Soil Organisms Research Articles

Restoration of fumigated soil biota with plant growth-promoting rhizobacteria to counteract Meloidogyne incognita (Tylenchida: Heteroderidae) boosts eggplant growth and defenses

AbstractThis study investigated the effectiveness of two plant growth-promoting rhizobacteria (PGPR) formulations, Bio Arc® 6% WP (BA, Bacillus megaterium) and BECTO Grow Roots® (BGR; Serratia marcescens, Pseudomonas putida, and P. fluorescens). Additionally, it focused on naturally infested soil that had undergone metam potassium fumigation to reduce root-knot nematode (RKN), specifically Meloidogyne incognita. It aimed to monitor eggplant response to soil biodiversity changes for 60 days of the experiment under greenhouse conditions. Our data showed that soil fumigation eliminated nematodes and reduced other microorganisms significantly. In sterilized soil, plant fresh root weight significantly decreased after the elimination of soil biota. Moreover, BGR achieved the highest plant growth vigor [fresh root (18.48%), fresh shoot (23.52%), and fresh plant weight (21.03%)], followed by BA [fresh root (11.98%), fresh shoot (20.77%), and fresh plant weight (16.38%), respectively]. Plant growth traits increased significantly following the second reinoculation of PGPR after a month. Also, the same data trend was observed in treatments inoculated with RKN + PGPR. Furthermore, BGR treatments exhibited consistent efficacy in controlling nematode infection, maintaining superior vegetative growth compared to BA treatments over time. However, BA treatments displayed a decline in plant growth when faced with repeated nematode infection. The range of gall, egg mass, and second-stage juvenile (J2s) numbers diminished after inoculation-infected plants with RKN and PGPR compared with infected plants alone. Biochemical changes in eggplant roots cultivated in sterilized soil exposed significant enhancement in total sugars, protein, and nonenzymatic antioxidants (flavonoids and phenolic content), with antioxidant activity enhanced upon inoculation of PGPR and RKN. Oppositely, the levels of enzymatic antioxidants (catalase, peroxidase, and superoxide dismutase) decreased significantly with single and double PGPR application. However, the decline was less pronounced in the BGR treatments than in BA. In contradiction of oxidative enzymes, reinoculated PGPR + RKN multiplied significantly in reinfested RKN treatments. Our findings support the use of PGPR combinations, in particular, for preventive inoculation against M. incognita. They also enhance plant growth-promoting factors and stimulate plant defenses against inevitable soil reinfestation following soil fumigation.

Diversified cropping strengthens herbivore regulation by providing seasonal resource continuity to predators

Abstract Agricultural practices shape arthropod communities in arable fields, consequently influencing their interactions and the resulting ecosystem services, in particular pest regulation. Predatory arthropods play a pivotal role by preying on herbivores, soil fauna, and on other predators. However, the intricate mechanisms through which agricultural practices shape the dietary preferences of predators, and regulate herbivore populations remain complex and inadequately understood. We assessed how fertilisation with organic fertiliser and extending crop rotations with perennial ley affected predation pressure across prey taxa. We mapped predator and prey trophic linkages with molecular analysis of carabid predator gut contents, and measured densities and taxonomic richness of predators, herbivores, and soil fauna in 19 cereal fields during three samplings across the growing season. We derived two food web structure metrics: prey vulnerability that is the average number of predators feeding on a selected prey, and predator trophic redundancy, that is dietary overlap. Prey vulnerability was compared among soil fauna, herbivores, and other predator species (that is interspecific intraguild predation) over the growing season, and across treatments. The mechanistic underpinnings of observed shifts in vulnerability of herbivorous prey at different crop stages were identified using information criteria to select among candidate variables related to the richness, density and interaction structure of the different guilds during both the current, and the previous crop stages. Agricultural diversification via organic fertilisation combined with perennial ley in the crop rotation decreased the vulnerability of both intraguild prey and soil fauna prey, and stabilised herbivore vulnerability. Mechanistically, the vulnerability of herbivorous prey at crop ripening emerges from the combination of predator richness and trophic redundancy during this sampling round, rather than from carryover effects from previous crop stages. Synthesis and applications: Our results suggest that locally provided resource continuity through diversified cropping practices bolster biological pest regulation, thus underline the importance of lesser disturbance in arable ecosystems for the provision of ecosystem services. Enhanced predator species richness together with availability of alternative prey through the season underpins this enhanced pest regulation.

Microbial Diversity and Nitrogen Cycling in Peat and Marine Soils: A Review

Nitrogen is an essential nutrient for living organisms in peat and marine soils, and its transformation within the soil matrix is a complex process mediated by various microbes that inhabit these ecological niches. The metabolism of nitrogen is governed by microbially mediated biogeochemical transformations, such as nitrification, anammox, and denitrification, which contribute to the assimilated pool of nitrogen and fixed nitrogen loss. One of the major challenges facing the field of peat and marine microbiology is the lack of understanding of the correlation between ecosystem-driven nitrogen transformation and microbial diversity. This is crucial because of growing concerns regarding the impacts of human-induced activities and global climate change on microbial nitrogen-cycling processes in peat and marine soils. Thus, this review aimed to provide a comprehensive overview of the current understanding of the microbial communities involved in peat and marine nitrification, anammox, and denitrification; the factors influencing the niche differentiation and distribution of the main functional components; the genes involved; and the main effects of human-induced activities and global climate change on the peat and marine nitrogen cycle. The implications of this review will facilitate an understanding of the complex mechanisms associated with ecosystem function in relation to nitrogen cycling, the role of peat and marine soils as carbon sinks, pollution remediation using naturally occurring populations of diverse microbes, and the development of policies to mitigate the effects of anthropogenic influences in peat and marine soils.

Impacts on Various Management Practices on Crops Yield and Soil Biology in Maize-Wheat Cropping System

Aims: Integrated approaches that consider the synergies and trade-offs among tillage, residue, and nitrogen management are essential for optimizing agricultural sustainability to highlight the complex interplay between agronomic, environmental, and biological factors. We intended to evaluate the impact of tillage, residue, and nitrogen management on crop growth and soil biological properties under a maize-wheat cropping system in an inceptisol. Study Design: Split-split plot design. Place and Duration of Study: ICAR-IARI research farm, New Delhi, since 2014. Methodology: We collected soil samples at the anthesis stage of wheat crop and silking stage of maize crop at 0-5, 5-15, and 15-30 cm soil depth. Soil properties, namely soil organic carbon, dehydrogenase, acid, and alkaline phosphatase, soil microbial biomass carbon, soil microbial biomass phosphorus, and glomalin content by using standard procedures. Results: We observed that the soil organic carbon, enzyme activities, microbial biomass carbon and phosphorus, and glomalin content were significantly (P<0.05) higher under no-tillage and residue treatment at 0-5 and 5-15 cm soil depth. Enzyme activity and microbial biomass carbon (MBC) were significantly higher by application of 100 and 150% RDN, respectively, at 0-5 and 5-15 cm soil depth. The effect of nitrogen treatment on biomass yield was significant (P<0.05) and found to be higher at 150% Recommended dose of Nitrogen (RDN). The biomass yield of maize was 15.3% and 44.5%, and wheat was 7.8% and 20.4%, significantly increased by applying 150% RDN over the 100% and 50% RDN respectively. Conclusion: Farmers can successfully adopt NT with 5 t ha-1 crop residue mulch with 150% RDN to attain better soil health and higher biomass yield under the maize-wheat cropping system.

Transformation and Degradation of PAH Mixture in Contaminated Sites: Clarifying Their Interactions with Native Soil Organisms

Soil contamination of polycyclic aromatic hydrocarbons (PAHs), especially caused by the mixture of two or more PAHs, raised great environmental concerns. However, research on the migration and transformation processes of PAHs in soils and their interactions with native communities is limited. In this work, soil samples from uncontaminated sites around the industrial parks in Handan, Hengshui, and Shanghai were artificially supplemented with three concentrations of anthracene (Ant), 9-chloroanthracene (9-ClAnt), benzopyrene (BaP), and chrysene (Chr). Ryegrass was planted to investigate the degradation of PAHs and its interaction with native soil organisms in the constructed ryegrass–microbe–soil microcosmic system. The bacterial and fungal communities in soil were affected by PAHs; their species diversity and relative abundance changed after exposure to different concentrations of PAHs, among which Lysobacter, Bacillus, Pseudomonas, and Massilia bacteria were correlated to the degradation of PAHs. On the 56th day, the contents of BaP, Chr, and Ant decreased with the degradation process, while the degradation of 9-ClAnt was limited. Nineteen intermediates, including hydroxylation and carboxylated compounds, were identified. The present research would help clarify the potential interactions between PAHs and native organisms in contaminated sites, providing fundamental information for evaluating the transformation risks of PAHs in the natural environment.

Moving towards a mechanistic understanding of biostimulant impacts on soil properties and processes: a semi-systematic review

Biostimulants are gaining prominence in scientific research, with the potential to enhance plant productivity through benefits to crop yield/quality and tolerance to environmental stresses. Through possible improvements to nutrient use efficiency, they may also lessen the adverse environmental impacts of conventional inorganic fertilizer use in agriculture. The application of biostimulants is currently uncommon as a farming practice, with uncertain effectiveness in delivering these potential benefits. Current research focuses on biostimulant effects on plant physiological changes. There is little scientific evidence on the impact of biostimulants on soil properties (biological, physical, or chemical) or soil functions. This knowledge gap should be addressed considering the vital role of soil processes in the bioavailability of nutrients, as reflected in crop productivity. This review evaluates laboratory and field experimental work on the effectiveness of common, non-microbial biostimulants, with a focus on their modes of action within the soil matrix. Of 2,097 initial articles returned through the search strings, 10 were within the scope of this review. A common soil biostimulant mechanism emerges from this literature. This relates to the supply of nutrients provided by the biostimulants, which stimulate native soil microbiology in mineralizing organic material in the soil, thus producing more bioavailable nutrients for plant uptake. Additionally, some articles link biostimulant effects to soil physical and chemical changes, which in turn impact soil biology (and vice versa). However, there is inconsistent evidence to provide full support for these explanatory mechanisms. This review highlights the need for further research into the effect of biostimulants on the native soil microbiology and associated soil properties, to provide greater clarity on biostimulants’ modes of action and greater mechanistic insights into how they can be used to improve crop production.

Micro Plastic Pollution in Soil Environment: A Comprehensive Review

Plastic is a substance that is fundamental to current human existence. However, the issue of plastic trash polluting the environment has emerged due to the rapidly growing demand for plastic use. Even though some used plastics are recycled or burned for energy, a significant amount of plastic waste is landfilled or released into marine and terrestrial habitats worldwide. Particularly, trash made of microplastics smaller than 5 mm is regarded as a rising global problem for contamination. Nonetheless, the majority of studies on the effects of microplastic pollution conducted in the previous ten years have been on the marine ecosystem, with relatively few on the terrestrial ecology. One may argue that soil serves as both a significant source of microplastic pollution and a conduit for it into the aquatic ecosystem. The majority of microplastic sources in soil settings enter through a variety of openings, fragment, and spread both vertically and horizontally to the surrounding surroundings. Additionally, there are detrimental effects on the soil biota, which could influence the food web and raise questions about human health. This overview of microplastics' properties, research trends, analytical techniques, migration and degradation processes, impacts on soil biogeochemistry, and interactions with soil organisms highlights the significance of continuing studies on the effects of microplastics on terrestrial ecosystems.

Land disposal of dredged sediments from an urbanized tropical lagoon: toxicity to soil fauna.

Urban tropical lagoons are commonly impacted by silting, domestic sewage and industrial wastes and the dredging of their sediments is often required to minimize environmental impacts. However, the ecological implications of land disposal of dredged sediments are still poorly investigated in the tropics. Aiming to contribute to filling this gap, an ecotoxicological evaluation was conducted with dredged sediments from Tijuca Lagoon (Rio de Janeiro, Brazil) using different lines of evidence, including soil and sediment characterization, metal determination, and acute and avoidance bioassays with Eisenia andrei. Two different dredged sediment samples, a sandy sediment and another muddy one, were obtained in two distinct and spatially representative sectors of the Tijuca Lagoon. The sediments were mixed with an artificial soil, Ferralsol and Spodosol to obtain doses between 0 (pure soil) and 12%. The sediment dose that caused mortality (LC50) or avoidance responses (EC50) to 50% of the organisms was estimated through PriProbit analysis. Metal concentrations and toxicity levels were higher in the muddy sediment (artificial soil LC50 = 3.84%; Ferralsol LC50 = 4.58%; Spodosol LC50 = 2.85%) compared to the sandy one (artificial soil LC50 = 10.94%; Ferralsol LC50 = 14.36%; Spodosol LC50 = 10.38%), since fine grains tend to adsorb more organic matter and contaminants. Mortality and avoidance responses were the highest in Spodosol due to its extremely sandy texture (98% of sand). Metal concentrations in surviving earthworms were generally low, except sodium whose bioaccumulation was high. Finally, the toxicity is probably linked to marine salts, and the earthworms seem to accumulate water in excess to maintain osmotic equilibrium, increasing their biomass.

Why are graminoid species more dominant? Trait‐mediated plant–soil feedbacks shape community composition

AbstractSpecies traits may determine plant interactions along with soil microbiome, further shaping plant–soil feedbacks (PSFs). However, how plant traits modulate PSFs and, consequently, the dominance of plant functional groups remains unclear. We used a combination of field surveys and a two‐phase PSF experiment to investigate whether forbs and graminoids differed in PSFs and in their trait–PSF associations. When grown in forb‐conditioned soils, forbs experienced stronger negative feedbacks, while graminoids experienced positive feedbacks. Graminoid‐conditioned soil resulted in neutral PSFs for both functional types. Forbs with thin roots and small seeds showed more‐negative PSFs than those with thick roots and large seeds. Conversely, graminoids with acquisitive root and leaf traits (i.e., thin roots and thin leaves) demonstrated greater positive PSFs than graminoids with thick roots and tough leaves. By distinguishing overall and soil biota‐mediated PSFs, we found that the associations between plant traits and PSFs within both functional groups were mainly mediated by soil biota. A simulation model demonstrated that such differences in PSFs could lead to a dominance of graminoids over forbs in natural plant communities, which might explain why graminoids dominate in grasslands. Our study provides new insights into the differentiation and adaptation of plant life‐history strategies under selection pressures imposed by soil biota.

Crop management strategies shape the shared temporal dynamics of soil food web structure and functioning

In recent decades, there has been growing interest in exploring the soil biota, highlighting the significance of soil organisms' networks in soil functioning. Here, we use a modeling approach to investigate how changes in cropping practices influence the soil food web dynamics and it relates to that of soil functioning. In an experimental trial, we tested for change in topsoil food webs after shift from conventional to alternative practices (changes in tillage intensity, amount of residues returned and N fertilization rate). Samplings were made in 16 plots of a randomized complete block design during spring of year 0, 2 and 4 after the onset of the trial. Microorganisms, microfauna, mesofauna and macrofauna were sampled, identified and grouped into trophic groups. We built a general soil food web describing plausible carbon flows between these trophic groups and computed several network indices. At the same dates, soil functions linked to C and N dynamics were measured from soil samples. We used a COSTATIS analysis to investigate relationships between temporal sequences of soil functions and soil food web indices. Significant interactive effects of the date and of agricultural systems were found on the mean and the maximum trophic level, the bacterial-to-fungal path ratio, the total biomass and the way biomass accumulates across trophic levels, the number of trophic groups and the functional redundancy in trophic groups. Similarly, organic matter transformations and enzymatic activities showed differences across date and agricultural systems. Results show that temporal changes in soil food web structure and in soil processes related to N and C cycling co-vary following changes in agricultural management practices. Management practices related to tillage exerted stronger effects on soil food web functioning than those related to the export of crop residues or reduction in mineral N fertiliser. For instance, reduced tillage lead to more complex food webs, with increased C and N mineralization in the upper soil layer (0–5 cm), in which most of the residues accumulate. Our results provide insights on soil food webs temporal dynamics, even within a restricted panel of agricultural practices. Our results suggest that changes in agricultural practices influence feedbacks between organisms and the functions they perform, so that a temporal co-structure can be observed in the studied site. Such work could help better understand the mechanisms of resistance or ecological debt during agroecological transition, which could limit or delay expected Nature-based solutions.

Current Status of Research on Wildland Fire Impacts on Soil Environment and Soil Organisms and Hotspots Visualization Analysis

Ecosystems are frequently disturbed by fires that have an important impact on the soil environment and the composition of soil organisms. In order to provide a baseline for the current research and identify trends on the effects of wildland fire on soil environment and biological changes, the available literature was identified from the Web of Science database, covering the period from 1998/1998/1999 (the year of the earliest publication in this field) to 2023. A bibliometric analysis was performed and the data were visually displayed for the number of publications, countries, authors, research institutions, and keywords representing research hotspots. Specifically, the effects of wildland fire on the soil environment, on soil microorganisms and on soil fauna were analyzed. The results show that the annual number of publications describing effects of wildland fire on the soil environment and on soil microorganisms are increasing over time, while those describing effects on soil fauna are fewer and their number remains constant. The largest number of papers originate from the United States, with the United States Department of Agriculture as the research institution with the largest output. The three authors with the largest number of publications are Stefan H. Doerr, Manuel Esteban Lucas-Borja and Jan Jacob Keizer. The research hotspots, as identified by keywords, are highly concentrated on wildfire, fire, organic matter, and biodiversity, amongst others. This study comprehensively analyzes the current situation of the research on the effects of wildland fire on changes in the soil environment and organisms, and provides reference for relevant scientific researchers in this trend and future research hotspots.

Cow Based Inputs for Sustainable Agriculture: A Review

Food safety is of prime importance at present because the consumption of food products with chemical residues above the threshold levels is causing dreadful diseases in living beings and deteriorating soil health too. The current global scenario firmly emphasizes the need to adopt agricultural practices that are ecologically safe for sustainable food production. Hence, it is necessary to adopt organic farming which improves the health of Agro-ecosystems besides providing safe food and conserving the soil fertility and soil biota. There is a need to identify a suitable substitute in place of chemical fertilizers which are economically cheaper and ecofriendly. In this context, Cow-based inputs (dung, urine, ghee, milk) play an important role in organic farming as an alternative to chemical fertilizers which help in the growth of the crop and provide eco-safety food

Soil and Vegetation Characteristics of Grassland have a Greater Influence on the Abundance and Diversity of Earthworms than the Mowing Intensity in a Managed Nature Reserve

Effects of mowing on vegetation parameters have been well studied. However, less is known about mowing effects on soil fauna and if soil properties alter this. We investigated earthworm communities in a long-term experiment 14 years after its establishment in 5 dry, fresh and moist grassland plots located in the Natura 2000 site Lainzer Tiergarten near Vienna, Austria (238–402 m a.s.l., 48°10′ N, 16°12′ E). The grasslands were either mowed once a year or every second year, or not mowed since being established. Earthworms were assessed using the non-destructive octet electro-shocking method. Additionally, vegetation composition, soil conductivity, temperature and moisture were assessed. We found 13 earthworm species across all treatments, although their abundance was generally low with 6.1 ± 4.7 worms m−2. The total earthworm abundance and species diversity was higher in dry compared to fresh and moist grasslands but was not affected by mowing frequency. Endogeic earthworms (Aporrectodea caliginosa, Aporrectodea rosea) and epigeics (Lumbricus rubellus) were more tolerant to mowing than anecics (Lumbricus terrestris, Allolobophora longa). Since plant species richness was highest in annually mown grasslands and earthworm species richness was positively related to plant species numbers, we recommend regular, low-input management to promote above- and belowground biodiversity in these grasslands.

Effects of reduced snowpack due to climate warming on abiotic and biotic soil properties in alpine and boreal forest systems

Reduction in snow cover, depth, onset, and duration of seasonal snow in mid-latitude regions due to climate warming has multiple global and local scale ecosystem impacts. These effects include modulations of the hydrological cycles and increases in land surface solar radiation absorption due to decreased albedo. Changes in snow cover characteristics also affect underlying soils. Snow has an insulating effect on soils by decoupling air and soil temperatures, thus seasonal snow cover reduction leads to overall lower soil temperatures and an increase in freeze-thaw cycles. This is especially prominent during the fall and spring thaw seasons when the snow cover is not as extensive. This in turn has downstream impacts on soil physical, chemical, and biological properties. Among these impacts are soil moisture reduction, temperature, frost regimes, soil pH shifts, and alteration in nutrient flux dynamics during winter, snowmelt period and the following summer growing season. These changes in soil physicochemical properties due to snowpack reduction can then impact the biological soil properties via increased plant root mortality, reduced abundance and diversity of soil arthropods, and shifts in composition, abundance and activity of soil microbial communities. All these soil biotic factors can in turn alter the dynamics of soil nutrient fluxes and future greenhouse gas emissions. Here, we integrate data on the effects of snow cover reduction on abiotic and biotic soil properties, with focus on temperate alpine and forest ecosystems and with an outlook on future impacts.

Contour prairie strips alter microbial communities and functioning both below and in adjacent cropland soils

Prairie strips are narrow strips of native, perennial vegetation (10–40 m width) integrated within cropped fields to provide benefits for water quality and biodiversity. However, the impact of prairie strips on soil microbial communities and function, both underneath the prairie strips and in the adjacent cropland, is not known. We assessed the effect of restoring native perennial vegetation on soil C and N, potential enzyme activities (PEA), and microbial community composition in the soil directly underneath and cropland adjacent (0.1 to 9 m) to 12-year-old prairie strips integrated within row crop fields. We found that prairie strips consistently increased soil microbial biomass carbon (>56 %) and altered PEA in complex ways. Generally, prairie strips increased hydrolase and decreased oxidoreductase PEA. Prairie strips also changed the soil microbial community directly under prairie vegetation, and, contrary to the expectation that greater plant diversity leads to greater soil microbial diversity, prairie strips reduced bacterial and fungal diversity. The prairie strip's effect on adjacent cropland soils depended on year, but it was strong when it occurred and was typically independent of distance from the prairie strip. Prairie strips increased PEA in adjacent soils (<9 m) by as much as 38 % and shifted bacterial and fungal beta diversity, but neither showed patterns with distance from the prairie strip, indicating that prairie strips cause field-scale shifts in soil biota and functioning, and these effects are not mediated by proximity to the prairie strip. Understanding the mechanisms underlying prairie strips' impact on soil biota, both underneath and adjacent to the prairie, is key to optimize their agroecosystem benefits.

Meta-analysis reveals that the effects of precipitation change on soil and litter fauna in forests depend on body size.

Anthropogenic climate change is altering precipitation regimes at a global scale. While precipitation changes have been linked to changes in the abundance and diversity of soil and litter invertebrate fauna in forests, general trends have remained elusive due to mixed results from primary studies. We used a meta-analysis based on 430 comparisons from 38 primary studies to address associated knowledge gaps, (i) quantifying impacts of precipitation change on forest soil and litter fauna abundance and diversity, (ii) exploring reasons for variation in impacts and (iii) examining biases affecting the realism and accuracy of experimental studies. Precipitation reductions led to a decrease of 39% in soil and litter fauna abundance, with a 35% increase in abundance under precipitation increases, while diversity impacts were smaller. A statistical model containing an interaction between body size and the magnitude of precipitation change showed that mesofauna (e.g. mites, collembola) responded most to changes in precipitation. Changes in taxonomic richness were related solely to the magnitude of precipitation change. Our results suggest that body size is related to the ability of a taxon to survive under drought conditions, or to benefit from high precipitation. We also found that most experiments manipulated precipitation in a way that aligns better with predicted extreme climatic events than with predicted average annual changes in precipitation and that the experimental plots used in experiments were likely too small to accurately capture changes for mobile taxa. The relationship between body size and response to precipitation found here has far-reaching implications for our ability to predict future responses of soil biodiversity to climate change and will help to produce more realistic mechanistic soil models which aim to simulate the responses of soils to global change.

The ConSoil project: An integrated framework for monitoring plant protection product residues in agricultural soil

AbstractPlant Protection Products (PPPs) are widely used to maintain high productivity and protect crops, but can have unintended toxic effects on beneficial non‐target soil organisms. To avoid unacceptable adverse effects of PPPs on soil organisms, a prospective risk assessment is carried out, which focuses on individual substances and their effects on a few individual species or groups. However, the reality of agricultural soils consists of complex networks of organisms exposed to mixtures of several PPP active substances. It is therefore essential to monitor PPP residues in soils. This paper describes the ConSoil project and its proposed framework for monitoring PPP residues in Swiss Agricultural soils which includes and integrates (1) risk‐based reference values for PPP residues in soil and (2) indicators of their effects on long‐term soil fertility. For risk‐based reference values, a proposal has been developed to derive Soil Guideline Values (SGVs) for PPP residues and a mixture risk assessment concept is being developed. Regarding indicators, a toolbox of ecological and ecotoxicological indicators will be proposed to reflect the protection goal of long‐term soil fertility in agricultural soils. For this objective, standardised and/or well‐established bioindicator methods will be selected for the key soil organisms that support soil fertility. To integrate SGVs and the biomonitoring toolbox, an adapted TRIAD approach is proposed, where generic SGVs are used as a screening tool to identify monitoring sites potentially at risk and to trigger more detailed monitoring. Detailed monitoring will refine the SGVs based on site‐specific characteristics and implement the bioindicator toolbox to measure the effects of PPP residues and their risk to long‐term soil fertility. As a novel integrated framework, it is essential to use the data generated in detailed assessments to calibrate and refine the SGVs and bioindicator tools and improve the monitoring over time.

Occurrence of Sphingomonas olei with elemental S oxidation capability in sodic soil: Potential role in sodicity reclamation and plant growth promotion

The success of the sodic soil reclamation using elemental S (S°) depends on the population of the native S° oxidizers. Augmenting the native flora of the sodic soils with effective S° oxidizers can enhance the success of the sodic soil reclamation. Present study reports for the first time the S° oxidation potential of the Sphingomonas olei strain 20UP7 isolated from sodic soils with pHs 9.8 and ECe 3.6 dS m–1. Inoculation with S. olei strain 20UP7 caused 13.0–24.2 % increase in S° oxidation in different sodic soils (pHs 9.1–10.5). It improved the concentration of the Ca2+, Mg2+, PO43– and declined the HCO3– and total alkalinity of the soil solution. This isolate also showed appreciable P and Zn solubilization, indole acetic acid, ammonia, and titratable acidity production in the growth media. It tended to the formation of biofilm around sulphur particles. The PCR amplification with gene–specific primers showed the occurrence of soxA, soxB, and soxY genes with a single band corresponding to length of 850, 460, and 360 base pairs, respectively. The integration of the S. olei strain 20UP7 with S° caused 21.7–25.4 % increase in the rice and wheat yield compared to the soil treated with S° alone. This study concludes that the S. olei, native to high saline–sodic soils can be utilized for improving the sodicity reclamation and plant growth promotion using elemental S based formulations.

Limited dependence on soil nitrogen fixation as subtropical forests develop

Soil nitrogen (N) fixation, driven by microbial reactions, is critical to support the entrance of nitrogen in nutrient poor and pioneer ecosystems. However, how and why N fixation and soil diazotrophs evolve as forests develop remain poorly understood. Here, we used a 60-year forest rewilding chronosequence and found that soil N fixation activity gradually decreased with increasing forest age, experiencing dramatic drops of 64.8% in intermediate stages and 93.0% in the oldest forests. Further analyses revealed loses in diazotrophic diversity and a significant reduction in the abundance of important diazotrophs (e.g., Desulfovibrio and Pseudomonas) as forest develops. This reduction in N fixation, and associated shifts in soil microbes, was driven by acidification and increases in N content during forest succession. Our results provide new insights on the life history of one of the most important groups of soil organisms in terrestrial ecosystem, with consequences for understanding the buildup of nutrients as forest soil develops.

Impacts of Soil Management and Sustainable Plant Protection Strategies on Soil Biodiversity in a Sangiovese Vineyard

Vine growing is one of the most economically important sectors of Mediterranean agriculture, but its cultivation practices are highly detrimental to the environment and the associated biota. The application of both natural products inducing endogenous plant defense mechanisms and natural soil management systems represents a potential solution for the preservation and improvement of soil health and biodiversity. The Life Green Grapes project aimed at evaluating the effects of different natural and sustainable vine protection strategies and soil management on vineyard edaphic communities. Soil TOC, TN, C:N ratio, CaCO3 content and pH were measured. Microbial communities (bacteria and fungi) were characterized through NGS, while nematodes and microarthropods were isolated and identified. Obtained data highlighted a relationshipbetween bacteria, fungi and nematodes with soil chemistry, and an effect of the different soil management on the single and total edaphic communities. Network analysis evidenced a positive effect of the application of sustainable soil managements on the relationships among the different investigated soil trophic levels, suggesting that more natural soil managements allow a better interaction between soil organisms. In conclusion, this work confirms the importance of the application of sustainable and natural soil management practices in agricultural ecosystems, with the aim of conserving and improving soil biodiversity.