Geoderma Regional最新文献

{"title":"Organic carbon stocks across various land use systems in Sandy Ultisols and Oxisols in Brazil","authors":"Maria Cecília Vieira Totti ,&nbsp;Yuri Lopes Zinn ,&nbsp;Sérgio Henrique Godinho Silva ,&nbsp;Bruno Montoani Silva ,&nbsp;Fernanda Almeida Bócoli ,&nbsp;Vanêssa Lopes de Faria ,&nbsp;Andrés Olaya Montes ,&nbsp;Salvador Francisco Acuña-Guzman ,&nbsp;Alexandre Uezu ,&nbsp;Laury Cullen Junior ,&nbsp;Vinícius Ferreira Fernandes ,&nbsp;Junior Cesar Avanzi","doi":"10.1016/j.geodrs.2025.e00924","DOIUrl":"10.1016/j.geodrs.2025.e00924","url":null,"abstract":"<div><div>Soil organic carbon (SOC) is a major carbon pool that can be easily affected by land use change, especially in tropical humid sandy soils, where organic decomposition is fast and SOC stabilization is weak. Here, we assessed SOC stocks in coarse-textured Oxisols and Ultisols under six contrasting land uses in western São Paulo, Brazil, an area marked by warm temperatures, within the Atlantic Rainforest biome. Soils were sampled for bulk density and SOC content to a 1-m depth in areas under a) primary native forest, b) native forest restoration, c) pastures, d) sugarcane, e) cassava, and f) annual crops. Even under primary forests, SOC stocks were low relatively to other Brazilian soils under cooler climates and with finer textures, and the effect of land use changes varied with soil type. In both soil types, the lowest SOC stocks occurred under cassava cultivation, a traditional indigenous crop with low soil coverage and which requires intensive soil disturbance for harvesting. In Ultisols, forest restoration and sugarcane presented the highest SOC stocks, whereas in Oxisols, the highest stocks occurred under primary forests and pastures, suggesting that gramineous perennial crops with little soil disturbance are effective in preserving or even sequestering SOC in these areas. When only primary forests are compared, SOC stocks in Oxisols were higher than in Ultisols, probably due the effect of higher soil bulk densities on the Ultisols, rendering root development and thus SOC accrual in subsoil more difficult.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"40 ","pages":"Article e00924"},"PeriodicalIF":3.1,"publicationDate":"2025-01-26","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144470","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Eutrophic soils and weathering levels influence the distribution of seasonally dry forests in Brazil","authors":"Sara Ramos dos Santos ,&nbsp;Carolina Malala Martins Souza ,&nbsp;David Lukas de Arruda ,&nbsp;Danilo de Lima Camêlo ,&nbsp;Jairo Tronto ,&nbsp;Greice Leal Pereira ,&nbsp;Danilo Cesar de Mello ,&nbsp;Wilson Tadeu Lopes da Silva ,&nbsp;Liovando Marciano da Costa ,&nbsp;Carlos Ernesto Gonçalves Reynaud Schaefer","doi":"10.1016/j.geodrs.2025.e00921","DOIUrl":"10.1016/j.geodrs.2025.e00921","url":null,"abstract":"<div><div>Seasonally Dry Forests, or ‘Dry Forests,’ are characterized by deciduous vegetation that sheds leaf during the dry season due to strong soil moisture stress. Despite their ecological significance, as part of the Atlantic Forest realm, research on the diversity, genesis, and soil-vegetation interactions in these ecosystems remains limited. This study investigated the soil attributes of Dry Forests of an ecotonal zone, comparing with the neighboring biomes, the Caatinga (Steppe Savanna) and Cerrado (Brazilian Savanna). We analyzed 16 soil profiles, evaluating their physical, chemical, and mineralogical properties using Principal Component Analysis (PCA). Dry Forest soils (DFS) showed higher amounts of exchangeable cations such as Ca²⁺, Mg²⁺, and K⁺ (Sum of Bases: 2.84–14.79 cmol_c dm⁻³ in the surface horizons) and no detectable Al³⁺. The clay fraction of DFS is mainly illite and kaolinite. The PCA results (PC1: 29.4 %) revealed that Dry Forest soils, particularly on limestone, are more fertile than adjacent Caatinga and Cerrado soils. In contrast, according to the interpretation of PC2 (19.5 %) Cerrado soils are much more weathered and nutrient-depleted (Sum of Bases: 0.37–1.29 cmol_c dm⁻³ in the surface horizons), while Caatinga soils exhibit an intermediate fertility (Sum of Bases: 1.48–21.81 cmol_c dm⁻³ in the surface horizons), and less weathered. The lithologies under DFS at northern Minas Gerais are limestones of the Bambuí Group, resistant sedimentary rocks of the Macaúbas Group, and Granite/gneisses of the Crystalline Basement, which strongly influence soil fertility, mineralogy, and weathering degree. The higher nutrient levels and organic matter contents (2.05–12.03 % in the surface horizons) in DFS support greater productivity and biomass accumulation. These findings highlight the ecological significance of DFS on diverse geological substrates, offering insights for conservation, sustainable management, and ecological restoration in the face of increasing deforestation and land degradation threats.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"40 ","pages":"Article e00921"},"PeriodicalIF":3.1,"publicationDate":"2025-01-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144467","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Transformation of Chernozem by increasing land use intensity in suburban Hajdúság, Eastern Hungary","authors":"Tibor József Novák,&nbsp;Áron Béni,&nbsp;Rita Kremper,&nbsp;Evelin Juhász,&nbsp;Ida Kincses,&nbsp;Zsolt Sándor,&nbsp;Magdolna Tállai,&nbsp;Andrea B. Kovács","doi":"10.1016/j.geodrs.2025.e00920","DOIUrl":"10.1016/j.geodrs.2025.e00920","url":null,"abstract":"<div><div>Chernozem under different agricultural land use were compared in a suburban area: three on cropland with different land use histories; one in an area of complex cultivation; one fallow; and one under grassland, considered to be in close to natural state, as a control. Soil profiles at each site were described and classified, and chemical characteristics analyzed in detail. Topsoil (0-40 cm) bulk density (BD), total organic carbon (TOC), total nitrogen (TN), ammonium lactate-extractable P, K, Ca and Mg were measured, and microbiological communities were characterized by phospholipid-fatty acid (PLFA) markers. We found significantly increased BD but decreased TOC and TN in the cultivated sites compared to the control. Values of ammonium lactate-extractable P (P-AL) were higher at the natural site, but Ca-AL, Mg-AL and K-AL content of the cultivated and mineral-fertilized agricultural sites were higher than or equal to the grassland site. Total microbiological activity correlates significantly positively with TOC and TN and negatively with the BD. Sites with perennial vegetation cover and higher biodiversity showed greater microbiological activity and, in case of the arbuscular mycorrhizal fungi, actinobacteria and anaerobe bacteria, the differences are significant. Despite the nutrient depletion and lesser microbiological activity, cropland sites preserved their taxonomic status as Chernozem. Sites that have undergone more extreme human impacts before the recent land use had lost their diagnostic features (aggregation, color, secondary carbonate accumulation) and now key out as Kastanozem, Phaeozem or Regosol.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"40 ","pages":"Article e00920"},"PeriodicalIF":3.1,"publicationDate":"2025-01-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144466","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Estimation and mapping of soil pH in urban landscapes","authors":"Azamat Suleymanov ,&nbsp;Evgeny Abakumov ,&nbsp;Vyacheslav Polyakov ,&nbsp;Alexander Kozlov ,&nbsp;Nicolas P.A. Saby ,&nbsp;Petr Kuzmenko ,&nbsp;Salavat Telyagissov ,&nbsp;João Augusto Coblinski","doi":"10.1016/j.geodrs.2025.e00919","DOIUrl":"10.1016/j.geodrs.2025.e00919","url":null,"abstract":"<div><div>Despite their significance in understanding soil ecology and health, there is a scarcity of studies on soil modelling in urbanized landscapes. In this study, we evaluated the performance of machine learning (ML) and hybrid techniques in predicting topsoil pH (0–20 cm) in the city of St. Petersburg (Russia). We used a dataset of 84 soil pH measurements and environmental covariates, including remote sensing data, relief and anthropogenic maps. We applied Random Forest (RF) and RF plus Residual Kriging (RFRK) approaches for digital mapping of pH values. The predictive performance of the models was assessed using several metrics, mean absolute error (MAE), including root mean squared error (RMSE), coefficient of determination (R²) and Nash–Sutcliffe model efficiency coefficient (NSE). We also evaluated the prediction uncertainty with the prediction interval coverage probability (PICP) and “Area of applicability” (AOA) approach. Our results showed the pH levels varied between 4.4 and 8.6 and were characterized by moderate spatial dependence. Both models demonstrated similar performance, whereas the RFRK model slightly outperformed the RF approach with prediction performance MAE = 0.50, RMSE = 0.58, R² = 0.63 and NSE = 0.47. The PICP suggested that the uncertainty associated with pH was underestimated, whereas almost all predicted areas were within the AOA. We found that remote sensing covariates (vegetation indices) were the most important predictors of soil pH. According to the generated maps, alkaline soils were mostly located in urbanized areas with dense buildings, whereas low pH values were observed in parks and open relatively undisturbed areas. Our findings highlight the potential of remote sensing data for digital mapping of soil pH in urban environments, typically characterized by higher complexity and heterogeneity.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"40 ","pages":"Article e00919"},"PeriodicalIF":3.1,"publicationDate":"2025-01-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144993","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Investigating soil properties influencing the depth and degree of lessivage in Florida soils using a random forest modeling approach","authors":"Daniel J. Colopietro ,&nbsp;Julio Pachon ,&nbsp;Allan Bacon","doi":"10.1016/j.geodrs.2025.e00916","DOIUrl":"10.1016/j.geodrs.2025.e00916","url":null,"abstract":"<div><div>The translocation of clay sized particles is an extensive soil process that occurs in over half of the total surface area covered by soil globally. However, investigations into lessivage are usually limited in extent and scale, and results from experimental data do not reflect natural conditions since control is exerted on various soil properties, such as particle size distributions, and clay mineralogy. Using the NCSS Soil Characterization Database and the USDA Soil Taxonomy definition for an argillic horizon, a random forest machine learning approach was used to investigate lessivage in Florida soils. Within the database, 395 soil profiles observed and described in Florida were identified to have an argillic horizon and lack the presence of a lithologic discontinuity. The coefficient of determination (<em>R</em>^<em>2</em>), and the root mean square error (RMSE) were used to estimate the performance of the random forest model. The validation results showed that the model for the depth of lessivage achieved an <em>R</em>^<em>2</em> of 0.59 ± 0.07 and an RMSE of 27.86 ± 2.62 cm and the model for the degree of lessivage achieved an <em>R</em>^<em>2</em> of 0.68 ± 0.14 and an RMSE of 5.91 ± 3.25. A variable importance analysis indicated that the concentration of OC, the CEC, and the total extractable bases in the eluvial zone were the dominant soil properties in predicting the depth of the argillic horizon. The response in the predicted depth to the argillic horizon was similar with each of the aforementioned correlated variables and indicative of the flocculating mechanism, whereby polyvalent cations anchor OM to particle surfaces which then enables particle bridging. Whereas, extractable acidity in the eluvial zone and sand concentration in the illuvial zone were the dominant soil properties in predicting the degree of lessivage. As extractable acidity in the eluvial zone increased, the degree of lessivage decreased which could be indicative of coagulation due to an increase in the activity of Al³⁺ and H⁺ ions. Another mechanism identified in clay immobilization in this study is the cessation of the wetting front as a result of the loss of energy. As the depth to gleying increased, the predicted depth to the argillic horizon increased and the degree of lessivage increased. However, based on the variable importance analysis, this mechanism was not determined to be dominant in Florida soils.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"40 ","pages":"Article e00916"},"PeriodicalIF":3.1,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144464","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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":"Tracking pedogenic carbonate formation and alkalinity migration in agricultural soils amended with crushed wollastonite ore – Evidence from field trials in Southwestern Ontario","authors":"Reza Khalidy,&nbsp;Fatima Haque,&nbsp;Yi Wai Chiang,&nbsp;Rafael M. Santos","doi":"10.1016/j.geodrs.2025.e00918","DOIUrl":"10.1016/j.geodrs.2025.e00918","url":null,"abstract":"<div><div>Considered a well-known carbon sequestration method, terrestrial enhanced rock weathering (ERW) involves the application of crushed silicate-bearing minerals to urban and agricultural soils. Once dissolved in a soil–water system, alkaline minerals adjust the pH in a range favorable for pedogenic carbonate formation and, hence, atmospheric carbon drawdown. As a fast-weathering Ca-rich mineral, wollastonite is recognized as a primary candidate for this process. Although previous studies have demonstrated the potential of wollastonite to sequester carbon in croplands, no study has investigated the fate of wollastonite over the vertical profile of soil. Furthermore, no studies have investigated changes in the elemental composition of soils due to wollastonite amendment at the field scale. The present study presents the results of multiyear sample collection from different layers (0–15, 15–30, and 30–60 cm) of agricultural soil amended with wollastonite in Woodstock, Ontario, Canada. The impact of initial soil pH on pedogenic carbonate formation was also investigated through the inclusion of two more field trials (Thorndale and Dawn-Euphemia, Ontario). The results indicated that wollastonite addition increased the inorganic carbon pool of the soil at a rate as fast as 0.55 t CO₂/(ha·month) at higher (20 t/ha) wollastonite dosages, and with efficiencies reaching up to 0.42 t CO₂/t wollastonite (as CO₃^2-). Elemental composition analyses (WDXRF) revealed increases in the Ca (0.05–0.32 %) and Mg (0.01–0.02 %) contents in the amended soils that either were inferior to the theoretical amendment change, suggesting migration of weathering products to deeper layers, or in some cases similar and thus correlating with pedogenic carbonate retention in surficial layers. The implications of composite sampling and year-over-year comparisons on the estimated uncertainty from statistical analysis (hierarchical permutation test of the Wilcoxon signed-rank test) is discussed. This study concludes that carbonate formation is not limited to surficial layers and that deeper layers also need to be taken into account when estimating carbon capture due to ERW practices.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"40 ","pages":"Article e00918"},"PeriodicalIF":3.1,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144992","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"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 effect on soil quality and its implication to soil carbon storage in Aleta Chuko, Ethiopia","authors":"Zenebe Shuite ,&nbsp;Ambachew Demessie ,&nbsp;Tesfaye Abebe","doi":"10.1016/j.geodrs.2025.e00917","DOIUrl":"10.1016/j.geodrs.2025.e00917","url":null,"abstract":"<div><div>Soil quality index (SQI) is a useful tool to identify soil productivity status and design management strategies. Land use (LU) and management conditions can affect the physico-chemical qualities of the soil which in turn influences the carbon storage ability of the soil. However, the effects of LU on soil quality and associated carbon storage are not well understood in the Aleta Chuko. Three transect lines were drawn based on spatial analogue design covering three LU types, 4 plots for each land use from individual transect, 12 plots per LU, a total of 36 plots, and then 108 soil samples (0–30 cm depth) were taken in three diagonal pits within 20 × 20 m. 19 soil physico-chemical and biological properties were evaluated for SQI, and 12 soil quality indicators were selected using principal component analysis. The results showed that soil physico-chemical and biological characteristics were better under Coffee-enset based agroforestry (CEA) than Chat mono-cropping (CM) and Eucalyptus woodlot (EW). CEA showed significantly higher macro aggregate ≥ 5 mm, steady infiltration rate, Av. P, Av. K, Ex. K, total N, CEC and MBC, but no significant difference was observed between CM and EW in these variables (p &lt; 0.05). SQI of CEA, CM and EW were 0.61, 0.53 and 0.50, respectively. The higher SQI in CEA was due to high MBC(586.3 μg g⁻¹ soil), litterfall, SOM (4.7 %) and low bulk density (BD, 0.87 g cm⁻³). Total soil organic carbon was significantly higher in CEA (35.2) &gt; CM (24.2) &gt; EW (19.4) g kg⁻¹ soil and the same is true for Mg²⁺ CEA (4.9), CM (3.9) and EW (2.7) meq 100 g⁻¹ (p &lt; 0.05). Multiple regression analysis on five (BD, CEC, MBC, Ex. Ca and macro aggregates) soil quality determinant variables predicting SOC showed that these variables have a significant effect on SOC (p &lt; 0.001). Specifically, BD and MBC were significant negatively and positively predicting variables of SOC, respectively (p &lt; 0.001). This study suggests that LU practice and management variances over similar biophysical environments resulted in variations in soil physico-chemical, biological properties and the subsequent difference in SQI which in turn determine SOC storage capacity of the soil. Long-term effects of Eucalyptus and CM on soils should be a concern for degradation, although their short-term economic benefits are attractive.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"40 ","pages":"Article e00917"},"PeriodicalIF":3.1,"publicationDate":"2025-01-09","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144465","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Physically protected carbon stocks in a Brazilian Oxisol under homogeneous forest systems","authors":"Maicon dos Santos da Silva ,&nbsp;Patrícia Anjos Bittencourt Barreto-Garcia ,&nbsp;Paulo Henrique Marques Monroe ,&nbsp;Marcos Gervasio Pereira ,&nbsp;Luiz Alberto da Silva Rodrigues Pinto ,&nbsp;Marcio Renato Nunes","doi":"10.1016/j.geodrs.2024.e00915","DOIUrl":"10.1016/j.geodrs.2024.e00915","url":null,"abstract":"<div><div>The soil organic carbon (SOC) stock and its occlusion within aggregates is at the center of discussions regarding climate change and global warming, as it is one of the mechanisms capable of mitigating the effects of these phenomena. Despite this, studies on the topic in tropical soils under native forest species plantations are still scarce. Therefore, we developed this study asking how SOC and occluded carbon stocks in aggregates respond to homogeneous <em>Pterogyne nitens</em> (N-fixing species) and <em>Eucalyptus urophylla</em> plantations when compared to a native forest? The study was conducted in Oxisol under three forest systems: two homogeneous plantations (<em>P. nitens</em> and <em>E. urophylla</em>) and a native forest (NF), located in the State of Bahia, Brazil. Litter and soil samples were collected up to a meter deep. The soil samples were subjected to physical fractionation by wet sieving, obtaining three size classes of water-stable aggregates: macroaggegates (2000–250 μm), microaggregates (250–53 μm) silt+clay (&lt; 53 μm). The macroaggegates and microaggegates were sonicated to separate free and occluded particulate carbon. The carbon in whole soil and occluded in the aggregates were determined by the wet acidified oxidation method. The SOC stock (depth 100 cm) showed a reduction in the <em>P. nitens</em> plantation (123.1 Mg ha⁻¹) and maintenance in the <em>E. urophylla</em> plantation (194.4 Mg ha⁻¹) when compared to the NF (240.9 Mg ha⁻¹). Occluded carbon showed a lower value in plantations compared to NF, representing an average of 5.8 % of the SOC. The <em>P. nitens</em> plantation negatively impacted SOC stock as a result of lower litter amounts and higher litter decomposition rates. In contrast, the <em>E. urophylla</em> plantation maintained SOC stocks close to those found in the NF due to the large amounts of litter and its high recalcitrance. Both forest plantations affect carbon occlusion in the aggregates, and therefore the SOC is poorly protected physically.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"40 ","pages":"Article e00915"},"PeriodicalIF":3.1,"publicationDate":"2025-01-02","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144970","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Faster topsoil organic matter transformation accompanies long-term carbon preservation in virgin Chernozems","authors":"Alla Yu. Yurova ,&nbsp;M.A. Smirnova ,&nbsp;D.N. Kozlov ,&nbsp;D.R. Bardashev ,&nbsp;N.I. Lozbenev ,&nbsp;V.M. Stepanenko","doi":"10.1016/j.geodrs.2024.e00914","DOIUrl":"10.1016/j.geodrs.2024.e00914","url":null,"abstract":"<div><div>This study examines soil organic carbon (SOC) dynamics in different soil types across a micro-topographical gradient, focusing on topsoil SOC stabilization and turnover rates in virgin Chernozems. The thermodynamic origin of differences in SOC decomposability (henceforth referred to as “quality”, or “q”) between soil types is explained using a Q model that treats quality as a continuous variable rather than assuming the presence of discrete SOC pools. The model's calibration is focused on enabling effective assessment of overall SOC stocks in the topsoil (the topmost 10 cm) and the total carbon stock in the uppermost 50 cm while using radiocarbon turnover rates as secondary constraints that may be needed due to limited data availability. The SOC turnover time in the topsoil determined by modeling the SOC quality distribution function was shown to agree well with empirical findings from similar study sites, indicating that SOC turnover times are around 6–10 years in surface layers but millennia in deeper layers. This reinforces the importance of distinguishing between topsoil and subsoil carbon stocks and their respective stabilization mechanisms in Chernozems. The analysis also highlights the influence of soil temperature and moisture conditions on soil organic carbon (SOC) dynamics: high topsoil moisture levels due to lateral water inputs increase SOC stabilization and thus reduce q, so wetter sites have enhanced carbon stocks. This outcome aligns with existing theories of humification in which water availability emerges as a crucial factor influencing SOC preservation and stabilization. Wetter soils also exhibit reduced decomposition due to lower temperature. This interplay between moisture, temperature, and microbial respiration rates necessitates a reevaluation of conventional beliefs about the behavior of SOC in different water regimes that stress the impact of moisture on soil respiration but not SOC stabilization. These findings also highlight the need to account for microtopographic variation, especially in semi-arid regions, in soil management programs seeking to optimize SOC retention and overall soil health. The insights into SOC dynamics presented here will be valuable for improving soil management strategies to enhance carbon sequestration in various soil types under changing climatic conditions.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"40 ","pages":"Article e00914"},"PeriodicalIF":3.1,"publicationDate":"2024-12-28","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144969","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}

{"title":"Carbon stock, subsurface characteristics and accommodation settings of sub-tropical peatland Histosols, K'gari, Queensland Australia","authors":"Gareth Chalmers ,&nbsp;Zeinab Ghasemzadeh ,&nbsp;David Chittleborough ,&nbsp;Allen Gontz ,&nbsp;Iroshaka Gregory Cooray ,&nbsp;Catherine Yule ,&nbsp;Darshanaa Chellaiah ,&nbsp;Adrian McCallum","doi":"10.1016/j.geodrs.2024.e00913","DOIUrl":"10.1016/j.geodrs.2024.e00913","url":null,"abstract":"<div><div>Whereas temperate and tropical peatlands have been extensively studied, much less is known about the age, formation history, carbon stock and soil characteristics of subtropical peatlands. Here we investigate the organic carbon density or stock and soil characteristics of three peatlands of K'gari (Fraser Island), Queensland, Australia. The <em>Empodisma minus</em> -dominated peatlands are unique to the subtropics and their bulk density, pH, oxidation-reduction potential, carbon percentages and carbon stocks were compared to other <em>Empodisma</em> sp. peatlands in temperate and montane-alpine climates as well as global peatland estimates. A good agreement occurs between the elemental analyser (LECO) derived carbon percentages and the estimations made by loss-of-ignition-derived carbon percentages using <span><span>Farmer et al. (2014)</span></span> conversion factor. Carbon stock estimation ranges between 381.2 and 1665.5 Mg C ha⁻¹ for the total peat depth and ranges between 444.0 and 1189.7 Mg C ha⁻¹ on a per metre basis. The carbon stock average for the Moon Point and Dilli Swamp peatlands is comparable to global peatland estimates with the Red Lagoon peatland is lower than the average. All three peatlands have a higher average carbon stock than other <em>Empodisma</em>-dominated peatlands in temperate and montane-alpine climates.</div><div>The three peatland sites chosen are within different morphosequences that range in age between Holocene, 7.8 to 132 ka and 132–263 ka. The Moon Point peatland (Holocene; &lt; 11,700 BP) has a higher bulk density, lower moisture content and higher degree of humification compared to the other morphosequence areas. The difference in peat characteristics is not due to the morphosequence, as the climate changed approximately 6000 to 5000 years BP to be more favourable for peat accumulation across south-east Queensland. However, we suspect the older morphosequence (i.e., Yankee Jack) as well as the Holocene coastal sediment setting, due to their lower topography reduces the groundwater level and the accommodation space for peats to accumulate. The lower accommodation setting limits the peat thickness, increases the number of hiatuses and is susceptible to more peat fires. This study shows the K'gari peatlands are significant carbon sinks and careful management is needed to ensure they do not become carbon emitters as climate continues to change.</div></div>","PeriodicalId":56001,"journal":{"name":"Geoderma Regional","volume":"40 ","pages":"Article e00913"},"PeriodicalIF":3.1,"publicationDate":"2024-12-27","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"143144966","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":2,"RegionCategory":"农林科学","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"OA","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}