Applied Soil Ecology最新文献

The taxonomic and functional composition of the soil microbiome plays a crucial role in diverse ecosystem services including the carbon cycle and fertility, and is intricately linked to environmental conditions. Agricultural land abandonment followed by ecosystem changes and reforestation is widely spread in Eastern Europe and especially in Russia where up to 400,000 km² have been extracted from agricultural land-use and started to self-reforest. In boreal ecosystems, the reuse of abandoned lands for agriculture reduces the environmental risk connected with climate change. Therefore, there is a need to assess changes in soil parameters during long-term abandonment. This research aims to investigate the effect of natural pine reforestation on poor sandy ploughing lands on the taxonomic and functional composition of soil bacteria in Smolenskoe Poozerye National Park (western Russia). The soil microbial community of early stages (<30 years of pine reforestation) and older stages (>70 years of pine reforestation) differ significantly (p < 0.05): relative abundance of the dominant soil bacteria namely Acidobacteriota (13 % → 21 %), RCP2–54 (0.3 % → 6 %), Verrucomicrobiota (0.8 % → 0.9 %), Dependentiae (0.1 % → 0.7 %), WPS-2 (0.1 % → 1.2 %) increased, while the abundance of Actinobacteriota (24 % → 18 %), Chloroflexi (7 % → 0.7 %), Gemmatimonadota (2.8 % → 0.6 %), Myxococcota (3.2 % → 1.6 %), Bacteroidota (4.6 % → 1.5 %), Latescibacterota (0.1 % → 0 %), Nitrospirota (0.3 % → 0.01 %; p < 0.05) decreased. In the 0–30 cm topsoil humus horizon, the younger forest soil microbiome was more similar to soils of meadows and agrocoenoses than to the older forests due to previous plough. Differences between the upper and lower parts of the previously homogenized ploughed horizon become more evident during pine reforestation. In terms of predicted metabolic pathways, the younger soil microbiome produces siderophores and degrades organic substances more actively (p < 0.05). Older forest communities show higher activity of fermentation, photosynthesis, non-organic nutrient assimilation and respiration (p < 0.05). Our results also suggest that reforestation of poor sandy soils is not always beneficial for soil bacteria, since alpha-diversity decreases during succession and certain taxa are more abundant in soils of ploughing lands and native forests than at the transitional stages. The ploughing effect is preserved in soils studied for at least 30 years. The results obtained can be used in the environmental assessment to evaluate the degree and rate of restoration of soils in impacted areas.

Cover crops are used in cropping systems to enhance ecosystem services, such as soil resilience to erosion or microbial activity. Different cover crops are selected to steer specific processes, but whether cover crop mixtures have an added value over monocultures remains debated. Here, we investigated if cover crop mixtures accumulate soil microbiotas distinct from those of monocultures, potentially leading to more varied microbially-driven soil functions. We performed a field experiment at three locations in the Netherlands, each including nine cover crop monocultures, five- and eight-species mixtures, and a fallow control. After three months, we measured cover crop biomass and profiled soil bacterial, fungal, and arbuscular mycorrhizal fungal communities via amplicon sequencing. The different crop monocultures produced similar biomass across all three locations, and mixtures had average productivity compared to monocultures. The diversity and community structure of soil microbial communities was primarily determined by the geographical location, and then by cover crop treatment at each location. Although the cover crop species affected the soil microbiome differently, cover crop mixtures did neither increase microbial diversity nor the overall community differentiation compared to monocultures. Our results suggest that mixing cover crop species does not significantly influence microbially-driven soil functions, at least in short-term crop rotations.

The excessive use of copper-based agrochemicals poses a serious concern to viticulture worldwide. As a consequence, vineyard soil can become contaminated, leading to reduced vine growth and increased susceptibility to soilborne pathogens. Black foot, caused by various pathogenic species, including Dactylonectria macrodidyma, is a fungal disease that impacts the trunk and roots of vines. Enhancing plant biomass and productivity can involve various strategies, such as utilizing beneficial bacteria immobilized in biochar. This study aimed to investigate the impact of applying biochars derived from grape bagasse and enriched with Bacillus velezensis S26 endospores on alleviating copper stress, controlling black foot disease, and promoting the growth of the vine rootstock SO4 (Vitis berlandieri × V. riparia). Initially, we assessed various methods for immobilizing bacterial endospores into fresh bagasse biochar (FBB) and composted bagasse biochar (CBB). Subsequently, the cell viability of incorporated B. velezensis S26 endospores was evaluated over a 180-day storage at 4 and 25 °C. Finally, a pot experiment was conducted using micropropagated SO4 plants to investigate the growth-promotion capacity and biocontrol potential of both biochar and biochar enriched with B. velezensis S26 endospores. Our findings revealed that refrigerated storage ensured the highest cell viability in CBB, while no statistically significant difference was observed among the evaluated treatments for FBB. The application of B. velezensis S26 endospores, FBB, and CBB, either as a single inoculation or combined treatments, resulted in increased plant growth measurements. In addition, both FBB and CBB enriched with B. velezensis S26 endospores enhanced the growth and biomass of SO4 rootstocks cultivated in substrates with high copper concentrations or inoculated with D. macrodidyma TD1110. Furthermore, the frequency of pathogen re-isolation decreased by 29 % and 31.5 % using fresh and composted grape bagasse biochars enriched with bacterial endospores, respectively. Therefore, the utilization of fresh and composted bagasse biochars not only contributed to improving rootstock development measurements and suppressing the effects of D. macrodidyma TD1110 in SO4 vine rootstocks but also to waste valorization and a more sustainable agriculture.

In soil, multiple nutrients are cycled simultaneously (multinutrient cycling), rather than a single measurable process. While the impact of litter decomposition on individual soil nutrient cycling in alpine meadow ecosystems on the Tibetan Plateau is well-documented, its effects on soil multinutrient cycling remain unclear. We deployed a three-year litter application experiment in an alpine meadow on the Tibetan Plateau to examine the responses of soil microclimate, extracellular enzyme activities, and bacterial and fungal communities to litter applications, as well as the correlations between these vital factors with soil multinutrient cycling induced by litter application. We showed that litter application raised the soil multinutrient cycling index, temperature, and moisture content by an average of 190 %, 1.2 °C, and 12 %, respectively. Litter application increased the activities of soil extracellular enzyme β-1,4-glucosidase, β-1,4-xylosidase, β-D-cellobiosidase, L-leucine aminopeptidase, acid phosphatase, and phenol oxidase. Moreover, litter application increased the richness and diversity of both soil bacterial and fungal communities, and altered their community structure, but with larger effects on bacterial communities (R² = 0.43 for bacterial community and R² = 0.19 for fungal community). This indicates that bacterial communities are more responsive to litter application than fungal communities in alpine meadow soils on the Tibetan plateau. Partial least-square path modeling indicated that soil bacterial and fungal communities and extracellular enzyme activities were significantly positively correlated with soil multinutrient cycling after litter application. The relative abundances of bacterial phyla of Proteobacteria, Actinobacteria, and Verrucomicrobiota, and fungal phyla of Basidiomycota were positively related to most of the critical soil nutrients, indicating that those microbial taxa are the main drivers of soil multinutrient cycling. Overall, this study provides explicit evidence that litter application accelerates Tibetan meadow soil multinutrient cycling, which contributes to an enhanced understanding of the role of litter in sustaining the functions and services of alpine meadow ecosystems on the Tibetan Plateau.

Mangrove wetlands severely degraded over recent years, and mangrove restoration through planting has been practiced as an effective strategy to reconstruct mangrove wetlands. Nitrogen (N) availability has a decisive influence on mangrove growth, playing a crucial role in mangrove restoration. Diazotrophs can convert N₂ into plant-available ammonia (NH₄⁺) for plant absorption, and the diazotrophic species are vital to plant growth-promoting bacteria (PGPR) that are widely used as biofertilizers, which are important for plant growth and ecosystem restoration. Previous studies have identified some keystone diazotrophic species based on network analysis, which might potentially drive the community composition and function shift. However, the ecological functions of the keystone taxa and their effects on microbial interaction still need to be validated. In this study, the targeted keystone diazotrophic Novosphingobium sp. N034 identified by co-occurrence network analysis was isolated from mangrove sediments using a network-directed isolation method. Results showed that Novosphingobium sp. N034 inoculation significantly increased the plant height, sediment NH₄⁺-N content, and nitrogen fixation rate. Novosphingobium became dominant after 20 days of inoculation, and the relative abundance of some Fe(III)-reducing bacteria (FeRB) (e.g., Anaeromyxobacter, Geothrix, Deferrisoma, and Paludibaculum) increased. Moreover, the microbial inoculation also significantly increased the relative abundance of genes involved in dissimilatory nitrate reduction but decreased the relative abundance of anammox genes, potentially contributing to more efficient retention of nitrogen necessary for plants. Notably, a more complex and cooperative bacterial community network was observed by microbial inoculation. This study demonstrated that Novosphingobium sp. N034, identified as a keystone diazotrophic species, could optimize the sediment microbial community composition to promote mangrove growth. Our study also provided insight into the application of such keystone taxa for microbiome manipulation in mangrove restoration projects.

Long-term urban soil studies provide details of how urban soils develop over time. Urban soils are affected by regional and local pressures related to air pollution and introduced species such as earthworms and vegetation, which can affect change within relatively short periods of time. In Baltimore, forest soils of an urban–rural gradient were re-sampled, and it was found that, over two decades, calcium (Ca) concentration and pH had increased. These forest soils are habitats for populations of earthworms, which feed on the leaf litter and, consequently, locally alter the forest floor. Given the profound impact that earthworms have on soil properties, changes in soil chemistry were examined to determine any relation to shifts in earthworm community composition and abundance, with a special focus on the invasive jumping worms. To answer this question, earthworm assemblages in urban, suburban, and rural forest patches were sampled in 2002 and 2020. Species biomass and density were determined and then compared to samples collected at the same locations. In 2020, mean biomass and density varied between 91 and 33 g m⁻², and 388 and 12 ind m⁻², respectively. The results indicate statistically significant correlations between soil properties (pH, Ca, leaf litter depth, and bulk density) and earthworm abundance within a given year. However, changes in soil properties were independent of changes in earthworm species or abundance. The dynamics of earthworm assemblages appear to be different in urban forests than rural ones, with rural forests containing more jumping worms than urban ones, which uniquely affects the forest ecosystems.

Mining industrial sectors deteriorate local and regional environmental quality, contributing to global ecosystem contamination. The activities of microorganisms and enzymes involved in nitrogen cycling processes were investigated in coal dump soils that had undergone technogenic transformations and reclamation. Compared to the background uncontaminated soil, the heavy metal concentrations increased to high contamination levels (the contents of mobile forms of Zn, Ni, and Cu were 66.9; 35.6; 12.9 mg/kg, respectively), salinity increased to 0.1–2.41 %. The activities of nitrification and denitrification as well as the abundance of ammonifiers reduced due to high concentrations of mobile forms, the presence of coal particles, and the salinity of soil samples. The urease activity decreased due to reduced content of soluble organic matter in disturbed soils (2.3 times lower than the background soils). Mechanical reclamation leads to a 4-fold decrease in soil toxicity levels; however, it does not enhance nitrogen cycling activity. The activity of nitrification and urease decreased by >4 times as compared to the soil of the protected area. Microbial community composition of coal mine soils was similar to that of undisturbed soil. Nitrifiers in coal mine soil were represented by the genera Nitrososphaera, Candidatus Nitrosocosmicus, Nitrosospira, Nitrosomonas, Nitrosococcus, Nitrospira, Nitrobacter. The results indicated that the disruption of nitrification process led to low nitrate content in technogenically transformed coal dump soils.

The conversion from rice monoculture (RM) to rice-crayfish integrated system (RCIS) could change soil physicochemical properties and microorganisms related to greenhouse gas (GHG) emissions. Nevertheless, it is still unclear the responses of GHG emissions and global warming potential (GWP) from paddy fields to RCIS. Here, we conducted a field experiment to investigate the changes in the emissions of methane (CH₄) and nitrous oxide (N₂O), GWP, soil physicochemical properties and the associated microbial abundances (methanogen, methanotrophs, denitrifier and nitrifier) under RCIS in Gaoyou City, Jiangsu Province, China from 2022 to 2023. There were three treatments, including RM, rice monoculture with continuous deep flooding (RMF) and RCIS. Compared with RM, RCIS and RMF all significantly increased CH₄ emission and decreased N₂O emission. But the effectiveness of increasing CH₄ emission and decreasing N₂O emission was larger under RCIS than RMF. The increased CH₄ emission was due to the significantly higher mcrA gene abundance and ratio of mcrA/pmoA under RCIS. While the significantly higher nosZ gene abundance and ratio of nosZ/(amoA+nirK+nirS) under RCIS were responsible for its reduced N₂O emission. Furthermore, the increases in gene abundances of mcrA and nosZ under RCIS were closely correlated with the significantly lower redox potential and pH as well as the significantly higher contents of dissolved organic carbon, ammonium and nitrate in soil. Averaged across two years, GWP under RCIS and RMF were 4.6-fold and 3.4-fold that under RM, respectively. This revealed that continuous deep flooding had a greater effectiveness in increasing GWP than crayfish culture under RCIS. Notably, the contribution rates of CH₄ emission to the total GWP decreased in the order of RCIS (98.6%) > RMF (97.5%) > RM (86.2%). Besides, greenhouse gas intensity under RCIS was 5.1-fold that of RM due to its enhanced GWP and reduced rice grain yield. In summary, RCIS could enhance GWP from paddy fields through increasing CH₄ emission mainly caused by the continuous deep flooding.

Ensuring sustainable agriculture is crucial amidst global challenges, demanding effective methods to enhance soil health and nutrient cycling. Microbial inoculants, particularly arbuscular mycorrhizal (AM) fungi, offer promising solutions. However, concerns persist regarding the efficacy and quality control of commercial products. Past work assessing commercial inoculants have not controlled for fertilizers added to individual products when assessing product effects under typical use.

This study examines twenty-three mycorrhizal inoculants using conventions of organic production to shed light on differences between laboratory grown fungi, commercial products, and field soil. Employing a comprehensive approach, inoculants were assessed through spore enumeration, root infection potential, and crop growth response.

The results uncover significant shortcomings in many commercial products compared to laboratory grown fungi. Key findings include discrepancies of up to 100 % in reported propagule counts versus spore concentrations, insufficient root colonization by commercial inoculants, and contamination by fungal plant pathogens, particularly Olpidium, in products. Moreover, while laboratory grown fungi exhibited superior symbiotic relationships with host plants due to increased colonization abilities and crop benefit, commercial inoculants often failed to deliver significant growth benefits when fertilizers are controlled for.

These findings highlight the urgent need for improved standards and practices within the commercial inoculant industry.

Soil organic carbon (SOC) sequestration through innovations in agriculture, including integrating perennial grasses with annual crops, can mitigate climate change. However, integrating circular buffer strips (CBS) of perennial grasses with annual crops in water-limited semi-arid landscapes is a new concept, and how SOC and nitrogen (N) pools respond to CBS and what drives SOC sequestration in the surface and sub-surface depths with CBS integration in typical annual cropping is lacking. Our evaluation of the response of SOC and N fractions under buffer strip grass (BSG), adjacent buffer strip corn (BSC), and continuous conventional corn (CCC) without grass buffer after six years of grass establishment show contrasting trends. The SOC in 0–20 cm depth was 13.1 % greater under BSC than under CCC, while BSG had 49.7–68.2 and 17–29.9 % greater potentially mineralizable carbon (PMC) than CCC and BSC in 40–60 and 60–80 cm, respectively. Mineral-associated organic carbon (MAOC) in 60–80 cm depth was 29.9 % greater under BSG than CCC. Soils under BSC also accumulated 65.6 % more particulate organic carbon (POC) than under CCC in 0–20 cm. While POC contributed to SOC sequestration in surface soils, an increase in MAOC contributed to SOC accumulation in deeper profiles. Integrating buffer strips of perennial grasses enhances soil profile C sequestration in semi-arid agroecosystems through divergent mechanisms in surface and subsurface depths.