Geoderma最新文献

{"title":"Environmental variables controlling soil aggregate stability across spatial scales and locations in a karst region of southwestern China","authors":"Weichun Zhang ,&nbsp;Jiangwen Li ,&nbsp;Xin Zhang ,&nbsp;Wei Wu ,&nbsp;Hongbin Liu","doi":"10.1016/j.geoderma.2025.117240","DOIUrl":"10.1016/j.geoderma.2025.117240","url":null,"abstract":"<div><div>Information on soil aggregate stability (SAS) is essential for assessing ecosystem services and scaling up soil erosion models. The global contributions of environmental factors (e.g., soil properties, topography, and climate) on SAS at a specific spatial scale are extensively documented. However, the scale- and location-specific controls of these factors are poorly understood. Here, using 2,238 topsoil (0–0.2 m) samples and 24 environmental factors, we quantified SAS variability across different spatial scales and locations in a karst region (43,700 km²) of southwestern China. We found SAS varied mainly at large scale (20 km) followed by medium scale (10 km) and small scale (2 km). Topographic variables, namely, slope, elevation, and plan curvature were key determinants of controlling SAS variability at small scale. Soil organic matter and precipitation were critical drivers affecting SAS variability at medium scale. Precipitation and cation exchange capacity were main factors controlling SAS variability at large scale. Specifically, slope primarily exhibited a negative influence on small-scale SAS variability in the southern region, and a positive effect in the northern region. At medium scale, soil organic matter generally exerted positive effects on SAS. At large scale, the primary influence of precipitation typically differs between the northernmost part and remaining region of the study area. These results reveal the scale- and location-specific controls of environmental factors on SAS that should be considered for digital soil mapping and designing region-based soil management.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"456 ","pages":"Article 117240"},"PeriodicalIF":5.6,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601062","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Organic amendments promote soil phosphorus related functional genes and microbial phosphorus cycling","authors":"Wenchao Wu ,&nbsp;Yangjian Zhang ,&nbsp;Benjamin L. Turner ,&nbsp;Yunlong He ,&nbsp;Xiaodong Chen ,&nbsp;Rongxiao Che ,&nbsp;Xiaoyong Cui ,&nbsp;Xuejun Liu ,&nbsp;Lin Jiang ,&nbsp;Juntao Zhu","doi":"10.1016/j.geoderma.2025.117247","DOIUrl":"10.1016/j.geoderma.2025.117247","url":null,"abstract":"<div><div>Phosphorus (P) mobilization by soil microorganisms plays a crucial role in determining the fertility and productivity of terrestrial ecosystems, yet the synthesis of impact of fertilization strategies on this process remains poorly understood. To fill this knowledge gap, we conducted a <em>meta</em>-analysis of 1082 observations from 85 independent fertilization experiments to evaluate how the abundance and diversity of P related functional genes (<em>phoD</em>, <em>phoC</em> and <em>pqqC</em>) and microbial P cycling responded to fertilizer addition. Overall, we found that amendment with organic matter (OM) alone or with inorganic fertilizer (OM + IF) enhanced soil microbial P (MBP), soil phosphatase activity, and the <em>phoD</em> gene abundance. Conversely, addition of nitrogen (N) fertilizer increased <em>pqqC</em> gene abundance but decreased MBP and <em>phoD</em> gene abundance. P fertilizer increased MBP and the diversity of the <em>phoD</em> gene, while combined NP addition (with or without potassium, K) increased acid phosphatase activity, MBP, <em>pqqC</em> gene abundance and the diversity of the <em>phoC</em> gene. Specifically, the effects of fertilizer addition on rhizosphere properties varied with fertilizer type: OM increased rhizosphere phosphatase activity and <em>phoD</em> gene abundance, whereas P and NP(K) fertilizers decreased them. Furthermore, as annual temperature and precipitation increased, the influence of OM on soil phosphatase activity and <em>phoD</em> gene abundance increased, while the effect of P addition on the Chao1 index of <em>phoD</em> reduced. As experimental duration lengthens, the effect of OM on <em>phoD</em> gene abundance was strengthened, while the effect of N addition was suppressed. Across all fertilizer studies, structural equation models suggested that soil phosphatase activity was closely correlated with soil organic carbon (SOC), soil pH, and <em>phoD</em> or <em>phoC</em> gene abundance. This comprehensive analysis highlights the benefits of OM and OM + IF over synthetic fertilizer for soil microbial P cycling and associated functional genes, providing profound insights into P mobilization and use efficiency in terrestrial ecosystems.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"456 ","pages":"Article 117247"},"PeriodicalIF":5.6,"publicationDate":"2025-03-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Mapping the distribution and magnitude of soil inorganic and organic carbon stocks across Australia","authors":"Wartini Ng ,&nbsp;José Padarian ,&nbsp;Mercedes Román Dobarco ,&nbsp;Budiman Minasny ,&nbsp;Alex B. McBratney","doi":"10.1016/j.geoderma.2025.117239","DOIUrl":"10.1016/j.geoderma.2025.117239","url":null,"abstract":"<div><div>Understanding the presence and dynamics of soil inorganic carbon (SIC) is essential, given its role as a significant sink for atmospheric carbon within the global carbon cycle. In arid and semi-arid regions such as Australia, soils may contain a higher proportion of SIC compared to soil organic carbon (SOC). However, the relative magnitudes of SIC and SOC in these areas remain unclear. This study resolves this uncertainty by estimating Australia’s total soil carbon stocks, with a particular focus on the inorganic carbon fraction. The SIC content was predicted using a two-step quantile regression forests mixture model of classification and regression for six depth intervals: 0–5 cm, 5–15 cm, 15–30 cm, 30–60 cm 60–100 cm, and 100–200 cm at 90 m × 90 m resolution. Equivalent SOC maps were derived from our previous study. The SIC models utilised a compilation of environmental covariates and inorganic carbon content related data from pH (n = 41,590), effervescence (n = 15,105) and calcium carbonate measurements (n = 5,776). Both the classification model (kappa = 0.533) and regression model (R² = 0.468) for SIC achieved fair accuracy. The elevated concentration of SIC is consistent with the distribution of calcareous soils, and mainly accumulates in the lower depth. Our estimates indicate that the total carbon stock in Australian soils (0–2 m) is 78.9 Pg, with 44 % comprised of SIC. In the upper 1 m depth, carbon stock from SIC is half that of SOC (17.57 Pg vs. 37.75 Pg); however, in the lower depth interval of 1–2 m, SIC is three times larger than SOC (17.48 Pg vs. 6.13 Pg). In the arid and semi-arid regions of Australia, the amount of SIC stock (34.1 Pg C) is slightly larger than that of SOC stock (29.82 Pg C). This study provides a baseline measure of soil as a carbon sink in the forms of organic carbon and inorganic carbon within Australia.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"456 ","pages":"Article 117239"},"PeriodicalIF":5.6,"publicationDate":"2025-03-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143580658","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Plateau zokor disturbances transform the stability and functional characteristics of soil fungal communities","authors":"Xiaojuan Zhang ,&nbsp;Zhuangsheng Tang ,&nbsp;Jie Yang ,&nbsp;Saman Herath ,&nbsp;Zhiwen Wang ,&nbsp;Yiming Wang ,&nbsp;Guangjun Chen ,&nbsp;Lei Yue","doi":"10.1016/j.geoderma.2025.117232","DOIUrl":"10.1016/j.geoderma.2025.117232","url":null,"abstract":"<div><div>As crucial regulators of the ecosystem functions, soil microbes are facing a range of challenges including ecological degradation caused by small mammal disturbances. These disturbances not only threaten biodiversity but also affect the healthy functioning of ecosystems. Effects of plateau zokor (<em>Eospalax baileyi</em>) disturbances on the complexity, stability and assembly processes of belowground microbial networks remain unclear. In this study, we employed ITS rRNA gene amplicon sequencing to systematically investigate fungal network properties, assembly mechanisms, functional potential, and the links to plant-soil functions in soil fungal communities through various stages of zokor mound succession: (i) new mounds (NM), (ii) semi-new mounds (SM), (iii) old mounds (OM) and (iv) pristine grassland (CK), as a control. The results demonstrated that zokor disturbances significantly altered plant species diversity and soil properties, simultaneously affecting the composition and structure of soil fungal communities. Disturbances increased the complexity of fungal community networks but decreased their stability. Moreover, dispersal limitation and homogeneous selection were identified as the primary mechanisms that shape fungal community structure. Functional potential analysis revealed that zokor disturbances led to a decline in the relative abundance of lichenized fungi and plant saprotrophs. Multiple environmental factors, including soil pH, soil organic carbon (SOC), and total phosphorus (TP) were identified as pivotal in driving changes in soil fungal communities. These results deepen our comprehension of the impacts of small mammal disturbances on fungal community characteristics in the Tibetan Plateau grassland ecosystem and provide valuable insights into the potential mechanisms sustaining fungal diversity in extreme environments.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"455 ","pages":"Article 117232"},"PeriodicalIF":5.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143508462","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The role of pyrogenic carbon addition after wildfires in the boreal forest of China: Impact on plant–soil–microbial ecological stoichiometry","authors":"Xu Dou ,&nbsp;Jianyu Wang ,&nbsp;Kajar Köster ,&nbsp;Cheng Yu ,&nbsp;Yuexiao Ren ,&nbsp;Long Sun ,&nbsp;Tongxin Hu","doi":"10.1016/j.geoderma.2025.117237","DOIUrl":"10.1016/j.geoderma.2025.117237","url":null,"abstract":"<div><div>Pyrogenic carbon (PyC) is a common byproduct of wildfires in terrestrial systems; however, its role in fire-prone forest ecosystems, particularly cold boreal forests, remains unclear. Ecological stoichiometry is a valuable tool for studying interactions within plant–soil–microbial continuum systems, which could help us understand post-fire changes in boreal forest ecosystems. In this study, we manipulated different additions of PyC in a forest of Dahurian larch (<em>Larix gmelinii</em>) after a wildfire to investigate the effects of PyC on plant–soil–microbial ecological stoichiometry. We engineered PyC under controlled conditions to simulate that produced by wildfires. The experimental design included no PyC addition (C0), 0.5 kg m⁻² PyC addition (C1), 1.0 kg m⁻² PyC addition (C2), and no fire as a control (CK). One year after PyC manipulation, understory vegetation and soil samples (0–10 cm depth) were collected to investigate how PyC addition affects plant–soil–microbial carbon (C), nitrogen (N), and phosphorus (P) stoichiometry. Our results showed that PyC addition (C1, and C2) increased plant biomass, particularly in the green tissues (35–53 % higher than that in the CK and 59–80 % higher than that in the C0 treatment). The C2 treatment also increased the plant C and N contents but did not significantly affect plant P content. PyC addition led to an increase in soil microbial biomass N (MBN) and P (MBP), altered the microbial biomass C:N:P ratio (to 27:1:1), and disrupted the microbial dynamic balance, indicating a possible shift towards a bacterial-dominated community. In boreal forest soils, post-fire PyC manipulation elevated soil organic C (SOC) and total P (STP). As there were no changes in soil total N (STN), the addition of PyC also increased the soil C:N and C:P ratios. Our findings highlight the potential of PyC as a soil conditioner that enhances plant biomass and alters nutrient cycling in boreal forests. However, PyC effects are modulated by soil resource availability and the nutrient environment. Further studies are required to elucidate the mechanisms underlying these differential nutrient responses.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"455 ","pages":"Article 117237"},"PeriodicalIF":5.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526584","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"A meta-analysis reveals earthworms as mutualists rather than predators of soil microorganisms","authors":"Manuel Blouin ,&nbsp;Aïssa Robin ,&nbsp;Lysandre Amans ,&nbsp;Frédérique Reverchon ,&nbsp;Isabelle Barois ,&nbsp;Patrick Lavelle","doi":"10.1016/j.geoderma.2025.117238","DOIUrl":"10.1016/j.geoderma.2025.117238","url":null,"abstract":"<div><div>Microorganisms constitute the largest biomass on Earth after plants, and earthworms are one of the main components of animal biomass. Both are critical drivers of soil functions and ecosystem services. Studies report either positive or negative effects of earthworms on soil microbial communities, leading to contrasting views on whether microorganisms serve as prey or mutualists for earthworms. This <em>meta</em>-analysis aimed to settle this debate, and examines how biotic and abiotic factors affect earthworm impacts on microbial abundance and diversity. Based on a selective search retaining only genuinely quantitative approaches, we kept 169 observations, showing that, on average, earthworms increased bacterial abundance by 16.5 % and fungal abundance by 31.4 %. Bacterial species richness rose by 8.5 % in the presence of earthworms, but fungal richness was not significantly affected. Epigeic and anecic earthworms had more notable effects than endogeics. Plant presence in experimental designs strongly amplified earthworms’ effects on bacterial (+30 %) and fungal (+97 %) abundances. The largest earthworm-induced effects were observed in carbon- and nitrogen-rich soils and at low pH, while the addition of organic matter reduced these effects. Comparing microbial abundance in earthworm casts to control units without earthworms revealed effect sizes two- to three-fold greater (for bacteria and fungi, respectively) than when using the soil surrounding earthworm casts as a control. Our <em>meta</em>-analysis demonstrates that, despite ingesting some microorganisms, earthworms have a net positive effect on their abundance, positioning them as mutualists rather than predators of bacteria and fungi.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"455 ","pages":"Article 117238"},"PeriodicalIF":5.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526583","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Soil quality improvement on Qinghai-Tibet Plateau induced by soil hydrothermal changes from 1980s to 2020s","authors":"Kuan Chen ,&nbsp;Jingyao Suo ,&nbsp;Xiaodong Song ,&nbsp;Yiyao Liu ,&nbsp;Xiang Xiang ,&nbsp;Yingping Pan ,&nbsp;Jiarui Wang ,&nbsp;Liang Ren ,&nbsp;Xiaodong Ge ,&nbsp;Xia Xu ,&nbsp;Xiuchen Wu ,&nbsp;Lei Duan ,&nbsp;Yongmei Huang","doi":"10.1016/j.geoderma.2025.117235","DOIUrl":"10.1016/j.geoderma.2025.117235","url":null,"abstract":"<div><div>The Qinghai-Tibet Plateau (QTP), as the world’s Third Pole, has experienced a sharp trend of warming and humidifying in recent decades within the context of global climate change. Under these circumstances, the soil nutrient cycling has been significantly modified. However, whether the soil quality had changed over recent decades on QTP remains unclear. In this study, we calculated, and drew high-resolution maps of the soil quality index (SQI) on QTP using soil property data in 1980s and 2020s. Results showed significantly an increasing trend of soil quality over the past four decades. The variation in trends of four typical ecosystems, more specifically, alpine cushion vegetation showing the most notable increase, followed by alpine meadow and alpine steppe, while forest &amp; shrub exhibiting the smallest increase in soil quality. This implied that regions with more significant SQI changes correspond to stronger climate change. Through attribution analysis of 10 factors affecting the variation in SQI, including climate, soil hydrothermal, vegetation, and human activities, we found that the improvement in soil quality were predominantly driven by soil hydrothermal conditions. Additionally, we observed a pronounced increase in nitrogen limitation, with the factors contributing to this trend varying across different ecosystems. Our study emphasizes the warning of intensified nitrogen limitation, and, under the context of climate change, this phenomenon is likely to become increasingly severe in the future.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"455 ","pages":"Article 117235"},"PeriodicalIF":5.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143528735","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Long-term regulation of maize crop residue carbon accumulation in soil and aggregates by epigeic and endogeic earthworms is tillage regime-specific","authors":"Xinyu Zhu ,&nbsp;Yunchuan Hu ,&nbsp;Zhen He ,&nbsp;Donghui Wu ,&nbsp;Andrey S. Zaitsev","doi":"10.1016/j.geoderma.2025.117231","DOIUrl":"10.1016/j.geoderma.2025.117231","url":null,"abstract":"<div><div>Earthworms influence soil carbon (C) sequestration by modulating the balance between plant residue C incorporation and soil C mineralization below ground. The knowledge of the prolonged effects and backstaging mechanisms of C sequestration by earthworms belonging to different ecological groups in no-tillage (NT) and conventional tillage (CT) agroecosystems is still surprisingly sketchy. Therefore, we analyzed the contribution of the epigeic species <em>Eisenia nordenskioldi</em> (Eisen) and the endogeic species <em>Metaphire tschiliensis</em> (Michaelsen) to the distribution of C in soil and soil aggregates of different sizes from the ¹³C-labeled maize residue. For this, we ran a 337-day-long mesocosm experiment with simulated NT and CT systems. At the end of the experiment, epigeic and endogeic earthworm treatments in NT soil significantly increased SOC concentration by 16.61% and 17.31%, respectively if compared with the situation on day 40. However, no significant effects were observed in CT soil. In NT soil, the presence of <em>M. tschiliensis</em> significantly increased residue-derived C in SOC, whereas this effect was not significant in CT soil. The presence of <em>M. tschiliensis</em> increased the ¹³C content in all soil aggregate size classes in both NT and CT soils at the end of the experiment. The interaction between the two earthworm species treatments significantly positively affected the ¹³C content across all soil aggregate size classes in NT soil. This means that in NT soil, earthworms can aid the accumulation of larger amounts of ¹³C via enriching soil aggregates with C derived from crop residues. Our study further demonstrated that compared to epigeic earthworms, endogeics are more likely to promote the retention of maize residue-derived C in soil. Such differential contribution of the two ecological groups of earthworms explored to the stabilization of C in aggregates highlights the need for functionally diverse soil macrofauna in agroecosystems to achieve synergies in the delivery of essential ecological services in low input agriculture.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"455 ","pages":"Article 117231"},"PeriodicalIF":5.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143547101","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Nitrogen addition promotes the coupling of deep soil carbon and nitrogen under different vegetation restoration types in the Chinese Loess Plateau","authors":"Shihao Gong ,&nbsp;Xiaoxia Zhang ,&nbsp;Hengshuo Zhang ,&nbsp;Lianwei Gao ,&nbsp;Tonggang Zha","doi":"10.1016/j.geoderma.2025.117236","DOIUrl":"10.1016/j.geoderma.2025.117236","url":null,"abstract":"<div><div>Carbon-nitrogen coupling is important to maintain various functions in forest ecosystems and is thus, an important indicator of forest ecosystem health. However, the magnitude of this indicator’s importance to environmental changes remains virtually unknown, especially for deep soils across vegetation types. In this study, four representative sites, namely <em>Pinus tabulaeformis</em> forest, <em>Robinia pseudoacacia</em> forest, <em>Pinus tabulaeformis</em> x <em>Robinia pseudoacacia</em> mixed forest, and <em>Populus davidiana</em> x <em>Quercus wutaishanica</em> natural secondary forest, were selected as representatives of typical artificial and natural forests. A one-year N addition experiment was conducted to analyze C-N coupling conditions of different vegetation restoration types, and soil properties in the 0 – 100 cm layer, litter traits, and rainfall distribution characteristics were measured and compared during the growing season. (1) Soil C and N in artificial forests decoupled with increasing soil depth, while soil C and N were highly coupled among all soil depths in natural forest. (2) N addition had a greater effect on deep soil nutrient accumulation compared to topsoil. (3) N addition decreases the rates of change of deep soil N, which, in turn, enhanced the C and N coupling. (4) Moreover, further analyses with a structural equation model showed that summer precipitation is the key regulator of soil C:N ratio in topsoil. Soil pH, litter C:N ratio, and N deposition were primarily responsible for controlling deep soil C and N coupling. These results indicate that N addition and vegetation restoration types affect soil C and N coupling and should be taken into consideration when assessing deep soil C and N biogeochemical cycles. The importance of deep soil should be considered as much as possible during afforestation on the Loess Plateau. Afforestation should be conducted in a way of natural restoration. This study provides novel insights into the regulatory mechanisms of C and N biogeochemistry and the afforestation patterns of vegetation restoration in arid and semi-arid regions.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"455 ","pages":"Article 117236"},"PeriodicalIF":5.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143547103","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"The problematic case of data leakage: A case for leave-profile-out cross-validation in 3-dimensional digital soil mapping","authors":"Kingsley John ,&nbsp;Daniel D. Saurette ,&nbsp;Brandon Heung","doi":"10.1016/j.geoderma.2025.117223","DOIUrl":"10.1016/j.geoderma.2025.117223","url":null,"abstract":"<div><div>Data leakage occurs when there is an overlap between the data used for model fitting and hyperparameter tuning, and those used for testing. This overlap biases the model performance, making it uninformative regarding the model’s ability to generalize. This is a significant issue in machine learning and predictive soil mapping, compromising model reliability. To demonstrate this issue, the 3-dimensional (3D) digital soil mapping (DSM) approach, whereby depth is used as a predictor of soil properties, was investigated. We compare two common approaches from the literature: leave-sample-out cross-validation (LSOCV) versus leave-profile-out cross-validation (LPOCV). Here, we argue that LSOCV results in contamination of the test dataset due to the potential vertical autocorrelation of soil properties from different samples within the same profile, and a more appropriate approach for testing 3D DSM models should be to fully partition all soil samples from the same profile to either the training or test dataset (i.e., LPOCV). Using the Ottawa region of Ontario, Canada, as a case study, cation exchange capacity (CEC), clay content, pH, and total organic carbon (TOC) were predicted using machine learning, and the discrepancy in accuracy metrics was reported. Furthermore, we evaluated the effects of data augmentation (i.e., the creation of additional synthetic data points from the original data) on accuracy metrics, a common practice in 3D DSM. Here, it was shown that with the augmented dataset, LSOCV generated overly optimistic accuracy metrics (e.g., CCC) that were 29–62% higher than LPOCV, while for the non-augmented data, the accuracy metrics were 8–18% higher, suggesting that vertical autocorrelation had a strong influence on inflating model accuracy through data leakage. As such, we strongly urge DSM practitioners to provide greater clarity when describing how model accuracy metrics were ascertained and to consider the use of LPOCV when applied to 3D DSM. This brings about broader concerns that policymakers and stakeholders may use map products with the false impression that the maps are more accurate than they are. Future research should focus on refining DSM methods and considering data structure to prevent data leakage in modelling soil properties.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"455 ","pages":"Article 117223"},"PeriodicalIF":5.6,"publicationDate":"2025-03-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143526591","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":1,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}