European Journal of Soil Biology最新文献

Earthworms are classified as ecosystem engineers, given their ability to modify resources and habitats for other organisms. However, they are also strongly influenced by the land uses changes. Our study investigated the impact of different agricultural systems (rotational grazing versus continuous grazing ; cropping systems in pasture phase versus crop phase) on earthworm communities (diversity, biomass, density and body mass) in Uruguay, a context that is still poorly documented. We found a total of nine earthworm species. Rotational and continuous grazing systems exhibited similar mean richness (2.67–2.33, respectively), while in the crop phase, the mean richness was 2 points higher than that of the pasture phase (5.67 and 3.67, respectively). The results of the principal component analysis confirmed an overlap between the two grazing systems, rotational and continuous, indicating similarities in earthworm species composition in these systems. On the other hand, the pasture phase showed partial overlap with the grazing systems but the crop phase did not overlap with any of other three land uses. No significant difference was found in biomass in rotational grazing versus continuous grazing and in pasture phase versus crop phase. Earthworm density was significantly higher in rotational grazing compared to continuous grazing and in the crop phase compared to pasture phase. Body mass differences were observed in different land uses or developmental stages, observing in average smaller earthworms in rotational grazing compared to continuous grazing. Co-inertia analysis revealed associations between soil variables and earthworm biomass and body mass. Soil variables, including clay and calcium, strongly correlated with earthworm biomass. This study highlights the complexity of earthworm responses to land use, challenging logical interpretations. Further research is needed to elucidate the nuanced interactions between earthworm communities and environmental variables, providing valuable insights for sustainable land management practices, since both soil and plant health is known to be enhanced by the presence of earthworms.

Research has explored the impact of organic fertilisation on improving agroecosystem productivity and resilience, highlighting the significant contributions of protists in addition to bacteria and fungi. However, the interactions among bacteria, fungi and protists in organically fertilised soils remain largely unknown. In this study, soil samples were collected from four long-term fertilisation treatments: no fertilisation (Control), inorganic fertilisation (NPK), organic fertilisation (OM), and combined inorganic and organic fertilisation (NPKOM). The abundance and composition of bacteria, fungi, and protist communities, as well as co-occurrence networks, were analysed under different fertilisation treatments. Our results showed that the total abundance of bacteria, fungi, and protists increased by a minimum of 2.95, 3.47, and 0.66 times, respectively, after organic fertiliser application. Moreover, the application of organic fertilisers significantly altered the structures of soil microbial communities by enriching bacterial Proteobacteria and Actinobacteria, fungal Ascomycota, and protist Conosa. Changes in the total abundance of bacteria, fungi, and protists, and their community structures in soils with organic fertilisers were associated with increases in soil organic carbon and phosphorous. Additionally, microbial networks exhibited greater complexity in organically fertilised soils than in non-organically fertilised soils by possessing higher linkage density. The increased complexity may be attributed to potential interkingdom associations among bacteria, fungi, and protists in high soil organic carbon and phosphorus. These results highlight that the application of organic fertilisers has the potential to enhance the complexity of microbial coexistence in acidic agricultural soils.

Soil microbes are important for nutrient cycling and ecosystem functions in diverse farmland systems. Intercropping systems alter the soil microbial community structure and boost metabolic function via biological interactions between species. However, the responses of microbial communities to nutrient limitation under intercropping conditions remain unclear. In this study, intercropping of proso millet and mung bean was used to investigate the microbial community structures and metabolic characteristics of both species rhizospheres. The relationship between microbial communities and nutrient limitation was analyzed using high-throughput sequencing. Compared with single cropping, the potential nitrogen (N) limitation of rhizosphere soil microorganisms of both species was more intense in intercropping. Linear regression analysis of soil nutrients, microbes, and threshold elemental ratios directly supported this finding. The soil microbial community diversity and composition were significantly affected by intercropping. Redundancy analysis revealed that total carbon:total nitrogen (TC:TN) and β–1,4–glucosidase: (β–1,4–N–acetylglucosaminidase + leucine aminopeptidase) (BG: (NAG + LAP)) ratios were key factors influencing bacterial and fungal community structure. Intercropping altered the topological network properties of soil microbial communities; the ecological connectivity of bacterial taxa was tighter than that of fungi. As dominant microbial communities, the increased relative abundance of Proteobacteria in intercropped mung bean and decreased relative abundance of Ascomycota in intercropped proso millet was conducive to regulating microbial metabolic limitations. Our results highlighted the close relationship between microbial communities and nutrient limitation, improving our understanding of the degree of plant–soil interactions from the perspective of microbial metabolism in proso millet/mung bean intercropping system.

In the last 50 years, humans have increased crop yields due to intensive agricultural practices and by homogenizing cultivated lands (e.g., larger and more uniform fields). However, this land management practice has led to serious environmental issues, and now, the importance of heterogeneity and semi-natural landscape elements in production systems is acknowledged. Perennial habitats, such as flower strips, could play a key role in agroecosystem sustainability, but little is known about their effects on earthworm and enchytraeid (Annelida: Oligochaeta) communities. The aim of this study was to assess earthworms and enchytraeids in 2.5-year-old wildflower strips that were sown in the middle of arable fields in northern France. Samples (soil, earthworms and enchytraeids) were collected at ten locations, in flower strips and in adjacent cropped fields. The same number of earthworm species was found in both habitats, but more enchytraeid species were detected in the flower strips than in the adjacent cropped fields. Moreover, the total abundance of earthworms and enchytraeids significantly increased in the flower strips compared with the adjacent cropped fields, by 69 % and 61 %, respectively. Flower strips had a significant positive effect on anecic and endogeic earthworms but not on the abundance of epigeic earthworms, which was highly variable among the samples, although on average, it was seven times greater in the flower strips than in the cropped fields. Although the flower strips were sown only 2.5 years earlier, significant changes were observed in the soil Oligochaeta communities. These findings advocate for sowing flower strips within cultivated land as a source of soil biodiversity in the current changing environment. Considering the positive role of flower strips on biodiversity and particularly on the studied tiny soil engineers, these perennial landscape elements should be more widely considered to support the agroecological transition.

Comammox Nitrospira represents a groundbreaking discovery in nitrogen cycle research, showcasing its remarking ability for complete ammonia oxidation, which challenges prior conceptions of nitrification. In this study, we examined the response of comammox Nitrospira gene abundance, diversity, and community structure to different rates of pig manure substitution (0 %, 25 %, 50 %, 75 %, and 100 %) in subtropical agroforestry soils. The abundance of ammonia-oxidizing microorganisms was assessed by qPCR, whereas the diversity and structure of comammox Nitrospira were determined by high-throughput sequencing. Our findings revealed that pig manure substitution led to an increase in soil pH, available phosphorus (AP), comammox Nitrospira abundance, and diversity within soils under Cinnamomum camphora coppice planting. Soil pH and AP were the primary factors influencing the diversity and community structure of comammox Nitrospira. Moreover, pig manure substitution significantly influenced the composition of comammox Nitrospira, notably by increasing the relative abundance of clade A.2.1 while reducing that of clade A.2.2. However, pig manure substitution did not exert a significant impact on net nitrification rates, suggesting bacterial relative abundances were more sensitive to manure substitution compared to the underlying biogeochemical processes. Overall, our results offer new insights into the response of comammox Nitrospira to different rates of pig manure substitution in Cinnamomum camphora coppice planting soils, highlighting the pivotal role of soil AP and pH as the key determinants shaping comammox Nitrospira diversity and community structure.

The National Earthworm Recording Scheme (NERS) is the most comprehensive national database of earthworm species occurrence records for the British Isles, and possibly for any individual country in the world. Utilising the NERS database, we sought to update the current knowledge of earthworm species occurrences in the UK, Ireland and Channel Islands; identify species-specific habitat and microhabitat associations; reveal any biases and complementarities between amateur naturalist and research-related earthworm record collection; and inform how future earthworm sampling can be better focussed to improve our knowledge of earthworm ecology. We found that the most commonly occurring earthworm species were present in farmland and woodland, and recovered via soil pit sampling, the most common habitat-sampling protocol combinations. However, several earthworm species showed specificity to alternative habitats (such as trees, wetlands, and compost), and association with microhabitat (non-soil) sampling. There were clear disparities between scientific researchers and amateur naturalist recorders in terms of habitat types visited and sampling protocols/microhabitats used in the collection of earthworm records. Most importantly, we found that earthworm species currently considered to be nationally ‘rare’ in the British Isles are significantly associated with the most under-represented habitat-protocol/microhabitat combinations (forest deadwood and other microhabitats, in addition to scrubland, wetland and heathland habitats), and thus may not be rare, only under-sampled. We therefore encourage earthworm researchers and recorders to give greater attention to these situations, to gain new insights into these earthworm species' ecologies and distributions. Finally, we would like to promote the establishment of earthworm recording schemes in other countries, to enable national and global collaborative monitoring of earthworm responses to environmental change.

Plant-associated beneficial microorganisms play a vital role in promoting plant health, fitness, and disease suppression, leading to improved plant growth and protection against specific plant parasites. Microbial amendments may reduce nematode parasite populations and ensure plant yield, yet their long-term impact on the native plant microbiome under field conditions is not well understood. In this study, we evaluated the effectiveness of biocontrol products against soybean cyst nematode (SCN) using two application methods over a two-year period under field conditions. Pochonia chlamydosporia PC10 (Rizotec), Bacillus methylotrophicus UFPEDA 20 (Onix), and Trichoderma koningiopsis GF 362 were applied either through seed inoculation or in-furrow treatment at planting. The treatments effectively reduced the nematode population, with T. koningiopsis showing significant deviations from the control and leading to a notable increase in yield. No difference in the Shannon diversity index was detected for the alpha-diversity of root-associated 16S, ITS2, and 18S communities. The dominant phyla were Proteobacteria, Acidobacteria, Actinobacteria for 16S; Ascomycota, Basidiomycota, Mortierellomycota for ITS2; and Ascomycota, and Cercozoa for 18S. In the 16S community, T. koningiopsis and B. methylotrophicus caused a 25 % increase in the relative abundance of Sphingomonas spp. compared to the control. Additionally, the relative abundance of Mortierella spp. significantly increased by 50 % in both the T. koningiopsis and B. methylotrophicus treatments compared to the control. Both treatments also led to a significant reduction in Fusarium spp. by 37.5 % and 31.5 %, respectively. Co-occurrence network analysis revealed that communities were disrupted after the first application, but grew more intricate and cohesive after the second year of biocontrol product amendment. T. koningiopsis and B. methylotrophicus demonstrated potential in reducing nematode and Fusarium populations, leading to increased yield production. However, under high nematode pressure, relying solely on biocontrol measures does not guarantee a reduction in SCN population or yield improvement. Manipulating the microbial community to reduce harmful organisms and promote biocontrol-related species may offer long-term benefits.

The impact of microplastics (MPs) on soil organisms is still a growing field, yet very little is known about the exposure of ultraviolet (UV) aging of MPs to soil organisms. In this study, we explored the response of the epigeic earthworm Eisenia andrei to pristine and UV-aged polyethylene (PE-MP) exposure at a wide range of environmentally relevant concentrations (0, 0.2, 2, 20, 200 and 2000 mg kg⁻¹) in an organic farm soil for 56d and assessed changes in reproduction, ingestion, egestion and gut microbiome. Results showed that exposure to 20 mg kg⁻¹ pristine PE-MP significantly increased earthworm reproduction by 39 % but the same concentration decreased reproduction by 29 % when they were exposed to UV-aged PE-MP. Ingestion of PE was verified by staining the whole worm body and their casts after 48h of starvation. The amounts of PE-MP found in the body and the casts were positively correlated with PE-MP concentrations in the soil, however only significantly so with pristine PE-MP. A decline in E. andrei gut microbiome alpha diversity and a significantly different community composition were observed in UV-aged PE-MP exposures compared to pristine PE-MP. Relative to the control treatments, Proteobacteria increased up to 135 %, Actinobacteria increased up to 35 %, and Firmicutes decreased up to 38 % under UV-aged PE-MP exposure, whereas Cyanobacteria increased up to 19 times in the pristine PE-MP treatments. These results confirm the negative effect of UV-aged PE-MP on earthworms even at low concentrations and could have important implications in the well-functioning of agricultural soils.

Soil organic phosphorus (OP) mineralization plays a vital role in the ecological restoration of roadside slopes. However, the changes in the functional bacterial (phoD-harboring) community involved in OP mineralization in soil aggregates during slope restoration are still unknown. In this study, a space-for-time substitution was conducted to compare the differences in the phoD-harboring bacterial community structure and assembly in soil aggregates of four particle sizes (<0.053, 0.25–2, 0.053–0.25, and >2 mm) at different slope restoration ages (7, 11, and 14 years). The results showed no significant differences in the phoD-harboring community diversity and structure among soil aggregates in the same restoration year. Community structure dissimilarity increased with restoration time. Species replacement dominated slope soils restored for 7, 11, and 14 years, accounting for 78.40 %, 79.68 %, and 68.96 % of the total β-diversity, respectively. Community assembly processes shifted from coexisting deterministic (68 %) and stochastic (32 %) processes in the 7-year restoration slope soil to dominantly deterministic (98 % and 91 %) processes in the 11- and 14-year restoration slope soils, respectively. Dominant phoD-harboring bacteria tended to shift from r-to K-strategies as slope restoration progressed, and the C:P ratio significantly correlated with both community structure and assembly. The increasing C:P ratio over restoration time stimulated phoD-harboring bacteria to secrete alkaline phosphatase to improve P availability, enhancing the complexity and stability of the network. This study elucidates the changing patterns of phoD-harboring bacteria in soil aggregates and provides a theoretical basis for the management of soil P during roadside restoration.

Chinese fir (Cunninghamia lanceolata) is the most important conifer tree species in plantations in subtropical China. Soil extracellular enzyme activities (EEAs) play key roles in mediating multiple forest ecosystem functions, such as organic matter decomposition, nutrient cycling, and plant productivity. In this study, the activities of five soil extracellular enzymes and their stoichiometric (EES) features were investigated at eight Chinese fir plantation locations. The results showed that the soil EEAs exhibited distinct biogeographic differences and were primarily affected by the spatial heterogeneity of soil nutrients. We found that the soil EES was strongly influenced by soil pH and mean annual temperature. Moreover, soil properties were found to be more important than climatic factors in influencing changes in soil microbial nutrient restrictions based on vector length (0.43 vs. −0.1). Random forest analysis indicated that changes in microbial nitrogen (N) and phosphorus (P) limitations were mainly affected by soil NO₃⁻-N and dissolved organic carbon (DOC), whereas soil microbial C limitation was largely influenced by pH, DOC, and total C content. This study sheds light on how soil and climatic factors affect soil EES in subtropical Chinese fir plantation ecosystems and provides useful insights for the development of management strategies to improve the productivity of Chinese fir forests.