Search Results (350)

This study assessed the feasibility of cultivating Lavandula dentata in Technosols produced from fine and coarse coal mining waste, focusing on plant development, substrate functionality, essential oil production, and post-mining ecosystem restoration. The Technosols were formulated using coal waste from the Moatize Coal Mine, Mozambique, combined or not in different configurations with agricultural soil and amended with sewage sludge (3% organic matter) and chemical fertilizer to ensure adequate nutrient availability. The experiments were conducted in 30 L containers, performed in triplicate for each experimental group. All settings allowed good plant growth, although the treatment that used only fine waste presented the closest performance to agricultural soil in terms of the production of aerial biomass. In this case, the dried biomass production of the shoots reached an average of 165 g per pot over 8 months (with a standard deviation of 20.3). The study showed a positive correlation between plant development and the available water capacity of the substrates. The plant tissue of L. dentata, in all the Technosols configurations studied, presented a similar composition to the control, with a biomass composition within the standard range established by the literature. The essential oil production ranged from 0.3 to 0.7% (m/m), averaging 0.5% (m/m), with chemical characteristics also alike the control trial. Technosols composed of coal waste from Moatize appear to be an alternative, both to provide a suitable destination for mining waste and to provide conditions for the revegetation and recovery of degraded areas by coal mining. This avoids the commissioning of nearby areas to supply soil for the restoration process. L. dentata, in addition to its various medical, ornamental, and aromatic uses, has potential as an “ecological trigger” in the restoration process with environmental and socioeconomic benefits. Full article

In permanently submerged coastal wetlands, interactions between biogeochemical processes and microbial communities strongly influence greenhouse gas (GHG) fluxes. To improve our understanding of how redox-driven processes shape GHG dynamics in these ecosystems, we investigated the relationships among iron (Fe) pools, microbial dynamics, and the potential GHG production in subaqueous soils from an interdunal wetland in San Vitale Park (Italy), permanently submerged and affected by seasonal oscillations of the saline water table. Two subaqueous soil columns (WAS-2 and WAS-4), collected from similar settings, were analyzed. Surface layers of WAS-4 showed higher salinity and carbonate content, whereas WAS-2 was characterized by overall higher Fe concentrations. Distinct vertical distributions of organic matter and sulfur (S) were shown along depth. Laboratory incubations revealed that nitrous oxide (N₂O) production was up to ten times higher in WAS-2 than in WAS-4, with peaks in the top 13–14 cm, consistent with more active nitrification-denitrification in surface layers. Methane (CH₄) and carbon dioxide (CO₂) fluxes decreased with depth, reflecting reduced availability of labile carbon. Methanomicrobiales dominated CH₄-producing layers, indicating hydrogenotrophic methanogenesis, while amoA-carrying Nitrosomonadales and Thaumarchaeota, occurred in shallow, organic-rich layers where ammonia supported nitrification and denitrification. Denitrifiers mainly belonged to α- and β-Proteobacteria, consistent with their direct contribution to N₂O peaks. Spearman’s correlations showed N₂O positively correlated to sulfur and labile carbon (C), supporting denitrification under moderately reducing conditions. CH₄ and CO₂ positively correlated with organic C (Corg), total nitrogen (TN), and reactive Fe forms, reflecting redox-mediated microbial respiration and methanogenesis. Trace elements (B, Cr, Cu, Ni) acted as micronutrients or inhibitors depending on concentration. Canonical correspondence analysis indicated depth-structured links among gas fluxes, soil chemistry (Corg, TN, S/C, CaCO₃, P), and microbial distributions: surface layers, rich in labile C and nutrients, supported active bacteria and archaea involved in decomposition, nitrification, and denitrification, whereas deeper layers hosted oligotrophic archaea adapted to inorganic substrates. Overall, Fe pools appeared to be associated with soil processes relevant to GHG dynamics, although the extent of their regulatory role remains uncertain due to potential alterations of redox-sensitive Fe fractions during sample handling. These results contribute to broader efforts to predict GHG emissions in submerged wetland soils by linking redox stratification, inorganic chemistry, and microbial functional groups. Full article

This study investigated the effects of different application rates of spent mushroom substrate (SMS) from Morchella sextelata on soil properties and microbial communities in a moso bamboo (Phyllostachys edulis) plantation. Three SMS rates (2.4, 4.7, and 9.4 kg·m⁻²) were applied, and soil samples were collected at 6 and 12 months from two depths (0–20 cm and 20–40 cm). One year after application, topsoil total phosphorus (TP) increased 12–20 fold, while available phosphorus (AP) and potassium (AK) were significantly elevated. Soil pH initially decreased but partially recovered, whereas electrical conductivity (EC) continued to rise, indicating salt accumulation. Urease (UA) and sucrase (SA) activities increased 10–17 fold and 3–5 fold, respectively, while catalase (CAT) and acid phosphatase (ACP) were temporarily suppressed. SMS application significantly altered microbial community composition, with Acidobacteriota and Basidiomycota becoming more abundant. Correlation analysis identified pH, organic matter, AP, and UA as key factors linked to microbial changes. The medium application rate (4.7 kg·m⁻²) provided the best balance between soil improvement and environmental risk. These findings demonstrate that M. sextelata SMS can effectively enhance soil fertility while modulating microbial communities, but salt accumulation and short-term acidification warrant attention. Full article

High-altitude mine wastelands in Southwest China present formidable challenges for ecological rehabilitation due to extreme climatic stressors and multi-element contamination. Ecological restoration is closely related to soil environment. However, the mechanism by which parent material-induced heterogeneity governs spontaneous vegetation succession is still poorly understood. We established 36 plots (216 quadrats) to investigate the soil physical and chemical properties and vegetation restoration of propylite, porphyry and siltstone in the Xifanping Copper Mine, Sichuan Province. Furthermore, fifteen metal/metalloid elements (Au, Ag, Mo, W, Cu, Pb, Zn, Hg, As, U, Se, Cr, Sn, Ti, Total Fe₂O₃), soil pollution and vegetation structure were evaluated. The study area exhibited severe composite pollution (mean Nemerow integrated pollution index = 8.09), primarily driven by Au, Ag, Mo, W, and Cu. Vegetation surveys identified 34 vascular plant species from 12 families. Propylite-derived substrates supported significantly higher species richness, Shannon–Wiener diversity, and soil organic matter than porphyry and siltstone. Redundancy analysis (RDA) identified soil organic matter (SOM) and bulk density (BD) as dominant environmental filters, with SOM explaining 14.03% of community variance (p < 0.01). Two native pioneers, Potentilla supina and Cynoglossum wallichii, were identified as specialized uranium (U) accumulators with bioconcentration factors of 13.39 and 4.49, respectively. Lithological inheritance dictates early successional trajectories by influencing edaphic structure and nutrient bioavailability. The identified U-accumulating species provide a valuable genetic resource for implementing Assisted Natural Regeneration (ANR) and developing sustainable phytoremediation strategies in contaminated alpine ecosystems. Full article

More efficient use of nutrients by crops and their reduced dispersion in the environment are essential elements of sustainable agriculture. The purpose of the present experiment was to determine the effects of mineral (N_min) and spent mushroom substrate (SMS) nitrogen on Festulolium braunii yield, but also on the uptake of that chemical element, use efficiency, and its accumulation in the soil. Results indicated that organic waste applied together with mineral fertilizers increased plant utilization of nutrients, their soil content and, consequently, the yield. SMS was applied once at the beginning of the experiment at three levels: SMS₁—10; SMS₂—15; SMS₃—20 Mg·ha⁻¹, supplying plants with 75, 112, and 150 kg N·ha⁻¹. Supplementary mineral nitrogen was applied at three levels as well: N₁—30; N₂—68; N₃—105. Additionally, 180 kg N·ha⁻¹ was applied without SMS (N₄). Treatment significantly affected grass yield, daily growth, and productivity of 1 kg of nitrogen. Their values were the highest on the N₂ + SMS₂ plot (68 + 112 kg N·ha⁻¹). Nitrogen content was the highest in grass treated with mineral nitrogen without SMS (N₄). When the share of SMS nitrogen was higher, its content in the biomass was lower. The absorption of nitrogen (Nup) and its use efficiency (NUE) by plants on the plots with SMS and mineral fertilizers (105 + 75 kg N·ha⁻¹, as well as 68 + 112 kg N·ha⁻¹) were similar to the values recorded on the plot with mineral nitrogen only (N4). After two years, there was no increase in total nitrogen soil accumulation as a result of applied treatment. Mushroom substrate nitrogen allowed for a reduction of nitrogen fertilizer doses by 40 to even 60%. Such fertilizer treatment fits into the closed economy model based on minimizing the consumption of raw materials and on increasing environmentally friendly waste disposal. Full article

The poor quality and scarcity of soil used for raising seedlings are key issues holding back the further development of the rice industry. Artificial humic substances (A-HS) and artificial soils are attracting increasing attention due to their cost-effectiveness and significant potential to improve rice cultivation. This study used native soil (NS), engineered soil (ES) and rice straw to create artificial substrates (AES and ANS) using humification–hydrothermal carbonization technology (24 h treatment of NS and ES with rice straw at 200 °C and 2 MPa). Experiments on cultivation of the rice seedlings were conducted using initial soils (ES and NS) and artificial soils with addition of A-HS (AES+A-HS and ANS+A-HS). This study examined the nutrient content and microbial environment of the seedling substrates as well as the changes in growth and development of the rice seedlings. The combination of rice straw biochar in artificial soils (AES and ANS) with A-HS significantly increased the content of soil organic carbon (SOC) and enhanced the nutrient levels, such as total nitrogen and available phosphorus. Furthermore, it enhanced the microbial diversity, and it increased the abundance of microorganisms such as Actinomycetota, Chloroflexota, and Basidiomycota, thereby improved the soil microbial environment. An enhanced soil nutrient content and improved microbial environment effectively promoted the rice seedling growth. Compared to the original soils (ES and NS), before transplanting to paddy fields, the stem width of the seedlings increased by 5.1% (AES+A-HS) and 10.2% (ANS+A-HS), and their height increased by 18.7% (AES+A-HS) and 4.5% (ANS+A-HS). The rice seedling emergence increased by 6.1% (AES+A-HS) and 3.9% (ANS+A-HS), and the transplant survival rate also increased by 4.1% (AES+A-HS) and 2.9% (ANS+A-HS). This study provides an effective approach to alleviating the scarcity of rice seedling substrates and improving the quality of rice seedlings, and it provides an effective foundation for increasing the yield of rice. Full article

The lunar surface soil (regolith) represents a potential substrate for crop cultivation in future extraterrestrial bases. However, the absence of indigenous microbial activity severely limits nutrient availability in lunar soil. In this study, the effects of three commercial microbial fertilizers on improving simulated lunar soil and promoting lettuce (Lactuca sativa L.) growth were experimentally evaluated. The results showed that microbial fertilizers significantly increased the contents of available nutrients (N, P, and K) and organic matter in simulated lunar soil, thereby enhancing lettuce growth and biomass accumulation. Compared with the treatment without adding microbial fertilizer application (CK), the aboveground and belowground fresh weights of lettuce increased by up to 91.61% and 89.08%, respectively, under the microbial fertilizer MLQ treatment. In addition, microbial fertilizer treatment increased nutrient accumulation and photosynthetic pigment contents in lettuce, alleviated oxidative stress by improving antioxidant system performance, and consequently enhanced lettuce quality. High-throughput sequencing analysis further revealed that the dominant bacterial genera under these conditions were Bacillus, Glutamicibacter, Acetobacter, Enterococcus, and Microbacterium, while the dominant fungal genera included Saccharomyces, Pichia, and Trigonopsis. These findings provide theoretical support for the development of functional microbial fertilizers tailored for simulating lunar soil. Full article

Montane forests are commonly limited by phosphorus (P) scarcity, yet Rhododendron species persist via specialized P-acquisition strategies. However, the microbial processes governing P utilization among wild Rhododendron species remain unclear. We collected soil and root samples from three wild Rhododendron species—Rhododendron latoucheae Franch. (R. latoucheae), Rhododendron fortunei Lindl. (R. fortunei) and Rhododendron simsii Planch. (R. simsii)—in a montane forest and analyzed soil P fractions, acid phosphatase activity, and fungal community traits to investigate their relationships with P cycling. The results showed significant differences in P fraction contents between non-rhizosphere and rhizosphere soils among the three species. In R. fortunei, rhizospheric NaOH-Po decreased tenfold while H₂O-Pi increased by 9.13 mg/kg, indicating a shift toward labile P. In contrast, R. latoucheae and R. simsii showed increases in moderately labile P by 32.54% and 22.09%, respectively. R. latoucheae exhibited the lowest acid phosphatase activity in non-rhizosphere soil (4.810 ± 0.560 μmol/d/g), which increased significantly in the rhizosphere. Fungal community analysis revealed a significant enrichment of Podila in the rhizosphere of R. latoucheae (10.84%) and R. simsii (9.17%), while Penicillium (6.80%), Trichoderma (3.65%) and Mortierella (5.83%) were dominant in the R. fortunei rhizosphere. R. latoucheae mineralized organic P through acid phosphatase hydrolysis driven by nutrient scarcity. R. fortunei likely mobilizes inorganic P through ericoid mycorrhizal-associated secretion of organic acids and the activity of specialized phosphate-solubilizing fungi facilitated by high substrate availability. Soil nutrients (SOC, TN, $\mathrm{N}{\mathrm{O}}_3^{-}$-N) influenced fungal abundances and indirectly shaped soil P fractions, whereas fungal taxa abundance in the rhizosphere directly drove P turnover. Our results confirm that different wild Rhododendron species employ distinct P-acquisition strategies mediated by rhizosphere fungi and enzyme activities, and provide new insights into microbial-driven P cycling in montane forests. Full article

Straw and cattle manure are common agricultural wastes, and their composting plays a critical role in regional nutrient cycling and organic carbon management. During composting, the structural evolution and humification processes of dissolved organic matter (DOM), fulvic acid (FA), and humic acid (HA) are regulated by environmental factors such as temperature and pH. However, systematic studies on the multi-component fluorescence characteristics of DOM in straw–manure systems and their coupling with environmental variables remain limited. In this study, maize straw and cattle manure were used as raw materials, with four mixing ratios (T1–T4: 2:8, 4:6, 6:4, and 8:2), to investigate the effects of raw material proportions on the structural evolution of DOM, fulvic acid (FA), and humic acid (HA) during composting. Three-dimensional fluorescence spectroscopy combined with parallel factor analysis (EEMs-PARAFAC) was applied to characterize organic components, their transformation patterns, and their relationships with environmental factors. The EEMs-PARAFAC identified 3, 2, and 3 components for DOM, FA, and HA, respectively. Moderate straw–cow manure ratios (T2 and T3) maintained high microbial activity while promoting humic-like component accumulation and FA-to-HA conversion. Fluorescence indices indicated mixed substrate-derived and microbial sources for DOM, predominantly microbial origins for FA, and a shift in HA from substrate-derived to mixed sources. Overall, humification remained low (humification coefficient < 1.5), reflecting an early composting stage. Mantel analysis and partial least squares path modelling (PLS-PM) revealed temperature as the dominant factor associated with HA formation, whereas an alkaline pH inhibited humification. These findings clarify how substrate ratios regulate humification via environmental microhabitats, providing a theoretical basis for optimizing straw–manure co-composting and enhancing compost stability and soil carbon sequestration. Full article

Utilizing bamboo residues for the cultivation of Stropharia rugosoannulata is an ecological practice grounded in the concept of agricultural waste recycling, aiming to improve soil microecology and enhance nutrient cycling in bamboo forests. However, a comprehensive and systematic evaluation of the ecological effects of using bamboo residues as cultivation substrates is lacking. To evaluate soil responses following the cultivation of S. rugosoannulata, a field experiment was conducted using bamboo residues pre-fermented with 4% rapeseed cake. The results showed that cultivating S. rugosoannulata with rapeseed cake-fermented bamboo residues significantly enhanced soil nutrient levels and enzyme activities. Notable increases were observed in soil organic carbon, total nitrogen, available nitrogen, and total potassium, as well as in the activities of sucrase, urease, peroxidase, polyphenol oxidase, and neutral protease. Both bacterial and fungal α-diversity were significantly enhanced, and substantial shifts occurred in the community structure and composition of soil microbiota. Metabolomic analysis revealed that significantly differential metabolites were primarily enriched in five key pathways, including purine metabolism, glycerolipid metabolism, biosynthesis of plant secondary metabolites, and starch and sucrose metabolism. Correlation analyses further revealed that specific microbial taxa (four bacterial genera and seven fungal genera) exhibited strong correlations with soil nutrient indicators, whereas another group of taxa (six bacterial phyla and eight fungal genera) was closely linked to soil enzyme activities. Furthermore, bacterial communities were significantly correlated with metabolite variations after substrate addition. Specifically, Firmicutes showed strong positive correlations with multiple metabolites, whereas Planctomycetes exhibited negative correlations with some of the same metabolites, indicating potential competitive interactions. Based on these findings, this study proposes a preliminary “Microbe–Enzyme–Metabolite–Nutrient” coupling cycle, driven by the synergistic interplay among bamboo residues, hypha–microbiome complex, soil enzymes, and functional metabolites. This mechanism provides a scientific explanation for the soil health improvements observed during S. rugosoannulata cultivation and offers theoretical support for the efficient utilization of bamboo waste and maintenance of forest ecosystem stability. Full article

To assess digestate’s efficacy as a fertilizer for basil development, a two-year pot experiment was established, comprising four fertilization treatments: namely, mineral fertilizer (F), digestate (D), combined mineral fertilizer and digestate (1:1, FD), and unfertilized control (C). Key metrics assessed included plant height, chlorophyll concentration index (CCI), total biomass (TB), leaf production (LP), essential oil yield, and composition. Post-harvest analysis evaluated nutrient and heavy metal content and pathogen contamination in the growing substrate and leaves. FD treatment produced the highest TB (68.2 g plant⁻¹) and LP (52.7 g plant⁻¹). Digestate application substantially enhanced substrate nutrient availability, increasing extractable phosphorus by 68.5%, potassium by 134.4%, and organic matter by 54.7%. The essential oil yield was significantly higher in the control plants. whereas different fertilization regimes altered secondary metabolite synthesis. Specifically, fertilization with digestate favored sesquiterpenes synthesis, inorganic fertilization enhanced methyleugenol and β-farnesene synthesis, and the control showed higher limonene, eugenol, and linalool. Heavy metal accumulation in the growing substrate was negligible, remaining well within regulatory limits. Salmonella spp., were not detected. Pathogen concentration in the growing substrate was low, while Enterococcus faecalis levels were marginally below EU safety limits (100 cfu g⁻¹) on the leaves. Continuous monitoring of soil chemical properties and plant products after digestate application is essential to ensure soil health and food safety. Full article

In response to the problems of loose soil structure and insufficient water and nutrient retention capacity of sandy bank slopes in arid regions, which constrain vegetation establishment and long-term slope stability, this study focuses on typical sandy soils in arid northwestern China. The desert plant Alhagi sparsifolia, characterized by clonal root sucker reproduction, was selected as the study species to construct and optimize a composite-amended sandy substrate suitable for ecological restoration of bank slopes. Based on an orthogonal experimental design, carboxymethyl cellulose sodium (CMC), straw fibers (SF), and fly ash (FA) were combined at different proportions to assess (i) the vertical distribution of soil water and nutrients in the A. sparsifolia growth habitat, (ii) aggregate structure, (iii) plant trait responses to environmental regulation, and (iv) the shear strength of root–soil composites. The results indicate that when the contents of CMC, SF, and FA were 0.5%, 1.0%, and 5.0%, respectively, the substrate environment promoted a vertically oriented root system with pronounced lateral root development in A. sparsifolia, and the plants adopted an adaptive strategy that balances resource acquisition efficiency and environmental constraints by regulating aboveground growth allocation. This growth pattern reduced the risk of disturbances to slope stability caused by excessive aboveground biomass while maintaining the sand-fixing function of root morphological traits. This study provides a plant functional trait-based regulation strategy for ecological restoration of typical sandy slopes in arid regions, and the proposed composite substrate optimization scheme offers a feasible reference for improving vegetation establishment and substrate performance in sandy habitats. Full article

Mollisols represent foundational agricultural soils in which high organic carbon (C) and active microbiomes sustain fertility and mediate global C cycling. However, decades of intensive cultivation have depleted soil organic C (SOC) and degraded soil structure and function. Enhancing C sequestration in agricultural Mollisols through the incorporation of organic residue, such as crop residues, organic waste, and spent mushroom substrates has become an urgent scientific and management priority. This review integrates advances from the past decade, combining stable isotope probing, multi-omics analyses, and ultrahigh-resolution molecular characterization to elucidate how microorganisms mediate C sequestration during organic residue return and decomposition. We propose a four-dimensional conceptual framework, “substrate–microenvironment–metabolic pathway–residue stabilization,” that links microbial metabolism with long-term C persistence in Mollisols. We further highlight that organic residue inputs promote CO₂ sequestration via fermentation–autotrophy coupling, nitrifying autotrophy, and microbial mixotrophy. Major C sequestration pathways operate synergistically across redox microenvironments, forming stratified metabolic networks that sustain continuous C cycling. The chemical composition and decomposition kinetics of organic residue governs substrate and energy fluxes for microbial C sequestration, while soil redox status, and nutrient coupling (Carbon–Nitrogen–Phosphorus–Sulfur) collectively direct C flow toward stabilization. Microbial necromass and extracellular polymers achieve long-term C storage through mineral adsorption and microaggregate formation. Finally, we summarize recent methodological advances for tracing microbial CO₂ sequestration in agricultural Mollisols and identify key research needs on residue formation, C use efficiency, and aggregate-mineral protection mechanisms. This synthesis establishes a mechanistic foundation for biologically regulated C management and offers guidance for sustainable cropland restoration. Full article

The rapid increase in organic waste generation poses significant environmental challenges and highlights the limitations of conventional waste management practices. In this context, black soldier fly (Hermetia illucens) larvae (BSFL) have emerged as a promising biological tool for valorizing organic residues within circular bioeconomy frameworks. This review provides an integrated analysis of BSFL-based bioconversion systems, focusing on the biological characteristics of BSFL, suitable organic waste streams, and the key process parameters influencing waste reduction efficiency, larval biomass production, and frass (the residual material from larval bioconversion) yield. The performance of BSFL in converting organic waste is assessed with emphasis on substrate characteristics, environmental conditions, larval density, and harvesting strategies. Environmental and economic implications are discussed in comparison with conventional treatments such as landfilling, composting, and anaerobic digestion. Special attention is given to the nutritional composition of BSFL and their valorization as sustainable protein and lipid sources for animal feed and emerging human food applications, while frass is highlighted as a nutrient-rich organic fertilizer and soil amendment. Finally, current challenges related to scalability, safety, regulation, and social acceptance are highlighted. By linking waste management, resource recovery, and sustainable protein production, this review clarifies the role of BSFL and frass in resilient and resource-efficient food and waste management systems. Full article

Background: Hermetia illucens larvae provide a sustainable bioconversion pathway that transforms agro-industrial residues into protein- and nutrient-dense biomass and frass, suitable for animal feed and soil amendment, respectively. Nevertheless, the potential spread of antibiotic resistance (AR) genes and pathogenic microorganisms poses biosafety concerns. This study examined the impact of four residue-based diet formulations; peas and chickpea (D1), peas and wheat (D2), onion and wheat (D3), and wheat with digestate (D4), on microbial safety during the bioconversion process. Methods: Enterococcus spp. (viable counts), Salmonella spp. (presence/absence), and 13 AR genes associated with resistance to tetracyclines, macrolide-lincosamide-streptogramin B, β-lactams, vancomycin, and aminoglycosides were quantified in single substrates, diets, larvae, and frass using qPCR. Results: Principal component analysis revealed diet-driven AR gene profiles. D1 lowered the levels of the greatest number of tested AR genes, particularly erm(B), tetracycline, and β-lactam genes in frass, as well as tet(O) and vanB in mature larvae. In contrast, D2 increased the AR gene levels in frass. All diets except D4 eliminated Salmonella spp. Enterococcus spp. loads varied by diet and larval stage, with D2 reducing counts in frass. Conclusions: Diet composition directly shapes microbial dynamics and AR gene dissemination, indicating that legume-based substrates may enhance biosafety in bioconversion systems. Full article