We conducted a field experiment to investigate the effects of biochar derived from three feedstocks (pig manure, peanut shell, and maize straw) on the nutrient limitation status of soil microbial communities and the abundance of functional genes involved in organic carbon degradation in a Phyllostachys edulis forest. Each biochar was applied at a rate of 20 t·hm-2, with soil without biochar amendment as control. We measured soil and microbial properties after two years. The results showed that all biochar types significantly increased soil pH, soil organic carbon, total phosphorus, and available phosphorus contents. Pig manure biochar significantly reduced soil C:P and alleviated the stoichiometric imbalance between microbial biomass and soil resources. All biochar treatments significantly increased β-glucosidase activity (by 46.5%-131.1%) but decreased the activities of β-N-acetylglucosaminidase (by 20.6%-51.1%) and acid phosphatase (by 23.1%-56.4%). Biochar application significantly intensified microbial carbon limitation while reduced phosphorus limitation and decreased microbial carbon use efficiency, with the most pronounced reduction being observed under pig manure biochar. Biochar application significantly increased the abundances of functional genes of starch, hemicellulose, cellulose, pectin and lignin degradation, following the order of pig manure biochar > peanut shell biochar > maize straw biochar. Random forest analysis indicated that soil total phosphorus and available phosphorus contents were the key factors influencing microbial carbon limitation. Partial least squares path modeling (PLS-PM) indicated that biochar inputs increased microbial carbon limitation by elevating soil pH and alleviating the C:P imbalance, which in turn reduced carbon use efficiency. The degree of microbial carbon limitation exhibited a significant positive effect on the abundance of micro-bial carbon degradation functional genes. In conclusion, biochar from different feedstocks could regulate microbial nutrient limitation by altering soil pH and nutrient stoichiometric balance, thereby affecting microbial carbon metabolic efficiency.

Moso bamboo (Phyllostachys edulis) expansion into subtropical forests can alter rhizosphere soil organic carbon (SOC) formation and stabilization, but how these effects differ between soil organic matter fractions and neighboring tree species with contrasting mycorrhizal associations remains unclear. Here, we investigated SOC partitioning between particulate organic matter (POM) and mineral-associated organic matter (MAOM) in the rhizospheres of neighboring Pinus massoniana (ectomycorrhizal, ECM) and Schima superba (arbuscular mycorrhizal, AM) trees at the moso bamboo expansion front. We quantified soil chemical properties, microbial biomass, microbial residue carbon (MRC), glomalin-related soil protein (GRSP), and microbial life-history strategies in both POM and MAOM fractions. MAOM-SOC increased by 75% and 137%, whereas POM-SOC declined by 25% and 15%, in the rhizospheres of P. massoniana and S. superba, respectively, at the expansion front relative to the unexpanded forest. MAOM-associated TN, AP, and TP increased by 46%–125% in both tree rhizospheres. The chemical recalcitrance index (FTIR 1630/1030) decreased in MAOM. Together, these changes suggest that moso bamboo expansion altered C partitioning between POM and MAOM in neighboring tree rhizospheres. Microbial responses differed between MAOM and POM: MAOM-associated total PLFAs (102%–131%), total MRC (67%–71%), T-GRSP (11%–90%), and bacterial r-strategists (19%–21%) all increased at the expansion front. By contrast, POM-associated total MRC declined by 30% in S. superba and T-GRSP by 32% in P. massoniana. Notably, relative increases in MAOM-SOC and MAOM-GRSP were greater in S. superba than in P. massoniana, indicating species-specific responses of neighboring trees with contrasting mycorrhizal associations. Overall, moso bamboo expansion altered rhizosphere C partitioning between POM and MAOM, with responses shaped by microbial byproducts, microbial life-history strategies, and the contrasting mycorrhizal associations of the neighboring tree species.

Soil heavy metal(loid) pollution remains one of the most critical environmental challenges worldwide, and increasing attention has been paid to remediation strategies. Phosphate-solubilizing microorganisms (PSMs) have been identified as promising bioremediation microorganisms due to their multifunctional roles in nutrient cycling and heavy metal(loid) stabilization or mobility. This review provided the remediation mechanisms of heavy metal(loid)-contaminated soils by PSMs, including surface adsorption, chelation with siderophores, organic acids, and exopolysaccharides. During the remediation process, PSMs could also enhance the soil available phosphorus which could further immobilized heavy metal(loid)s. The PSMs could also combine with hyperaccumulators and soil amendments to increase the remediation efficiency through altering the bioavailability of heavy metal(loid)s. The remediation efficiency of PSMs could be influenced by soil characteristics, environmental conditions, and heavy metal(loid) properties, which relate with the PSMs activity. The PSMs application may also result in soil acidification, disrupt the native microbial communities, and increase the mobilization of heavy metal(loid)s, which could not be ignored. This work will provide guidelines for the safe and effective remediation of metal(loid)-contaminated soils using PSMs. Future research should aim to optimize PSM application on enhancing the remediation efficiency of contaminated soils and decreasing the ecological risks.

Continuous cropping severely limits the sustainable production of watermelon (Citrullus lanatus L.) by inducing soil degradation, yet the mechanisms of microbial succession and interaction remain unclear. We monitored rhizosphere soils across 11 consecutive cropping seasons in a greenhouse pot experiment to evaluate the impact on bacterial and fungal communities. Available nitrogen, available potassium, total carbon, and total nitrogen declined with cropping duration, whereas available phosphorus showed a hump-shaped pattern. Soil pH reached a minimum in the seventh season, and soil enzyme activities increased markedly from the fifth season. Quantitative Real-time PCR (qPCR) and amplicon sequencing showed sustained rises in bacterial abundance, while fungal abundance initially decreased before recovering. Bacterial Shannon diversity hit a nadir in the fifth season with subsequent partial recovery, whereas fungal diversity continuously declined. Principal coordinate analysis (PCoA) revealed abrupt community shifts in both domains at the fifth season. Co-occurrence networks simplified sharply thereafter, with bacterial network complexity strongly negatively correlated with enriched Bacillus abundance (R² = 0.91). Structural equation modeling indicated that soil chemical changes and reduced fungal diversity were associated with increased Fusarium, whereas Bacillus enrichment did not suppress Fusarium. Sterilized soil bioassays confirmed that biotic factors induced broad-spectrum growth inhibition in both watermelon and tomato, suggesting broader microbial community imbalance. These results identify the fifth season as a critical threshold for Fusarium enrichment and network simplification, highlighting an actionable time window for early interventions to restore microbial functions before dysbiosis becomes entrenched.

Organic substitution for chemical fertilizer and inoculation of phosphate-solubilizing bacteria (PSB) benefit sustainable agriculture, yet their individual or combined effects on soil stoichiometry and phosphorus (P) fractions accumulation remains poorly understood. Here, a 6-year field experiment was set up with four fertilization regimes, including no fertilizer (CK), chemical fertilizer (CF), partial organic substitution (POS) of chemical fertilizer with compost manure, and POS together with PSB inoculants (MOF). Compared with the CF, both POS and MOF increased rice yield and P uptake but had weak effects on soil total carbon (C), nitrogen (N) and P contents after six years. The MOF significantly increased dissolved organic C and decreased microbial biomass C:P ratio, resulting in an increased C:P imbalance between microorganisms and their resources compared with POS. Though both POS and MOF increased the accumulation of soil recalcitrant P fraction compared with the CK, MOF significantly decreased the accumulation of residual P and NaHCO3-Pi in comparison with the POS treatment. Solution 31P NMR spectra analysis revealed that MOF remarkably increased phosphate monoesters accumulation and their proportion compared to the CF. POS increased the relative abundances of the functional genes and enzyme activities involved in cellulose and hemicellulose degradation, while MOF increased those of organic P mineralization. Partial least squares path modeling suggested that changes in C:P imbalance play a key role in affecting P accumulation by affecting microbial composition, the organic C and P related degradation genes and enzymes activities. Our study suggests that partial organic substitution and its inoculation with PSB induced divergent effects on P fractions accumulation by changing C and P related function, providing insight into the potential mechanisms of organic management on P mobilization in future agriculture production.

Mitigating methane (CH4) emissions from paddy fields without compromising yield remains a critical challenge for sustainable agriculture, primarily due to trade-offs between emission reduction and nutrient availability. Biochar-based fertilizer (BF), which integrates biochar with mineral nutrients, may address this constraint by regulating carbon and nitrogen availability. This study evaluated the effects of biochar-based fertilization on CH4 emissions and rice productivity. A one-season field experiment was conducted in Hydragric Anthrosols with four treatments: no fertilization (control), conventional chemical fertilization (CF), integrated application of biochar-based and chemical fertilizers (CBF), and biochar-based fertilizer alone (BF). Methane fluxes were monitored alongside soil physicochemical properties and the abundances of key functional microbial genes. Compared with CF, BF significantly reduced cumulative CH4 emissions by 23.24% while maintaining comparable rice yield, resulting in a 28.67% reduction in yield-scaled CH4 emissions. Biochar-based fertilization decreased dissolved organic carbon availability, buffered NH4+-N concentrations, and increased soil pH. These changes shifted the microbial balance of CH4 cycling, suppressing methanogenesis and enhancing methane oxidation, as reflected by a lower mcrA/pmoA ratio. Structural equation modeling indicated that CH4 mitigation was jointly driven by reduced methanogenic activity and enhanced methane oxidation. Overall, biochar-based fertilization regulates soil chemical and microbial processes to mitigate CH4 emissions without yield penalties, demonstrating strong potential as a scalable and field-applicable strategy for low-carbon rice production.

Intensive management of Carya cathayensis (C. cathayensis) plantations has been linked to soil degradation and increased disease incidence, yet the underlying shifts in rhizosphere microbial communities remain poorly understood. We compared rhizosphere soils from non-managed forest(NF), reduced-management forest(RF), and intensive-management forest(IF) stands across two towns in Zhejiang, China. With increasing management intensity, soil fertility and enzyme activities declined, bacterial diversity and network stability decreased, whereas fungal diversity tended to increase. Bacterial community assembly was predominantly deterministic and became more so under intensive management, whereas fungal assembly remained largely stochastic. Management intensity did not directly regulate microbial assembly; instead, soil chemical properties and enzyme activities mediated these patterns. Several microbial taxa responded strongly to management intensity and were significantly correlated with community assembly processes. These findings reveal consistent associations between management intensity and rhizosphere microbial patterns across two landscapes, despite potential site-related variation. Reducing management intensity favours microbial network complexity and stability, offering microbiome-based avenues for sustainable C. cathayensis forestry.

Phosphorus (P) availability influences the spatial distribution of carbon (C)-cycling enzyme activities in the rhizosphere through its effects on plant growth and microbial activity. However, the influence of P availability on the spatial patterns of C and P hydrolase activities remains unclear in the rhizosphere of Maize (Zea mays L.) and narrow-leaf lupine (Lupinus angustifolius L.), which exhibit contrasting P deficiency adaptation and acquisition strategies. This study analyzed the spatial patterns of C and P hydrolase activities through zymography and correlated them with bacterial community structure in maize and lupine rhizospheres. Under P-deficient conditions, maize exhibited severe growth restriction while demonstrating a 2.2-9.6-fold increase in root exudation compared to P-sufficient conditions. The enhanced exudation under P deficiency promoted r-strategist bacterial proliferation (e.g., Ktedonobacteria and Xanthomonadales) while reducing K-strategist abundance (Actinobacteriota, Chloroflexia, and Alphaproteobacteria). Maize rhizosphere enzyme activities and hotspot areas demonstrated positive correlation with K-strategist abundance and negative correlation with r-strategist abundance. P-sufficient maize exhibited 15-550% higher C-and P-cycle-related enzyme activity and hotspot areas, attributed to its enhanced root system and predominance of K-strategists with superior enzyme synthesis capabilities. Lupine demonstrated superior P deficiency adaptation, producing 2-19 times more DOC and organic acids than maize. Consequently, lupine showed no significant alterations in enzyme activity, hotspot areas, or bacterial community composition in response to P availability. These findings demonstrate that plant-specific P deficiency adaptation mechanisms distinctly influence the spatial distribution of C-cycling enzyme activity and bacterial community structure in the rhizosphere.

Per- and polyfluoroalkyl substances (PFAS) are ubiquitous in consumer manufacturing, but their occurrence in stationery products and the associated exposure risk to children in educational environments remain unclear. A total of 17 PFAS (Σ17 PFAS) were quantitatively detected in 53 children's stationery from four categories with the overall detection frequency of 64.5 %. The concentrations of Σ17 PFAS ranged up to 70.9 ng/g, with a median value of 0.16 ng/g. The precursors in these products were confirmed by total oxidizable precursor assay. Exposure assessment showed that estimated maximum PFAS intake from pen grips via hand-to-mouth contact (0.57 ng/kg-bw/day) approached the tolerable daily intake for children established by the European Food Safety Authority (0.63 ng/kg-bw/day), highlighting a potential concern from the sources in educational environment. To further investigate the potential mechanism of PFAS dermal adsorption, molecular docking analysis was performed to evaluate the affinities of PFAS compounds toward 12 representative tight junction proteins in human skin. The emerging PFAS alternative, perfluorooctylphosphonic acid, demonstrated significantly stronger binding affinity (p < 0.05) to these tight junction proteins compared to the other analytes. This work preliminarily indicates that childhood exposure to PFAS in educational environments may occur through the use of stationery products, with computational results suggesting a potential role for tight junctions in the dermal absorption and subsequent toxicity of these compounds.

Tomato bacterial wilt caused by Ralstonia solanacearum severely limits tomato production. Although arbuscular mycorrhizal (AM) fungi and Trichoderma-enriched bio-organic fertilizer (BOF) are promising biocontrol approaches, their combined effects on plant defense and rhizosphere microbiome assembly remain unclear. A greenhouse pot experiment was conducted to evaluate tomato responses to R. solanacearum under AM fungal inoculation, T. guizhouense-enriched BOF application, and their combined treatment. Plant growth, disease severity, defense-related enzymes, phytohormones, malondialdehyde (MDA), pathogen abundance, and rhizosphere bacterial communities were analyzed using physiological assays, qPCR, and high-throughput sequencing. AM fungi and BOF reduced bacterial wilt severity and alleviated pathogen-induced growth inhibition, with the combined treatment showing the strongest suppression. Dual application reduced R. solanacearum fliC gene abundance by 0.52, 1.14, and 3.94 log copies g−1 dry soil at 1, 7, and 15 days after pathogen inoculation, respectively. Pathogen infection increased peroxidase (POD) and polyphenol (PPO) oxidase activities, salicylic acid and jasmonic acid levels, and MDA content, indicating defense activation accompanied by oxidative damage. AM fungi and BOF further enhanced defense-related responses, especially jasmonic acid accumulation and POD/PPO activities, while reducing MDA accumulation. R. solanacearum altered rhizobacterial diversity, community composition, and network structure, whereas AM fungi and BOF partially restored bacterial diversity, increased network complexity, and enriched potentially beneficial genera, including Lysobacter, Pseudoxanthomonas, Sphingomonas, and Burkholderia. PICRUSt2 predictions suggested associations with antibiotic biosynthesis- and signaling-related pathways. Overall, AM fungi combined with T. guizhouense-enriched BOF provided additive biocontrol benefits by enhancing tomato defense and restructuring rhizosphere bacterial communities, although field validation and independent repeated trials are still needed.

Soil acidification driven by human activities has emerged as a key factor aggravating plant root diseases; however, the underlying interaction-based pathogenic mechanisms remain unclear. Here, using the economically and ecologically important gymnosperm Torreya grandis as a model, we integrated multi-omics analyses of rhizosphere biota with soil physicochemical profiling to identify factors associated with root rot. We found that cross-kingdom interactions under soil acidification, rather than pathogen abundance alone, contribute substantially to disease aggravation. Soil acidification induced structural imbalances in the rhizosphere biota, characterized by a cross-kingdom interaction network comprising pathogenic Fusarium, fungal Lectera, bacterial Acidothermus, and phytophagous Hemipyxis. Synthetic community experiments further confirmed that the multi-organism interaction system formed by these biotic factors disrupted plant-soil defense functions, and thereby aggravated the severity of root rot. Collectively, these findings reveal that acidification-conditioned cross-kingdom interactions can substantially aggravate root rot, providing insights for managing soil-borne diseases and restoring degraded agroforestry ecosystems.

Nanoplastics (NPs) pose greater soil ecological risks than microplastics due to their surface charge-dependent uptake, transport, and accumulation in plants. However, how differently charged NPs affect maize growth and microbial functional resistance in rhizosphere hotspots remains unclear. Here, we investigated the effect of positively (PS-NH2) and negatively (PS-SO3H) charged NPs on maize growth, enzyme activities and gene abundance, microbial resistance, and functional properties in acidic soil using soil zymography, 16S rRNA sequencing, and metagenomics. PS-NH2 showed stronger inhibitory effects on maize growth than PS-SO3H, mainly through reducing microbial diversity and weakening N and P cycling-related enzyme activities and resistance. Conversely, PS-SO3H maintained higher microbial resistance. Functional hotspots microbial species (particularly in Actinobacteria) alleviated NPs toxicity by accelerating N and P cycling to meet the demand for nutrients limiting maize growth. This study provides a mechanistic basis for assessing soil NPs risk with implications for agricultural sustainability and food safety.

Living roots and their associated mycorrhizal fungi are critical drivers of litter decomposition and nutrient cycling. However, it remains unclear how intensive management practices (e.g., fertilization, tillage and clearing understory vegetation) alter the relative contributions of these biotic agents and their underlying regulatory mechanisms. Using an in-situ compartmented microcosm experiment in Moso bamboo (Phyllostachys edulis) plantations, we investigated how root and mycorrhizal exclusion affects litter decomposition, soil microbial assembly, and enzymatic activity under extensive and intensive management. The results showed that intensive management significantly accelerated litter decomposition but fundamentally altered its biotic drivers: the primary contribution shifted from mycorrhizal fungi (under extensive management) to living roots (under intensive management). While intensive management increased soil available nitrogen (N) and phosphorus (P), it markedly simplified microbial co-occurrence networks and shifted community assembly from stochastic processes (dispersal limitation) to deterministic processes (heterogeneous selection). Partial least squares path modeling revealed a distinct regulatory switch: under extensive management, decomposition was dominated by N- and P-acquiring enzyme activities (nutrient mining) within the mycorrhizal pathway. In contrast, intensive management decoupled the enzyme-decomposition link, with decomposition rates regulated by microbial community assembly and network complexity. These findings suggest that intensive management diminishes the ecosystem's reliance on mycorrhizal-mediated enzymatic nutrient acquisition, shifting control toward root-selected microbial communities. This study provides new insights into how management intensification rewires the biotic pathways of carbon turnover in plantation ecosystems.

Optimizing nitrogen (N) management is essential for sustaining rice productivity and improving soil N retention in paddy ecosystems, yet whether long-term fertilizer postponing (FP) regulates bacterial community assembly and microbial N-cycling potential in a compartment-dependent manner remains unclear. Using soils from an 11-year field experiment, we investigated bacterial communities and eight N-cycling genes in bulk and rhizosphere soils across three rice growth stages. Compared with conventional fertilization (CF), FP significantly increased grain yield, plant N accumulation, soil NH4 +-N (8.1%), microbial biomass N (MBN, 4.3%), and urease activity (30.3%). N-cycling genes showed pronounced temporal variation, generally peaking at the heading stage. FP increased the abundance of genes involved in N fixation, nitrification, and denitrification in bulk soil but reduced most N-cycling genes in the rhizosphere. Although bacterial alpha-diversity was unchanged, FP significantly altered bacterial community composition. Network and redundancy analysis further showed that bacterial community assembly and N-cycling potential were closely associated with soil C and N status. These findings indicate that long-term FP improves rice productivity by enhancing soil N availability and reshaping bacterial community assembly and microbial N-cycling potential in a compartment-dependent manner, providing new insights into the microbial mechanisms underlying sustainable N management in paddy soils.

Heterodera avenae (cereal cyst nematode, CCN) infects wheat and causes severe yield losses. CCN infestations can be decreased by applying phosphate fertilizer in wheat fields, but the underlying mechanisms are still largely unclear. In this study, the relationships among CCN, wheat root morphological traits, soil P fractions, and soil phosphatase activity in the rhizosphere were investigated with single superphosphate (SSP), monoammonium phosphate (MAP), diammonium phosphate (DAP), and ammonium polyphosphate (APP) application and without phosphate fertilizer (CK) application. APP most effectively inhibited the occurrence of CCN, with the number of cysts decreasing by 48.8

Understanding the assembly processes of soil microbial communities as secondary succession proceeds offers a critical insight into ecosystem recovery after disturbance. However, a comprehensive understanding of which ecological processes govern the assembly remains elusive. In this study, soil samples were sampled across four seasons (i.e., spring, summer, autumn, and winter) from various forest succession including shrubland, secondary forest, and primary forest, within a karst region in southwestern of China. The assembly of microbial communities was analyzed using the method of the null model, coupled with measurements of environmental variability. The results demonstrate that soil bacterial assembly is primarily dominated by the deterministic processes with their relative influence increases as karst forest proceeds; while soil fungal assembly is dominated by the stochastic processes, and the relative significance of stochasticity peaks in the secondary forest. Moreover, both soil bacterial and fungal communities' co-occurrence networks intensifies as forest succession. The shift in the balance between deterministic and stochastic across successional stages is predicted by factors such as plant DBH and soil nutrient availability. Specially, soil nitrate nitrogen (NO3 --N), along with plant diameter at breast height (DBH), available potassium (AK), available phosphorus (AP), and total phosphorus (TP), emerged as crucial determinants of soil microbial assembly as karst forest succeeds. Overall, our study provides the evidence that the bacterial and fungal communities' assembly vary within and across forest succession, and highlights the importance of plant properties and soil micro-environment for these community assembly in karst soil.

Gaseous carbonyl compounds serve as crucial precursors and intermediates in atmospheric photochemical reactions, significantly contributing to ambient ozone formation. To determine whether the impact of carbonyl compounds on regional ozone pollution is driven by their abundance or by specific secondary chemical processes, simultaneous field observations and observation-based modeling of ambient carbonyls were conducted at nine sites within the Chengdu Plain Urban Agglomeration (CPUA), China, during 4–18 August 2019, when three episodes of regional heavy ozone pollution occurred across eight cities within CPUA. Throughout the study, the total mixing ratios of 15 carbonyls ranged from 10.7 ± 4.2 to 35.2 ± 13.4 ppbv. The spatial distribution reveals that regions with higher concentrations of carbonyl compounds, such as around Chengdu, are also areas with more severe ozone pollution. Both the abundance and the chemical reactivity of carbonyl compounds, especially formaldehyde and acetaldehyde, play crucial roles in ozone formation in the CPUA. On ozone pollution days, carbonyl concentrations significantly increased by 22.8 % to 66.2 %. While the abundance of carbonyls is an important factor, their significant role in heavy ozone pollution within the CPUA is primarily driven by secondary chemical processes, particularly those involving alkenes and biogenic volatile organic compounds (BVOCs). Sites with higher average ozone concentrations during observations were mainly in the VOC-limited regime, while others were in the transitional regime. Additionally, the mutual transport of carbonyl compounds between cities in the CPUA suggests that regional collaboration is essential to address ozone pollution effectively. These findings offer valuable insights for developing effective strategies to control regional ozone pollution.

In the original publication [...].

We investigated the effects of bamboo invasion on the quantity and quality of litter input,soil carbon(C)and nitrogen(N)fractions and enzyme activities across an invasion sequence composed of evergreen broad-leaved forest,mixed broadleaved and bamboo forest,and pure Moso bamboo forest.The results showed that stan-ding litter biomass,annual litter production,and the litter C content in mixed broadleaved and Moso bamboo forest was lower than the broadleaved forest by 49.0％,7.3％and 8.2％,respectively,while that in pure Moso bamboo forest was lower than the broadleaved forest by 59.5％,48.6％,and 18.7％.Bamboo invasion resulted in a signifi-cant decrease in soil organic C in broadleaved forest.Compared with broadleaved forest,soil organic C and total N in pure Moso bamboo forest were decreased by 52.1％and 15.0％.There was no significant difference between the mixed forest and broadleaved forest.Bamboo invasion significantly increased soil microbial biomass C and N,but decreased soil labile and recalcitrant C pools,as well as the proportion of recalcitrant C pool to soil organic C.The activities of soil phenol oxidase,peroxidase and β-glucosidase in mixed forest and pure bamboo forest were generally lower than those in broadleaved forest.The specific enzyme activities(per unit of soil organic C)in bamboo forest was significantly higher than that in the broadleaved forest and mixed forest.Soil organic C content and the recalci-trant C fraction were significantly positively correlated with annual litter production,standing litter biomass,and lit-ter C content,but negatively correlated with the specific enzyme activities of phenol oxidase and peroxidase.Results of structural equation modeling showed that Moso bamboo invasion decreased recalcitrant C pool mainly by reducing litter input and enhancing the specific activities of enzymes involved in organic C degradation.In conclusion,Moso bamboo invasion reduced litter C input,increased the specific activities of soil enzymes involved in soil organic mat-ter decomposition,which was not conducive to the accumulation of soil organic matter in broadleaved forest.

ABSTRACTBiochar amendments in rice‐wheat systems are sustainable for reducing GHGs (greenhouse gases) and improving soil health but the widespread adoption of biochar faces economic challenges. To address limitation, a novel biochar‐based urea was formulated for environmental and cost advantages. A pot experiment within a rice‐wheat rotation was conducted to evaluate comparative effects of biochar‐based urea (CKBU), biochar + urea (BCU), and biochar‐based urea + biochar (BCBU) over conventional mineral fertilizer (CKU) on soil ammonia (NH3) volatilization, GHG emissions, soil structure, and crop productivity. Furthermore, fertilizer N fate was tracked using the 15N isotope during wheat season. The results indicated that compared to CKU, CKBU, BCU, and BCBU treatments significantly mitigated NH3 volatilization by 22%–31% during the rice season, and a 19% reduction was observed under the BCBU treatment during the wheat season due to the response of N‐cycling microorganisms. Regarding GHG emissions, the CKBU, BCU, and BCBU treatments significantly decreased the global warming potential (GWP) value by 49%–55% during the rice season and by 26%–45% during the wheat season, compared to CKU. Additionally, CKBU enhanced 15N use efficiency by 29% during wheat season, without affecting the rice season. The economic performance indicated that applying BU alone offered a net economic benefit, whereas biochar amendment led to a net economic loss. However, biochar amendment improved SOC and aggregation structure, with a significant increase in macroaggregate distribution over 50% compared to CKU and CKBU. Therefore, BU with small portions of biochar can be as effective in reducing NH3 emissions and mitigating GHG emissions as the use of a large quantity of biochar. Additionally, the BCBU did not show additional synergistic benefits regarding emission reduction or yield enhancement. Therefore, shifting biochar to BU could be a cost‐effective approach to achieving sustainable productivity in rice‐wheat crop rotation systems.