Geoderma最新文献

{"title":"Lithology and bioclimate impacts on soil organic phosphorus speciation and the relationship between phosphatase and organic phosphorus in California temperate forest","authors":"Suwei Xu ,&nbsp;Chunhao Gu ,&nbsp;Stewart G. Wilson ,&nbsp;Rota Wagai ,&nbsp;Yuhei Nakayama ,&nbsp;Andrew J. Margenot","doi":"10.1016/j.geoderma.2025.117314","DOIUrl":"10.1016/j.geoderma.2025.117314","url":null,"abstract":"<div><div>The dynamic equilibrium between soil phosphatase activities and soil organic phosphorus (P_o) species can be impacted by soil forming factors. While much research has addressed soil P_o dynamics as a function of time using chronosequences, understanding of lithology and bioclimate impacts on soil P cycling remains comparatively limited. We tested hypothesized interactive impacts of lithology and bioclimate on the quantity and quality of soil P_o, and relationships between P_o composition and phosphatase activities using a full factorial combination of three lithologies (andesite, basalt, granite) and four bioclimatic zones (blue oak, ponderosa pine, white fir, red fir) constrained by elevation ranges across the Sierra Nevada and southern Cascades in California, USA. Activities of acid and alkaline phosphomonoesterase (PME) and phosphodiesterase (PDE) were positively associated with concentrations of P_o species determined by NaOH-EDTA extraction and solution ³¹P nuclear magnetic resonance (NMR) spectroscopy. Concentrations of P_i and P_o species and species class (i.e., phosphomonoesters, phosphodiesters) were positively related to PME activities, whereas PDE activity was correlated to P species concentrations at species class level of phosphodiesters. Soil inositol hexakisphosphate (IHP) and most non-IHP monoesters (e.g., glucose-6′ phosphate, α- and β-glycerophosphate, phosphocholine), phosphodiesters (i.e., deoxyribonucleic acid), and inorganic phosphates (i.e., (pyro)phosphate) were 68–232 % higher in soils developed on andesite (monoester 312 mg kg⁻¹; diester 25 mg kg⁻¹), followed by basalt (monoester 174 mg kg⁻¹; diester 20 mg kg⁻¹), and lowest in granite (monoester 133 mg kg⁻¹; diester 12 mg kg⁻¹), reflecting greater contents of poorly crystalline Fe/Al oxides and P from intermediate parent materials. Bioclimatic impacts on concentrations and proportions of P_o species were highly specific to lithology, with P species concentrations lowest at the highest elevation (red fir) for andesite- (monoester 265 mg kg⁻¹) and basalt-derived soils (monoester 67 mg kg⁻¹), whereas P concentrations in granite-derived soil (monoester 108–183 mg kg⁻¹) were largely uninfluenced by bioclimate. Relationships among phosphatase activities and P_o species concentrations were mainly observed in mafic material-derived soils, and were highly specific to P species at a given bioclimate. Integrating lithology and bioclimate context may enable more comprehensive assessments of soil P cycling.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117314"},"PeriodicalIF":5.6,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143943481","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Deep learning segmentation of soil constituents in 3D X-ray CT images","authors":"Maxime Phalempin ,&nbsp;Lars Krämer ,&nbsp;Maik Geers-Lucas ,&nbsp;Fabian Isensee ,&nbsp;Steffen Schlüter","doi":"10.1016/j.geoderma.2025.117321","DOIUrl":"10.1016/j.geoderma.2025.117321","url":null,"abstract":"<div><div>Accurate segmentation of soil constituents in X-ray CT imagery is critical for advancing our understanding of soil structure dynamics. However, difficulties arise because of the overlapping X-ray attenuation of soil constituents, which makes segmentation based on voxel intensity alone impossible. In this study, we explore the potential of nnUNet, a deep learning-based semantic segmentation model, for applications in soil science. We evaluated nnUNet on three challenging datasets: (1) complex soil structure with numerous material classes with overlapping gray value ranges, (2) fine roots in noisy images, and (3) permafrost with gradual gray value transitions between sediment types. The performance of nnUNet was compared to other reference methods, namely Ilastik, Rootine v.2, and manual thresholding. The Dice scores indicated overall good model performance across all three datasets. Compared to the reference methods, nnUNet outperformed Ilastik on Dataset 1. For Dataset 2, nnUNet produced segmentations with fewer false-positive roots than Rootine v2; however, this came at the expense of missing fine roots that were barely visible to the naked eye and, therefore, not annotated. In Dataset 3, we encountered challenges in annotating classes due to gradual transitions in voxel intensity. Our study underscores that deep learning models like nnUNet perform well for the segmentation of complex soil structures and could assist the development of a generalized segmentation model, thereby fostering standardization in soil structure analysis. To achieve this, increased access to diverse and well-curated annotations is still necessary.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117321"},"PeriodicalIF":5.6,"publicationDate":"2025-05-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143934826","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Magnitudes, patterns, controls and mitigation potentials of net ecosystem carbon balances across wetlands in China","authors":"Lei Ma ,&nbsp;Dezhao Gan ,&nbsp;Zheng Li ,&nbsp;Dongyou Wu ,&nbsp;Wei Pu ,&nbsp;Xiangyue Chen ,&nbsp;Gaofeng Zhu ,&nbsp;Shuli Niu ,&nbsp;Jinsong Wang ,&nbsp;Ruijun Long ,&nbsp;Hongchao Zuo","doi":"10.1016/j.geoderma.2025.117332","DOIUrl":"10.1016/j.geoderma.2025.117332","url":null,"abstract":"<div><div>China contains Asia’s largest wetlands, which include diverse wetland types, e.g., peatlands, marshes and mangroves; these wetlands are found from inland to coastal regions. Over the past four decades, considerable amounts of natural wetlands have been drained, thus severely decreasing their carbon (C) sequestration ability. Recent rewetting has been initiated to restore wetland ecosystem services and mitigate carbon dioxide (CO₂) emissions. However, the magnitudes, patterns, controls and mitigation potentials of annual net ecosystem C balances (NECB) have not been adequately studied, leading to large uncertainties in predicting wetland C cycles under climate change and anthropogenic activities across different wetlands in China. These influencing factors include the combinations of vertical net ecosystem exchange of CO₂ (NEE) and horizontal C removal through biomass harvest, as well as dissolved organic and inorganic C (DOC and DIC) exports. Here, using the annual measurement of NECB from 148 sites across different wetlands in China, we found that the annual NECB varied widely from –9413 to + 8760 kg C ha⁻¹ yr⁻¹; these fluxes were collectively influenced by wetland status, wetland location, and wetland type. Drainage turned natural wetlands from net C sinks to net C sources (<em>p</em> &lt; 0.05), regardless of whether wetlands were inland or coastal, while rewetting significantly (<em>p</em> &lt; 0.05) reversed the net C loss trends from drained wetlands to net C uptake in rewetted wetlands. Coastal wetlands had significantly greater (<em>p</em> &lt; 0.05) annual C uptake than inland wetlands, with coastal mangroves exhibiting the highest uptake rates. Eighty percent of the spatial variations in the annual NECB were explained (<em>p</em> &lt; 0.0001) by the spatial variations in the mean annual temperature (MAT) and water table depth (WTD) across different wetlands in China. Scenario analysis showed that drained wetlands should be rewetted promptly; postponing rewetting causes larger emissions from continued C losses from drained wetlands.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117332"},"PeriodicalIF":5.6,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143934824","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Reconciling historic and contemporary sampling of soil organic carbon stocks: Does sampling approach create systematic bias?","authors":"Sam McNally ,&nbsp;Jack Pronger ,&nbsp;Jordan Goodrich ,&nbsp;Kara Allen ,&nbsp;Scott Graham ,&nbsp;Stephen McNeill ,&nbsp;Pierre Roudier ,&nbsp;Tim Norris ,&nbsp;Alice Barnett ,&nbsp;Louis Schipper ,&nbsp;Paul Mudge","doi":"10.1016/j.geoderma.2025.117338","DOIUrl":"10.1016/j.geoderma.2025.117338","url":null,"abstract":"<div><div>Accurate determination of soil organic carbon stocks is important to track long-term change due to land management or land use, for greenhouse gas (GHG) inventory reporting, and carbon trading associated with these changes. Typically, these stock measurements are carried out, using either horizon-based or continuous core sampling, to collect soil bulk density, organic carbon content and depth of the desired layer. Differences in methods also relate to the soil organic carbon (SOC) collection via a core or a horizon scraping. There is also growing consensus that stocks should be calculated on an equivalent soil mass basis to reduce error in measurements and account for biases related to changes in bulk density. Here we quantify SOC stocks measured using four different field sampling methods (variations of depth-based and horizon-based sampling using pits, or continuous core sampling). We then compare the results using either: i) a fixed-depth; or ii) an equivalent soil mass calculation (ESM) approach. Our results demonstrate that there was no bias associated with depth-based or horizon-based methods, where bulk density was determined in the centre of each layer, and carbon content across the full horizon, compared to a core sampling method where both bulk density and SOC content were determined continuously for the whole profile in fixed-depth increments. While there are small differences between methods when fixed depth sampling was used, these differences can be substantially reduced when using ESM. Reprocessing of SOC stock data using ESM should be carried out to reconcile any potential differences caused between sampling methods in historic and contemporary datasets.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117338"},"PeriodicalIF":5.6,"publicationDate":"2025-05-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143934825","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Ecosystem-level warming reduces microbial necromass in the topsoil but not in deeper soil of a subtropical forest","authors":"Xujun Liu ,&nbsp;Peter B. Reich ,&nbsp;Chao Liang ,&nbsp;Meijuan Xiao ,&nbsp;Gangsheng Wang ,&nbsp;Guoyi Zhou ,&nbsp;Kristiina Karhu ,&nbsp;Zhiyang Lie ,&nbsp;Ting Wu ,&nbsp;Shuyidan Zhou ,&nbsp;Zuzheng Li ,&nbsp;Junhua Yan ,&nbsp;Xuli Tang ,&nbsp;Guowei Chu ,&nbsp;Shizhong Liu ,&nbsp;Ze Meng ,&nbsp;PingPing Xu ,&nbsp;Qianmei Zhang ,&nbsp;Zhanfeng Liu ,&nbsp;Juxiu Liu","doi":"10.1016/j.geoderma.2025.117336","DOIUrl":"10.1016/j.geoderma.2025.117336","url":null,"abstract":"<div><div>Rising temperatures in subtropical regions pose a significant challenge to soil carbon (C) storage. Microbial necromass is an important contributor to the persistent soil C pool, yet little is known about its responses to warming in subtropical forest ecosystems. Here, we executed an 8-year continuous sampling campaign in a subtropical forest ecosystem-level passive warming experiment (+0 °C, +1.0 °C and +2.1 °C). We observed a decline in soil microbial necromass C under higher temperatures. +2 °C warming significantly reduced the topsoil (0–10 cm) microbial necromass C by 23 %, partially due to the decreased soil nitrogen caused by the elevated nitrogen requirements of plant growth, as well as the soil drying and decrease in microbial biomass. However, we found that the subsoil (10–40 cm) microbial necromass C was unchanged under warming. Random forest analysis and structural equation models suggested that this attenuated effect with soil depth was primarily attributed to the enhanced mineral protection in deeper soil and more stable microbial composition in deeper soil. The depth-dependent temperature response of microbial necromass should be considered in Earth system models to obtain accurate predictions of climate change impacts on subtropical forests.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117336"},"PeriodicalIF":5.6,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143931842","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Cropping system is a key determinant of soil health after accounting for environmental and edaphic variability","authors":"Franky Celestin ,&nbsp;Gabriel Maltais-Landry ,&nbsp;Jose C.B. Dubeux ,&nbsp;Rao S. Mylavarapu ,&nbsp;Yang Lin","doi":"10.1016/j.geoderma.2025.117330","DOIUrl":"10.1016/j.geoderma.2025.117330","url":null,"abstract":"<div><div>Soil health assessment is critical for understanding and promoting sustainable soil management practices. Soil health assessment methods incorporate a variety of inherent environmental and edaphic properties, including climate variables and texture, as well as cropping system. However, these inherent properties often vary systematically among cropping systems and potentially confound the effects of cropping system on soil health. Using a new soil health dataset in Florida, we adopted propensity score weighting to model each sample’s probability of belonging to a particular cropping system based on soil drainage class, clay content, mean annual temperature (MAT), and mean annual precipitation (MAP). By balancing these factors across systems, this method enabled unbiased estimation of cropping system effects. The effects of cropping system on soil health indicators remained statistically meaningful after propensity score weighting using the same significance threshold (<em>α</em> = 0.05). Soil organic matter and carbon-related indicators were consistently higher in grazed pastures than in row crop systems, indicating that differences in disturbance and management intensity across cropping systems regulated soil health. Similarly, soil pH and phosphorus saturation ratio (PSR) were higher in row crop systems than in grazed pastures, which likely reflected the differences in chemical inputs among these systems. In contrast, our results showed that before propensity score weighting, Mehlich-3 extractable nutrients were higher in row crops than in hayfields and grazed pastures; however, these effects became non-significant after weighting, suggesting that they were partially driven by differences in inherent properties among cropping systems. Variance partition analysis further confirmed cropping system as a consistent driver of the carbon-based indicators, while the impacts of inherent properties were indicator-specific. Overall, our results demonstrate the importance of considering variability in inherent properties when evaluating cropping system impacts on soil health. Propensity score weighting offers a robust approach for addressing complex interactions among soil health drivers.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117330"},"PeriodicalIF":5.6,"publicationDate":"2025-05-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927519","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Achieving the goal of the “4‰ initiative” and agricultural sustainability by co-incorporating rice straw and Chinese milk vetch for rice production in southern China","authors":"Yu Zhang ,&nbsp;Wangwang Zhang ,&nbsp;Fei Xu ,&nbsp;Yuhang Qin ,&nbsp;Hao Chen ,&nbsp;Yuhong Wu ,&nbsp;Shuo Li","doi":"10.1016/j.geoderma.2025.117333","DOIUrl":"10.1016/j.geoderma.2025.117333","url":null,"abstract":"<div><div>The co-incorporation of rice straw (RS) and Chinese milk vetch (CMV) has been suggested as an optimized agronomic management strategy to improve soil organic carbon (SOC) storage and agricultural sustainability. This study was designed to evaluate effects of co-incorporating RS and CMV (RS-CMV) on rice grain yields, sustainable yield index (SYI), economic benefit, the sequestration and stratification of SOC, carbon fractions, and the achievement of the 4 ‰ initiative, especially under lowering 30 % N rate in southern China. Four-year field experiments were designed and implemented with four treatments: no straw incorporation as the control (CK), RS incorporation (RSI), RS-CMV, and lowering 30 % N rate based on RS-CMV (RS-CMVL). Results showed that the RS-CMV exhibited the largest annual average rice grain yields, SYI, and economic profit, higher by 6.2 ∼ 9.4 %, 6.4 ∼ 9.2 %, and 6.4 ∼ 16.8 %, respectively, than those of CK and RSI, and had no obvious discrepancy with the RS-CMVL. Throughout the 0–40 cm soil profile, the RS-CMV and RS-CMVL significanly enhanced SOC storage by 12.5 % and 12.0 % relative to the CK, by9.1 % and 8.6 % relative to the RSI, and by 10.0 % and 9.6 % relative to the pre-experimental soil (2018), respectively. The C sequestered rate per 1000 reached 25.1 ‰ year⁻¹ and 23.9 ‰ year⁻¹ under RS-CMV and RS-CMVL, while no difference existed between RS-CMVL and RS-CMV. As well, the RS-CMV led to the highest storages of soil labile organic carbon fractions (LOCs), especially the highly labile organic carbon, while the RS-CMVL sequestered the largest recalcitrant organic carbon throughout the entire 0–40 cm soil layer. The RS-CMV increased the stratification ratio of LOCs, while no obvious discrepancy was observed when evaluating the SR of SOC. What’s more, the cumulative carbon and nitrogen inputs are highly correlated with the storages of SOC and its LOCs, and the SYI. The co-incorporation of RS and CMV, even under lowering 30 % N rate, was mainly responsible for the improvements of rice grain yields, sustainable yield index, economic profit, SOC and its fractions’ storage, and therefore could enhance SOC sequestration and agricultural sustainability, effectively achieving the goal of the “4‰ initiative”.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117333"},"PeriodicalIF":5.6,"publicationDate":"2025-05-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143927518","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Synergistic effects of microbial networks, glomalin-related soil protein, and humic substances jointly enhance the stability of soil aggregates: Evidence from converting pure Pinus massoniana plantations into uneven-aged mixed forests","authors":"Haimei Huang ,&nbsp;Xueman Huang ,&nbsp;Xinyu Zhu ,&nbsp;Yi Wang ,&nbsp;JinLiu Yan ,&nbsp;Jiajun Li ,&nbsp;Angang Ming ,&nbsp;Yeming You","doi":"10.1016/j.geoderma.2025.117334","DOIUrl":"10.1016/j.geoderma.2025.117334","url":null,"abstract":"<div><div>The stability of soil aggregates (SSA) serves as a sensitive indicator of soil fertility and plays a crucial role in determining resistance to erosion. However, the synergistic mechanisms of microorganisms, glomalin-related soil protein (GRSP), and humic substances (HS) by which SSA is altered through the conversion of <em>Punus massoniana</em> monoculture plantations into mixed broadleaf-conifer plantations remain unclear. We applied three different soil aggregate analysis methods, combined with high-throughput sequencing regions, to examine the impact of plantation diversification on SSA and microbial community structure. Specifically, we investigated a mixed plantation (MP) composed of two uneven-aged tree species (<em>P. massoniana</em> and <em>Castanopsis hystrix</em>) and a multiple-species mixed plantation (MMP) composed of several uneven-aged tree species (<em>P. massoniana</em>, <em>Castanopsis hystrix</em>, <em>Michelia hedyosperma</em>, <em>Erythrophleum fordii</em>, and <em>Quercus griffithii</em>). These were compared to a pure plantation (PP) of <em>P. massoniana</em> as the control. We also analyzed HS components and GRSP contents. Our results showed that the mean weight diameter (MWD) index and the proportion of soil macroaggregates (&gt;0.25 mm) were significantly higher, while the new aggregate stability index (AS) was significantly lower in MP and MMP than in PP. Chao1 index values for bacteria (0–10 and 10–20 cm soil layers) and fungi (0–10 cm soil layer) were significantly higher in the MMP than in MP and PP. Moreover, the MP and MMP had greater HS component and GRSP levels than the PP plantations. The relative abundance of <em>Chloroflexi</em>, <em>Gemmatimonadota</em>, <em>Ascomycota</em>, and <em>Kickxellomycota</em> primary affected the particle size distribution of aggregates. PLS-PM revealed that higher litterfall mass (LF) and fine root biomass (FR) in mixed broadleaf-conifer plantations enhanced microbial diversity and network complexity via soil C and N accumulation, which directly stimulates GRSP secretion and HS formation, thereby enhancing SSA. Therefore, the introduction of broadleaf species into pure <em>P. massoniana</em> plantations is an effective strategy for preventing land degradation by preserving the complexity of belowground communities. Taken as a whole, this study provides new insights into the intricate interplay of plant–microbe-soil that will contribute to developing plantation management strategies to enhance stability of soil structure.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117334"},"PeriodicalIF":5.6,"publicationDate":"2025-05-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143917927","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-term conservation tillage breaks the plough pan and promotes the development of preferential flow","authors":"Jinze Han ,&nbsp;Jianye Li ,&nbsp;Qiang Chen ,&nbsp;Xingyi Zhang","doi":"10.1016/j.geoderma.2025.117329","DOIUrl":"10.1016/j.geoderma.2025.117329","url":null,"abstract":"<div><div>Macropores and preferential flow critically regulate soil hydrological functions and ecosystem services in agricultural systems. With the intensification of global soil degradation, especially as conventional tillage (CK) exacerbates soil compaction, conservation tillage (CT) has emerged as a crucial strategy for restoring soil quality. However, the ability of CT to alleviate soil compaction and regulate macropore structure and preferential flow remains unclear. This study aimed to clarify how long-term CT alleviates compaction-driven constraints on macropore structure and preferential flow in black soil. We selected an 18-year located experimental field on a typical Phaeozem (clay loam, mixed, mesic) in black soil region of Northeast China. X-ray computed tomography (25 μm resolution) and dye tracer techniques (1.5 g L⁻¹ Brilliant Blue solution) were used to quantify macropores and preferential flow paths in 0–50 cm soil layers. Independent samples <em>t</em>-test (assuming equal variances and normal distributions) was used to compare two treatments. Correlation analysis was also performed to assess variable relationships. Path analysis via structural equation modeling to elucidate direct and indirect effects, and CMIN/DF, GFI, RMSEA were used to evaluate model fit. The results revealed that CT effectively alleviated soil compaction by breaking the plough pan and optimizing pore structure. Compared with CK, CT significantly enhanced macroporosity (500–1000 μm) by 4.8 times and pore connectivity by 21.3 times in the critical 10–20 cm layer, while reducing bulk density by 9.4 % and pore tortuosity by 2.1 % in this layer (<em>p</em> &lt; 0.05). Notably, CT generated continuous pore and staining paths extending below 20 cm, thereby alleviating the plough pan barrier. These structural improvements drove preferential flow development, evidenced by a 21.5 % reduction in dye variation coefficient and enhanced soil dye coverage. Correlation analysis showed dye coverage correlated strongly with soil physicochemical properties and macropore indexes, especially 500–1000 μm macroporosity (<em>p</em> &lt; 0.05). Path analysis further confirmed CT governed preferential flow patterns through macroporosity enhancement and pore tortuosity reduction (<em>p</em> &lt; 0.001). This study demonstrates that CT restructures compacted soil into hydraulically active systems through breaking plough pan and improving pore structure, providing mechanistic insights for combating soil degradation in ecologically vulnerable black soil regions.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117329"},"PeriodicalIF":5.6,"publicationDate":"2025-05-07","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143911910","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Forest soil respiration showed a saturation threshold in response to increasing nitrogen deposition: Evidence from a mesocosm experiment","authors":"Renshan Li ,&nbsp;Xinkuan Han ,&nbsp;Yanfeng Bai ,&nbsp;Fangfang Zhang ,&nbsp;Honggang Sun ,&nbsp;Weidong Zhang ,&nbsp;Qingpeng Yang ,&nbsp;Silong Wang","doi":"10.1016/j.geoderma.2025.117331","DOIUrl":"10.1016/j.geoderma.2025.117331","url":null,"abstract":"<div><div>Whether there is a N saturation threshold for the response of soil respiration (R_s) to increasing nitrogen (N) deposition remains unclear in forest ecosystems. In this work, a simulated N deposition experiment involving five levels of N addition (0 to 44.8 g N m⁻² yr⁻¹) was performed in a mesocosm experiment platform with young Chinese fir (<em>Cunninghamia lanceolata</em>) trees planted on it. R_s and its autotrophic (R_a) and heterotrophic (R_h) components were measured for four years, and the N saturation threshold was estimated using a quadratic-plus-plateau model. With increasing rate of N addition, R_s and R_a first increased dramatically until the critical N addition rate of 12.2 and 13.6 g N m⁻² yr⁻¹, respectively, and then leveled off. A similar non-linear increase in tree growth was also detected with N addition. In contrast, R_h continued to decrease as N addition increases, primarily a consequence of the N-increased recalcitrance of soil organic C, as evidenced by the decreased gram-negative bacteria biomass coupled with increased polyphenol oxidase activity. Our results indicated (1) that there was a N saturation threshold for the soil respiration, before which respiration rate increased with N addition and such an increase vanished thereafter; and (2) that the N saturation threshold of soil respiration was driven by autotrophic rather than heterotrophic respiration. This study advanced our understanding of the response of forest carbon cycle to growing N deposition.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"458 ","pages":"Article 117331"},"PeriodicalIF":5.6,"publicationDate":"2025-05-06","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143911909","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}