome remain unclear. To investigate this phenomenon, soil samples from the garlic rhizosphere were collected across four different lengths of rotation in a garlic-maize rotation.

RESULTS

There were notable positive associations between the total nitrogen and total phosphorus contents in the soil and the duration of rotation. Prolonged rotation could increase the maintenance of microbiome α diversity. The number of years of rotation and the soil organic carbon (SOC) content emerged as principal determinants impacting the evolution of the bacterial community structure, with the SOC content playing a pivotal role in sculpting the species diversity within the garlic rhizosphere bacterial community. Additionally, SOC remains predominant in shaping the root-associated bacterial community's β-nearest taxon index. However, these factors do not have a notable effect on the fungal community inhabiting the garlic rhizosphere. In comparison with monoculture, rotation can amplify the interconnectivity and intricacy of microbial ecological networks. Long-term rotation can further maintain the stability of both microbial ecological networks and interactions between bacterial and fungal communities. It can enlist a plethora of beneficial Bacillus species microorganisms within the garlic rhizosphere to form a biological barricade that aids in safeguarding garlic against encroachment by the pathogenic fungus Fusarium oxysporum, consequently diminishing disease incidence. This study provides a theoretical foundation for the sustainable development of garlic through long-term crop rotation with maize.

CONCLUSIONS

Our research results indicate that long-term garlic‒maize rotation maintains stable garlic rhizosphere microecology. Our study provides compelling evidence for the role of long-term crop rotation in maintaining microbiota and community stability, emphasizing the importance of cultivating specific beneficial microorganisms to enhance rotation strategies for garlic farming, thereby promoting sustainability in agriculture.

Spent Mushroom Substrate Improves Microbial Quantities and Enzymatic Activity in Soils of Different Farming Systems

Organic fertilizers, such as spent mushroom substrate (SMS), improve soil fertility, but studies comparing their effects on different agricultural soils are limited. In this study, the effects of standard, SMS and composed fertilizers on soils from conventional-integrated, organic and biodynamic farming were investigated. Soil samples were analyzed for microorganisms and the activity of β-glucosidase (β-GLU), β-1,4-N-acetylglucosaminidase (NAG), urease (URE), arylamidase (ARN), phosphatase (PHOS), acid phosphatase (PAC), alkaline phosphatase (PAH) and arylsulphatase (ARS). Biodynamic soil showed the highest microbial counts and enzyme activities, followed by organic and conventional soils. SMS significantly increased the number of microorganisms and enzyme activities, especially in biodynamic and organic soils. Seasonal variations affected all microorganisms and most enzymes in all soils, except NAG in conventional and organic soils. Biodynamic soil showed stable activity of enzymes and microorganisms throughout the year, indicating greater stability. This study concludes that soil microorganisms and enzyme activities respond differently to fertilization depending on the soil type, with SMS demonstrating beneficial effects in all tested soils.

Impacts of farming activities on carbon deposition based on fine soil subtype classification

Introduction

Soil has the highest carbon sink storage in terrestrial ecosystems but human farming activities affect soil carbon deposition. In this study, land cultivated for 70 years was selected. The premise of the experiment was that the soil could be finely categorized by subtype classification. We consider that farming activities affect the soil bacterial community and soil organic carbon (SOC) deposition differently in the three subtypes of albic black soils.

Methods

Ninety soil samples were collected and the soil bacterial community structure was analysed by high-throughput sequencing. Relative changes in SOC were explored and SOC content was analysed in association with bacterial concentrations.

Results

The results showed that the effects of farming activities on SOC deposition and soil bacterial communities differed among the soil subtypes. Carbohydrate organic carbon (COC) concentrations were significantly higher in the gleying subtype than in the typical and meadow subtypes. RB41, Candidatus-Omnitrophus and Ahniella were positively correlated with total organic carbon (TOC) in gleying shallow albic black soil. Corn soybean rotation have a positive effect on the deposition of soil carbon sinks in terrestrial ecosystems.

Discussion

The results of the present study provide a reference for rational land use to maintain sustainable development and also for the carbon cycle of the earth.