European Journal of Soil Biology最新文献

Methane, the primary substrate for aerobic methanotrophs, regulates the rate of methanotrophic activity and shapes the composition of the methane-oxidizing community. Given that methane-derived carbon may fuel the food web in the soil, methane availability can potentially be a key determinant, structuring the network of the interacting methane-oxidizing community. Here, we determined the response of the methane-driven interaction network to different methane concentrations (∼1.5 %_v/v, 3 %_v/v, and 7 %_v/v), indicative of different levels of energy flow through the soil food web, using a stable isotope probing approach with ¹³C-methane coupled to a co-occurrence network analysis in a microcosm study. The accumulated ¹³C-atom fraction in the total carbon content increased from 1.08 % (background level) to an average of 7.2 % in the incubation under 7 %_v/v methane, indicating that the carbon-flow via the methanotrophs can significantly contribute to the total carbon in the rice paddy soil. The ¹³C-enriched 16 S rRNA gene sequencing analysis revealed the predominance of gammaproteobacterial methanotrophs and Methylocystis. The composition of the actively growing (¹³C-labelled) bacterial community was dissimilar in the incubation under ∼3 %_v/v than under 1.5 %_v/v and 7 %_v/v methane. This was also reflected in the co-occurrence network analysis, where the topological properties indicated a more complex and connected network in the incubation under 3 %_v/v methane. It thus appears that moderate methane concentrations fostered closer associations among members of the methane-oxidizing community. Overall, our research findings showed that the methanotrophs can contribute to the total soil carbon, and methane concentrations not only shifted the bacterial community, including the methanotrophic composition, but also affected bacterial interactions.

Olive is one of the largest crops in Spain, primarily for oil extraction from drupes. This process produces a by-product called ‘alperujo’, which can be composted and used as fertilizer. This study investigated the impact of ‘alperujo’ compost on ground/soil invertebrate inhabitants compared to mineral fertilization in two groves with different crop management types (superintensive and traditional) during 2021 and 2022. Anystidae/Erythraeidae (Acari; Trombidiformes) and Acari (Other) were more abundant in the compost treatment in both groves, but significant only in the superintensive grove. Some other ground/soil inhabitants, such as Anthicidae (Coleoptera), Araneae, and Gastropoda were generally more present in the compost treatment of the superintensive grove. No significant effect of fertiliser treatment was observed for other ground/soil organisms. Future studies with more replicas and over a longer period of time should be performed to confirm these results, but they can be considered of interest to push forward the implementation of ‘alperujo’ compost in the olive fertilization, favouring a circular economy and a sustainable agriculture.

Earthworms and enchytraeids are soil organisms involved in key soil functions, such as organic matter turnover and soil structure, at different scales. In natural soils, these organisms are exposed and sensitive to different abiotic factors (e.g., climate, land use and management) and are often used as bioindicators of human disturbances, particularly chemical stress. However, the sensitivity of these two groups of Oligochaeta (Annelida) to different stressors has never been compared. Using data from 49 publications and 330 observations, we performed a meta-analysis to compare the sensitivities of earthworms and enchytraeids to all kinds of stressors under similar test conditions. Earthworms and enchytraeids were found to be equally sensitive to chemical stressors (mean effect size −0.61 [-2.53; 1.30]) regardless of the studied endpoint (mortality or reproduction). Most of the observations dealt with the effects of pesticides (42 %) and heavy metals (40 %) on both organisms. No difference in sensitivity was revealed when these two stressors were considered separately. Regarding the two most studied species of enchytraeids and earthworms, the mean effect sizes of all the possible combinations of Eisenia fetida (41 % of the studies) or Eisenia andrei (48 %) or Enchytraeus crypticus (73 % of the studies) or Enchytraeus albidus (27 %) did not reveal any differences in sensitivity. This study also highlights the lack of studies on environmentally relevant (i.e., representative of natural soils) enchytraeid and earthworm species. We also revealed that mostly ecotoxicologists have compared the sensitivities of these two key soil organisms when they are exposed to and threatened by other important factors, such as agricultural practices and climate change.

Soil microbial community assembly processes and networks in croplands have been widely explored; however, their dynamics and how they regulate winter wheat yield across distinct soil aggregate fractions under the combined effects of mulching and soil horizons have not been comprehensively understood. Therefore, based on a 9-y field experiment, the responses of soil bacterial and fungal community assembly processes and interkingdom association networks to mulching were specifically investigated at the soil aggregation level. Soil properties and microbial biomass were separated into distinct mulching in the topsoil (0–10 cm), and soil water content was considered the most critical factor. The soil bacterial community was affected mainly by mulching and soil horizon compared with the fungal community in microaggregates (<0.25 mm). Notably, the bacterial community displayed more robust stochastic processes than the fungal one, and microbial interkingdom association networks were more complex and stable in micro-than macroaggregates. Soil potential carbon mineralization, pH, and total nitrogen were the dominant properties regulating winter wheat grain yield in combination with microbial community composition, assembly processes, and networks in each soil aggregate class. Wheat yield decreased under straw mulching and was mainly regulated by bacterial community composition and assembly processes. Thus, this study enhanced our understanding of the regulations for wheat yield, which could facilitate soil microbial community management at the aggregation level for sustainable crop production in mulching conservation agroecosystems.

Earthworms support and mediate the provision of many processes in the soil. They are therefore important in maintaining soil functioning and contribute towards the sustainability of soil management systems. Assessment of earthworm communities can provide answers regarding the land management conservation efforts and insight on soil quality. The main aim of this study was to assess the impact of farming (organic vs conventional) and tillage (no-tillage vs minimum tillage vs conventional tillage) systems on earthworm communities under varying soil conditions in arable fields across Estonia. To achieve this, we compiled data from studies carried out over a period of 21 years on Estonian arable fields. While organic farming and conventional farming showed a similar earthworm abundance, earthworm diversity was significantly higher (p < 0.05) under the organic system. Higher abundance, species richness, and the proportion of anecic species suggest that a no-tillage system creates the most favourable habitat conditions for earthworms. Soil texture further influenced the effect of management system on earthworm abundance and diversity indexes. For example, the differences in earthworm abundance and diversity between the management systems increased from lighter textured to heavier textured soils. Our results suggest that soil texture is a major factor influencing earthworm communities in Estonian agricultural fields and emphasizes the importance of including different soil texture classes when assessing the effects of agricultural management practices in field-scale studies.

Complete ammonia oxidizers (comammox Nitrospira) are intriguing discoveries that mark a significant milestone in the global nitrogen cycle. While numerous soil physiochemical variables have been identified as key influencers of comammox Nitrospira distribution, the role of soil texture in shaping these communities remains largely uncertain. Here, we explored the diversity, community structure of comammox Nitrospira, and their driving factors, including soil texture in 237 rice-wheat rotation soils. The results indicated that soil pH and texture were the primary factors influencing the Shannon diversity and richness of comammox Nitrospira. Comammox Nitrospira Shannon diversity and richness were positively associated with soil pH and silt content, but negatively correlated with clay content, suggesting that finer-textured soils harbored lower comammox Nitrospira diversity. Additionally, silt content emerged as the second most influential factor, after pH, shaping comammox Nitrospira community structure. Clade A.2 was found as the predominant comammox Nitrospira clade in rice-wheat rotation soils, representing 59.3 % of the total sequences. Clade A.2 exhibited a positive correlation with sand and clay contents but a negative association with silt content. Conversely, Clades A.3 and B demonstrated the opposite pattern. Overall, our study underscores the critical role of soil texture as a mediator of comammox Nitrospira diversity and community structure, emphasizing the need to consider soil texture in investigations of comammox Nitrospira.

Soil microbial biomass carbon (MBC) and microbial entropy play a crucial role in the carbon cycle of terrestrial ecosystems, while their responses to soil properties in typical sloping croplands under the impact of soil erosion remain poorly understood due to the complexity of the soil erosion process. In this study, we selected typical sloping croplands with different erosion levels for the four severely eroded soil types (black, loess, purple, and red soil) in China to assess the key controls of MBC and microbial entropy under the influence of soil erosion. The results showed that soil erosion significantly reduced the MBC content but increased the microbial entropy of sloping croplands in black soil region (BS) (22 %, 43.6 %), purple soil region (PS) (25.5 %, 26.2 %) and red soil region (RS) (28.9 %, 21.9 %), but not in loess soil region (LS). The soil physicochemical properties had significantly positive and negative correlations on the MBC and microbial entropy, respectively. The MBC and microbial entropy of these sloping croplands had different dominant drivers under soil erosion. Overall, our results revealed that changes in MBC and microbial entropy directly depended on the fundamental properties of the soil and soil erosion could indirectly affect the MBC and microbial entropy by directly affecting the physicochemical properties of soil. Thus, the impact of soil erosion on sloping croplands and the associated responses following changes in MBC and microbial entropy provide fresh insights into predicting the effects of soil erosion on carbon stability.

Nitrifiers are the key player in the nitrogen cycle of agroecosystems, yet less research has focused on their performance and response in saline ecosystems. In this study, we carried out potting experiments with biochar and wood vinegar as saline soil amendments under rice cultivation conditions with four different treatments: without biochar or wood vinegar (CK), biochar (BC), wood vinegar (WV), and biochar + wood vinegar (BC + WV). The results showed that the addition of biochar and/or wood vinegar decreased the soil pH and electrical conductivity (EC), which led to an increase in the gene abundance of ammonia-oxidizing bacteria (AOB), thereby benefiting the advancement of the potential nitrification rate (PNR). WV and BC + WV significantly increased the gene abundance of Nitrospira. In addition, the addition of biochar and wood vinegar altered the community composition of ammonia-oxidizing archaea (AOA) and ammonia-oxidizing bacteria (AOB), while the NH₄⁺-N content was the key factor affecting the nitrifier communities. Compared to the CK group, biochar and/or wood vinegar significantly increased the relative abundance of Nitrosospira cluster 3 b in AOB and unknown affiliation in nitrite-oxidizing bacteria (NOB). Overall, the abundance and community composition of AOB contributed more to the PNR than those of AOA, while NOB played a pivotal role in the potential nitrite oxidation (PNO) rate in sodic saline soils. In conclusion, the addition of biochar with wood vinegar had positive effect on improving sodic saline soils by improving the physicochemical properties of the soils, increasing the abundance of nitrifier and changing the community structure of nitrifier. Exploration of the key drivers of soil nitrifier processes is potentially useful for understanding the biological potential of nutrient cycling, providing novel insight into the effects of human intervention and soil management.

In the initial stages of restoring areas affected by rocky desertification, plant survival is strongly influenced by nitrogen nutrition. Mycorrhization is a unique type of inter-root engineering that improves nitrogen acquisition efficiency by plant roots. We selected potted mulberry trees inoculated, two dominant arbuscular mycorrhizal fungi (AMF) with Funneliformis mosseae (Fm) and Rhizophagus intraradices (Ri), to clarify the effects of AMF on the root nitrogen content of mulberry trees. Meanwhile, the key factors of soil nitrogen changes caused by AMF were analyzed, based on the primary role of soil nitrogen as the source of root nitrogen. Simultaneously, the potential of AMF to promote the acquisition of different forms of nitrogen by mulberry roots was investigated. Our findings indicate that the inoculation of mulberry plants with Fm and Ri, improved plant height and increased nitrogen accumulation in the roots and shoots. Additionally, AMF regulates nitrogen transformation, significantly increasing soil nitrate nitrogen (NO₃⁻-N) and dissolved organic nitrogen (DON) levels. The results indicated that soil NH₄⁺-N, NO₃⁻-N, and DON contributed to the observed changes in root nitrogen accumulation. The largest contribution (22.0 %) to the overall effect size was made by NO₃⁻-N. AMF stimulated soil microbial activity and significantly increased soil glomalin-related soil protein (GRSP), enzyme activity, and soil microbial biomass (SMB). Urease activity and microbial biomass carbon (MBC) both increased exponentially by 118.7 % and 115.2 %, respectively. Higher GRSP, enzyme activity, and SMB were positively correlated with changes in soil nitrogen patterns, and GRSP had the most significant effect on changes in the soil nitrogen dynamics. Our study confirmed that inoculation with AMF not only regulates soil nitrogen dynamics but also diversifies plant nitrogen sources. This is achieved by increasing plant growth and enhancing soil microbial activity. Ultimately, this enhances plant root nitrogen nutrition. Therefore, AMF promote root nitrogen accumulation and enhance root nitrogen uptake through GRSP-regulated soil nitrogen, providing a theoretical basis for the management of rocky desertification.