Geoderma最新文献

{"title":"A novel perspective on near-surface soil freeze states: Discontinuity of the freeze process","authors":"Xiqiang Wang ,&nbsp;Rensheng Chen ,&nbsp;Chuntan Han ,&nbsp;Xueliang Wang","doi":"10.1016/j.geoderma.2025.117258","DOIUrl":"10.1016/j.geoderma.2025.117258","url":null,"abstract":"<div><div>The freeze state of near-surface soil is crucial for regional hydrology, ecosystems, and infrastructure, yet its discontinuous nature remains largely unknown. This research addresses this gap by employing soil temperatures at a depth of 5 cm from 335 meteorological stations across China, introducing three novel indicators—continuous freeze frequency, freeze fragmentation index, and freeze continuity index––to quantify freeze process discontinuity. The findings reveal significant regional variations in freeze discontinuity across China, primarily shaped by latitude. Further analysis reveals that snow depth can explain 27.3 % and 20.0 % of the variation in freeze continuity and continuous freeze frequency, respectively, while air temperature can account for 30.6 % of the variation in freeze fragmentation. The structural equation model suggests that precipitation, sunshine duration, and air temperature exert both direct and indirect effects on freeze discontinuity, and snow cover plays a key role in mediating the influence of other environmental variables on freeze discontinuity. This study offers a novel analytical perspective on the soil freeze state, enhancing our understanding of freeze dynamics under climate warming.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"456 ","pages":"Article 117258"},"PeriodicalIF":5.6,"publicationDate":"2025-03-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143636298","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":"Ensemble and transfer learning of soil inorganic carbon with visible near-infrared spectra","authors":"Yu Wang ,&nbsp;Keyang Yin ,&nbsp;Bifeng Hu ,&nbsp;Yongsheng Hong ,&nbsp;Songchao Chen ,&nbsp;Jing Liu ,&nbsp;Lili Yang ,&nbsp;Jie Peng ,&nbsp;Zhou Shi","doi":"10.1016/j.geoderma.2025.117257","DOIUrl":"10.1016/j.geoderma.2025.117257","url":null,"abstract":"<div><div>Soil inorganic carbon (SIC) dominates the soil carbon pools in semi-arid and arid areas globally. Variations in the SIC pool would substantially affect the atmospheric CO₂ concentrations. The rapid and accurate measurement of SIC content using visible near-infrared (Vis-NIR) spectroscopy is of high significance for the management of soil carbon pools in semi-arid and arid regions. Ensemble learning is a novel and advanced modeling approach. However, it has been applied less in soil spectroscopy, and its transfer capability has not been evaluated. Therefore, we hypothesized that the use of the ensemble technique could further SIC prediction accuracy and have a better model transfer capability. In this study, a stacking model was developed using 990 soil samples collected from the Alar Reclamation region in South Xinjiang, China. The stacking model consists of 10 base models (support vector machine (SVM), partial least squares algorithm (PLSR), multi-layer perceptron (MLP), etc.). Two strategies (hyperparameter-adjusted and −unadjusted) were used to transfer the model to other target areas including Shaya and Wensu Counties on the southern border of China. Our results demonstrate that the SIC content could be predicted accurately using the stacking models (R²_p = 0.81). The stacking model outperformed all the individual models and significantly improved the prediction accuracy of SIC. The R²_p of the stacking models improved by 0.05–0.21, and the root mean square error (RMSE_P) reduced by 0.33–1.44 g kg⁻¹. Additionally, the stacking models displayed superior model transfer capability. Compared with direct transfer, the stacking model with fine-tuning of the hyperparameters displayed better model stability and generalization. Moreover, the average R²_p improved by over 0.09 compared with the stacking model with unadjusted hyperparameters. Overall, stacking ensemble learning is a potential method for predicting SIC with good transfer capabilities. Our results provide new tools and strategies for the accurate estimation of SIC in semi-arid and arid regions.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"456 ","pages":"Article 117257"},"PeriodicalIF":5.6,"publicationDate":"2025-03-15","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628121","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":"Molybdenum regulates phosphorus cycling species diversity and improves soil phosphorus availability through key flavonoids in the soybean (Glycine max)","authors":"Xiaoming Qin ,&nbsp;Yining Liu ,&nbsp;Qingyun Xu ,&nbsp;Chengxiao Hu ,&nbsp;Songwei Wu ,&nbsp;Xuecheng Sun ,&nbsp;Qiling Tan","doi":"10.1016/j.geoderma.2025.117242","DOIUrl":"10.1016/j.geoderma.2025.117242","url":null,"abstract":"<div><div>Applying molybdenum (Mo) fertilizer can improve soil phosphorus (P) bioavailability, reduce the need for P fertilizers in agriculture, and enhance crop growth. However, the precise mechanisms behind these benefits are not yet fully understood. For the first time, we demonstrate the impact of Mo application on the transformation of P forms, metabolites, and microorganisms in the soybean rhizosphere. We carried out a series of pot experiments under controlled conditions, applying varying levels of Mo and collecting samples from the soybean rhizosphere across different treatments to analyze P forms, metabolic profiles, and microbial communities comprehensively. Mo application enhanced soybean P uptake and growth by promoted the conversion of aluminum-bound P (Al-P) and organic P to available P. The underlying mechanism involves the regulatory effect of Mo on the abundance of metabolites in the soil, thereby reshaping the structure of the rhizosphere microbial community. Two key Mo-mediated flavonoids, chrysin (Cs) and phlorizin (Pz), significantly promoted soybean growth and P absorption. Subsequently, Soil metagenomics and phosphate-solubilizing bacteria (PSB) addition experiments confirmed that these flavonoids increased P cycling genes (e.g., <em>gcd</em> and <em>phoD</em>) and microorganisms, facilitating stable P transformation into labile P, and aiding PSB (<em>Bacillus subtilis</em>) in further enhancing soil P availability. In summary, we have demonstrated for the first time that trace metals regulate the abundance of soil P cycling microorganisms by influencing crop-secreted flavonoids. This ultimately improves soil P bioavailability, providing a new insight for sustainable agricultural development.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"456 ","pages":"Article 117242"},"PeriodicalIF":5.6,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621463","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":"Nuclear magnetic resonance relaxometry to characterise the decomposition degree of peat soils","authors":"Stephan Costabel,&nbsp;Claus Florian Stange","doi":"10.1016/j.geoderma.2025.117244","DOIUrl":"10.1016/j.geoderma.2025.117244","url":null,"abstract":"<div><div>An adequate response to the ecological challenges associated with the traditional peatland management and corresponding site-specific measures require spatial information on soil properties and functions, most of which are related to the degree of peat decomposition. Our laboratory study tests the expectation that NMR relaxometry provides simple and rapidly available proxies characterising the decomposition state of peat. We observe that the mean NMR relaxation time is correlated with established soil physical parameters quantifying peat decomposition: water absorption index, unit water content, bulk density and von Post index. The higher the decomposition degree, the faster is the NMR relaxation, which mainly results from a decreasing pore space. Correlation maps between the T₁ and T₂ relaxation times identify hydrogel-like effects in weakly decomposed peat that vanishes if the material decomposes under aerobic conditions. T₁/T₂ ratios of more than ten are observed for peat material with cellular components in contrast to earthified topsoil peat with ratios of less than two. Our attempt to transfer the NMR relaxation data to estimates of water retention functions is partially successful. However, our results also indicate that the relaxation mechanisms in peat are not only controlled by pore sizes. We observe increasing surface relaxivities with increasing decomposition degree, which is most likely the result of a chemical transformation of the pore surface that alters its paramagnetic properties. The magnitude of this increase is significantly higher for T₁ than for T₂, because the interaction of water molecules and pore surface affects the corresponding NMR relaxation mechanisms differently.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"456 ","pages":"Article 117244"},"PeriodicalIF":5.6,"publicationDate":"2025-03-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143628120","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":"Land use effects on soil carbon retention through glomalin-mediated aggregation","authors":"Ying Zhao ,&nbsp;Asim Biswas ,&nbsp;Mingtao Liu ,&nbsp;Xiaozeng Han ,&nbsp;Xinchun Lu ,&nbsp;Xu Chen ,&nbsp;Xiangxiang Hao ,&nbsp;Wenxiu Zou","doi":"10.1016/j.geoderma.2025.117252","DOIUrl":"10.1016/j.geoderma.2025.117252","url":null,"abstract":"<div><div>The glomalin-related soil protein (GRSP), produced by arbuscular mycorrhizal fungi, plays a critical role in soil organic carbon (SOC) storage and stabilization across terrestrial ecosystems. We examined the effects of four contrasting land-use types (bare land, cropland, grassland, and woodland) originating from the same soil matrix on GRSP dynamics, soil aggregation, and SOC accumulation. We found that grassland and woodland ecosystems exhibited significantly higher contents of macroaggregates (&gt;0.25 mm), SOC, total nitrogen (TN), total GRSP (TG), easily extractable GRSP (EEG) and aggregate stability compared with cropland and bare land. Across all land uses, the EEG/SOC and TG/SOC ratios in Mi and SC were higher than other aggregates sizes. Correlation analyses showed that TG was significantly and positively correlated with SOC in bulk soil and macroaggregates (&gt;2 mm), while EEG exhibited significant positive correlations with SOC in smaller macroaggregates and microaggregates. Furthermore, GRSP was strongly and positively correlated with aggregate stability, and the content of TG and the TG/SOC ratio were mainly influenced by microbial biomass carbon (MBC) and SOC. Our findings highlight the contrasting correlations of TG and EEG to SOC storage across aggregate size classes, with TG playing a more prominent role in bulk soil and large macroaggregates, and EEG more significantly associated with SOC accumulation in small macroaggregates and microaggregates. This study advances our understanding of the mechanisms by which GRSP facilitates SOC sequestration and soil aggregate formation under different land-use regimes, informing sustainable land management strategies for climate change mitigation.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"456 ","pages":"Article 117252"},"PeriodicalIF":5.6,"publicationDate":"2025-03-13","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143621462","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":"In situ visualization of soil profile acidification and processes following nitrogen fertilization and liming","authors":"Jingjing Tao ,&nbsp;Lichao Fan ,&nbsp;Tao Jiang ,&nbsp;Xiaona Song ,&nbsp;Mengzhen Zhao ,&nbsp;Jianbin Zhou ,&nbsp;Yakov Kuzyakov ,&nbsp;Kazem Zamanian","doi":"10.1016/j.geoderma.2025.117243","DOIUrl":"10.1016/j.geoderma.2025.117243","url":null,"abstract":"<div><div>Soil pH is the master variable of soil properties and understanding its spatiotemporal changes <em>in situ</em> is key to unveiling numerous biogeochemical processes. The development of non-invasive imaging techniques provides the possibility to visualize and localize soil pH changes depending on various factors, e.g. fertilization and climate. Herein, the optodes pH mapping system was used to study the effects of eight fertilizer types including chicken manure, Ca(NO₃)₂, Mg(NO₃)₂, KNO₃, NH₄NO₃, (NH₄)₂SO₄, NH₄H₂PO₄, and urea on the spatiotemporal distribution of soil pH with and without liming at 10 °C and 25 °C. Ammonium-based fertilizers, especially NH₄NO₃, (NH₄)₂SO₄, and NH₄H₂PO₄ strongly decreased soil pH by a maximum of 1.4 ± 0.16 units at both temperatures. The 0–2 cm, where fertilizers were applied, had the highest pH decreases, from where the acidity rapidly diffused to depth. The acidified depth extended down to 4.5 ± 0.14 cm over 60 d. Chicken manure increased the pH within 5 d, but the pH decreased again after 60 d. Soil temperature was a strong controller of acidity generation and transport to depth after fertilization: pH decreased by 0.1 ± 0.07–0.3 ± 0.07 units more at 25 °C than 10 °C due to increased activity of nitrifying microorganisms, and higher temperature accelerated the spatiotemporal dynamics of soil acidity. Although pH increased shortly after liming compared to unlimed soils, it decreased after adding ammonium-based fertilizers. Therefore, N fertilizer types and temperature should be considered for having a more efficient fertilization management with less consequences for soil acidification. The planar optode is a powerful non-invasive imaging technique that enables <em>in situ</em> visualization of the spatiotemporal changes of soil pH profile after fertilization.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"456 ","pages":"Article 117243"},"PeriodicalIF":5.6,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143609988","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":"Biochar’s electron shuttle potential mitigates N2O emissions by counteracting the stimulatory effect of rice root iron plaque","authors":"Dan Yuan ,&nbsp;Sihuan Wu ,&nbsp;Chunsheng Hu ,&nbsp;Jiahuan Tang ,&nbsp;Shuping Qin","doi":"10.1016/j.geoderma.2025.117248","DOIUrl":"10.1016/j.geoderma.2025.117248","url":null,"abstract":"<div><div>Iron (Fe) plaque on rice roots can enhance nitrous oxide (N₂O) emissions from paddy soil, primarily through Fe(II) oxidation-coupled denitrification. In this study, our hypothesis is that biochar will reduce N₂O emissions via an electron shuttle and complete denitrification. To test this hypothesis, we performed laboratory microcosm experiments using a paddy soil-Fe plaque system amended with biochar. We examined the effects of biochar on soil N₂O emissions, soil microbial community composition, and denitrifying functional gene. Furthermore, we evaluated potential correlations between biochar’s electron shuttle capacity and N₂O emissions, as well as the N₂O/(N₂O + N₂) ratio derived from denitrification processes.</div><div>Our results demonstrated that, in the absence of rice straw biochar, N₂O emissions were doubled in the presence of Fe plaque. Interestingly, the addition of 1 % biochar to the paddy soil neutralized the difference in N₂O emissions between the Fe plaque and control treatments. Furthermore, biochar addition enhanced the abundance of Fe(II)-oxidizing denitrifiers (e.g., <em>Bacillus</em> and <em>Zoogloea</em>) at the genus level and upregulated key denitrification functional genes (e.g., <em>nirK</em> and <em>nosZ</em>) associated with N₂O mitigation. Importantly, oxidative treatment of biochar with H₂O₂ at varying concentrations reduced its electron donation capacity, which significantly weakened its ability to counteract Fe plaque-induced stimulation of N₂O emissions. This efficacy was directly proportional to the biochar’s electron transfer capabilities.</div><div>These results highlight the critical role of biochar’s electron transfer function in counteracting the stimulatory effect of Fe plaque on N₂O emissions. We conclude that adding biochar with strong electron transfer capabilities is a promising strategy to curb the Fe plaque-induced priming effect on N₂O emissions in paddy soils. The application of just 1 % biochar at the rice seedling stage may effectively mitigate N₂O emissions in paddy soils.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"456 ","pages":"Article 117248"},"PeriodicalIF":5.6,"publicationDate":"2025-03-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143601063","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":"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}