Plant and Soil

Ren, Suxian; Wang, Dianjie; Huo, Tianci; Yang, Hao; Liang, Junyi

doi: 10.1007/s11104-026-08477-9pmid: N/A

Background and aimsPlant belowground biomass (BGB) is critical for ecosystem functions but remains understudied compared to aboveground biomass (AGB). Nitrogen (N) enrichment is known to impact BGB, yet the underlying mechanisms are poorly understood. Methods.We conducted a multi-level N enrichment experiment that manipulates forms and quantity of N in a temperate grassland by adding three chemical forms of N (Ca(NO3)2, NH4NO3, and (NH4)2SO4) with six levels (0, 4, 8, 16, 24, 32 g N m−2 year−1) in 2021–2023. Plant biomass, light asymmetry, soil inorganic N, pH, and exchangeable metal ions were measured to reveal the mechanisms of BGB responses to inorganic N enrichment.ResultsPlant BGB initially increased at low N rates but declined with further enrichment, forming an unimodal response. The threshold of plant BGB occurred at 16.0, 21.1, and 24.4 g N m−2 year−1 for (NH4)2SO4, NH4NO3, and Ca(NO3)2, respectively. Below the threshold, increases in soil available N and plant AGB promoted BGB accumulation. Beyond the threshold, oxidized N (NO3−) mainly suppressed BGB by enhancing soil available N and intensifying light competition, whereas reduced N (NH4+) exerted stronger negative effects by additionally inducing soil acidification, ammonium toxicity, and metal toxicity.ConclusionOur results demonstrate that the threshold of BGB response to N enrichment is dually regulated by biomass allocation – which could be induced by both oxidized and reduced N, as well as cation toxicity – which is more related to reduced N. These findings highlight that the dual mechanisms determing the BGB response to N enrinshment are N-form-dependent.

Vallicrosa, Helena; Mariotte, Pierre; Hagedorn, Frank; Fuchslueger, Lucia; Martins, Nathielly; Milano, Arianna; Grossiord, Charlotte

doi: 10.1007/s11104-026-08471-1pmid: N/A

Background and aimsClimate change is expected to intensify drought and heatwaves, with major consequences for nutrient cycling in grasslands. Plant-soil-microbe interactions regulate nitrogen (N) dynamics, yet their responses to simultaneous warming and drought remain unclear, especially across plant species and land management histories.MethodsWe conducted a factorial warming and drought manipulation on six temperate grassland species belonging to three functional groups (grasses, forbs, legumes) grown in soils from intensively (Int) and extensively (Ext) managed grasslands. We quantified N content and biomass production across soil, microbes, roots, and shoots. We inferred fungi:bacteria by microbial C:N, not by direct soil community determination. Results Under control and warming conditions, Int soils supported up to 50% higher plant biomass than Ext soils, but this advantage disappeared under drought, reducing plant biomass by ~ 40%. Warming consistently reduced microbial biomass by up to 30% in both soil types. In contrast, drought decreased microbial biomass in Int soils but increased it by ~ 20% in Ext soils, likely reflecting their more drought-resistant fungal communities. These changes altered N flows: extractable soil N was up to three times higher in Int soils under warming and drought, indicating greater vulnerability to N losses, whereas Ext soils maintained low extractable soil N except under combined stress.ConclusionsIntensive management boosts plant biomass under mild and warm conditions but increases susceptibility to N loss during climate extremes. Extensive management supports more stable biomass and N cycling. Integrating microbial dynamics and land-use history is essential for predicting grassland resilience and improving N cycling models under global change.

Singhal, Vikas Kumar; Ghosh, Avijit; Singh, Amit K.; Bhattcahryya, Ranjan; Singh, Yogeshwar; Kumar, Sourav; Ojha, Deepak; Shukla, Arun K.

doi: 10.1007/s11104-026-08423-9pmid: N/A

AimThe temperature sensitivity of labile (Q10L) and recalcitrant (Q10R) pools of soil organic carbon (SOC) decomposition is a critical for predicting soil carbon (C) fluxes.MethodsSoils under six grass covers, namely, Cenchrus ciliaris, Chrysopogon fulvus, Panicum maximum, Sehima nervosa, Heteropogon contortus, and Vetiveria zizanioides from semi-arid India were evaluated for Q10L and Q10R of bulk soil, macroaggregates, microaggregates, and silt + clay associated SOC. Soil fractions (from 0–20 and 21–40 cm depths) were incubated at 25, 32, and 37 °C for 100 days, and cumulative C mineralization was measured. The Q10L and Q10R were calculated using a two-pool decay model. The quality of root litter C and SOC was assessed through FTIR spectroscopy.ResultsQ10L and Q10R of microaggregate-C was significantly higher (22–64% and 22–24%, respectively) than macroaggregate-C and silt + clay-C. Among grasses, Q10L and Q10R values under C.ciliaris, H.contortus, and S. nervosa were lower (by 6–35%) than other grasses, indicating their capability to store SOC under global warming scenarios. Q10L at topsoil layer was correlated with root litter C quality (r = -0.641 to 0.633) and at the sub-surface soil layer, it was influenced by labile C concentration (r > 0.637). The Q10R was correlated with the recalcitrant C concentration (r > 0.721) and SOC quality in both soil layers, indicating that quality and availability of recalcitrant SOC had pivotal roles in governing Q10R in restored land.ConclusionsSoil C and litter C quality should be potentially incorporated into the biogeochemical models to better predict SOC dynamics in managed ecosystems in the context of global warming and land use changes.

Gao, Junmei; Ni, Lingshan; Liu, Chen; Wang, Xiaoli; Li, Shixiong; Fang, Nufang; Liu, Yu

doi: 10.1007/s11104-026-08333-wpmid: N/A

AimsSoil erosion resistance, a critical indicator for regional erosion risk assessment and soil loss prediction, is essential for maintaining agricultural ecosystem sustainability in alpine regions. Vegetation restoration mitigates erosion, but the temporal dynamics of restoration and its driving mechanisms on erosion resistance remain poorly quantified.MethodsWe investigated soil physical properties, root morphological traits, and the Comprehensive Soil Erosion Resistance Index (CSERI) in sown grasslands (Poa pratensis) across a chronosequence of stand ages (1, 2, 7, 8, and 12 years).ResultsOur results revealed that root architectural traits and soil physical parameters exhibited nonlinear responses to stand age, with synergistic interactions enhancing erosion resistance and ecosystem resilience. Soil properties exerted stronger direct effects than root traits on CSERI which dominated by soil physical conditions rather than root architecture. Crucially, erosion resistance followed a stage-dependent trajectory, peaking at 7–8 years due to optimal root-soil feedbacks.ConclusionsA multilevel control structure emerged, with clay content as the dominant factor, bulk density as a mediator, and root traits exerting indirect effects. These findings provide mechanistic insights for optimizing erosion control strategies and timing adaptive management in alpine grasslands, supporting sustainable agroecosystem resilience in erosion-prone environments.

Pollet, Sasha; Cornelis, Jean-Thomas; Knipfer, Thorsten; Prescott, Cindy; Tate, Kylee; Kim, Young-Mo; Lobet, Guillaume

doi: 10.1007/s11104-026-08356-3pmid: N/A

AimsHarnessing rhizosphere processes offers a valuable opportunity to optimize nutrient use efficiency in agroecosystems. In nutrient-limited soils, plants discharge part of photosynthate surplus via root exudation, including carboxylates, which may enhance mineral dissolution and nutrient mobilization. We aimed to assess how plant responses to phosphorus supply translated into changes in exudate profiles, and how these exudates, in turn, drive mineral dissolution across soil horizons of contrasting mineralogy and weathering degree.MethodsWe conducted a hydroponic experiment with Lupinus albus grown in a phosphorus (P) gradient over seven weeks. We measured plant biomass and root traits, performed a metabolomics analysis and quantified seven carboxylates in root exudates using gas chromatography-mass spectrometry. To assess mineral dissolution across contrasted soil development stages, we conducted batch dissolution tests with exudates using three soil horizons—each with distinct physicochemical properties: enriched in organic matter, iron oxides, or primary silicates.ResultsAt the intermediate level of P supply, shoot biomass was comparable to that under high P, but plants produced more root biomass and a higher carboxylate exudation rate. Despite low carboxylate concentrations (< 100 ppb), exudates promoted the dissolution of Ca, Mg, Si, Fe and P in all soils. Yet, the degree of element released varied among soil horizons.ConclusionThese findings highlight the importance of root exudates in enhancing mineral dissolution, with effects dependent on soil physicochemical properties. The results suggest that managing agroecosystems under moderate nutrient limitation could be a sustainable strategy to increase root-to-shoot ratios, enhance dissolution and nutrient release in rhizosphere.

Li, Jiaxue; Wang, Meng; Yang, Wenbo; Shen, Congying; Zhang, Lei; Li, Qian; Sun, Bo; Qin, Yubo; Li, Cuilan; Zhang, Jinjing; Liu, Hang

doi: 10.1007/s11104-026-08480-0pmid: N/A

Background and aimsTraditionally, ammonia oxidation has been attributed to ammonia-oxidizing bacteria (AOB) and archaea (AOA). However, complete ammonia-oxidizing bacteria (Comammox) can perform nitrification in its entirity, transforming current understanding of microbial N cycling and necessitating further investigation. Here, the influence of different maize-soybean rotation systems on AOA, AOB, and Comammox community composition and abundance were examined in farmland soils under drip fertigation in semi-arid regions of Northeastern China.MethodsExperimental treatments included soybean continuous cropping (SC) and three rotations: maize-soybean (MS), maize-maize-soybean (MMS), and maize-soybean-soybean (MSS). Quantitative fluorescence PCR and high-throughput sequencing were employed to assess microbial abundance and community structures.ResultsThe present findings revealed that, soybean rotation enhanced hydroxylamine oxidase (HAO) and ammonia monooxygenase (AMO) activities, as well as soil nitrification potential (PNR). Among the rotation treatments, MMS and MSS exhibited significantly higher PNR and enzymatic activities than MS. AOA and AOB were significantly more abundant in rotation systems than in SC. However, in contrast, Comammox levels were markedly lower in rotation treatments. Community structure analysis revealed significant variation in AOA, AOB, and Comammox between rotation systems and SC, with organic matter (SOM), alkali hydrolyzed nitrogen (AN), and ammonium nitrogen (NH4+-N) found to drive these shifts. Structural changes in AOA, AOB, and Comammox community compositions were found to directly influence PNR. Notably, relative Comammox contributions to nitrification surpassed that of conventional ammonia oxidizers.ConclusionsIn conclusion, these results suggest that Comammox contributed predominantly to ammonia oxidation in soybean continuous cropping and rotation systems under drip fertigation.Graphical Abstract[graphic not available: see fulltext]

Wang, Jiaojiao; Zang, Fei; Wang, Ruochun; Wei, Shujing; Zeng, Wenfang; Hao, Hu; Zhao, Chuanyan

doi: 10.1007/s11104-026-08450-6pmid: N/A

Background and aimsLitter decomposition is a critical process in grassland biogeochemical cycles. However, the synergistic mechanisms by which climate warming regulates it remain poorly understood, particularly regarding the role of trace elements.MethodsWe simulated climate warming in the Qilian Mountains using open-top chambers (OTCs), with a warming magnitude of 0.42℃ for Agropyron cristatum (A. cristatum) and 0.74℃ for Achnatherum splendens (A. splendens), two dominant species in the Qilian Mountains grassland. Integrative analyses of litter quality, soil enzyme activities, microbial diversity, and trace element dynamics were performed to clarify the regulatory mechanisms of warming on litter decomposition.ResultsOur findings revealed a species-specific response. Warming significantly suppressed the decomposition rate of A. splendens litter by 11.9%, while showing no effect on A. cristatum. The inhibition of A. splendens decomposition was linked to an elevated litter N:P ratio and reduced fungal diversity under warming. Importantly, warming decreased the dynamics of trace elements in the A. splendens litter-soil system. Structural equation modeling revealed that warming directly regulated litter quality and indirectly modified the microbe-enzyme-trace element interaction network, thereby controlling litter decomposition rates.ConclusionsThis study reveals that subalpine grassland litter decomposition exhibits distinct, species-specific responses to experimental warming. It highlights the pivotal role of trace elements in mediating microbial and enzymatic processes in the response of litter decomposition to warming. These findings are vital for predicting the impact of climate change on nutrient cycling in grassland ecosystems.

Liu, Wenbin; Chen, Xiaoting; Yang, Wenyan; Dong, Dubin; Xu, Youxiang; Ye, Zhengqian; Liu, Dan; Wang, Mei; Ma, Jiawei

doi: 10.1007/s11104-026-08436-4pmid: N/A

PurposeBio-organic fertilizers derived from beneficial microbial strains offer an effective strategy to reduce chemical fertilizer use in tea cultivation. This study investigated the effects of three novel bio-organic fertilizers on soil quality and tea biochemical composition in tea plantations.MethodsA three-year field experiment was conducted with five treatments: an unfertilized control (CK), conventional chemical fertilizer (CF), and three bio-organic fertilizers containing Bacillus megaterium (BMG), B. mucilaginosus (BMU), or B. subtilis (BCL). Soil microbial diversity and community composition were analyzed using high-throughput Illumina sequencing. These microbial profiles were integrated with soil physicochemical properties, enzymatic activities, and tea leaf metabolites—including amino acids and secondary compounds—through a multi-omics approach.ResultsAll bio-organic fertilizers significantly increased soil organic matter content, microbial diversity, and co-occurrence network complexity. BMG and BCL treatments promoted Acidobacteriota abundance, while BMU enhanced Actinobacteriota and Chloroflexi dominance. Metabolomic analysis showed that BMG treatment notably increased the biosynthesis of key amino acids (e.g., aspartate, phenylalanine) and flavonoids (e.g., quercetin, luteolin). Correlation analysis revealed strong associations between microbial shifts and metabolite accumulation driving tea quality. Moreover, BMG significantly elevated total amino acid and flavonoid contents and lowered the phenol-to-amino acid ratio, contributing to improved tea quality.ConclusionsThe bio-organic fertilizer containing B. megaterium substantially enhanced tea quality by selectively promoting key amino acid and flavonoid biosynthesis. These findings demonstrate the potential of microbial-based biofertilizers to improve tea cultivation and provide insights for their optimized design.Graphical abstract[graphic not available: see fulltext]