Perennial cropping systems hold great potential to enhance soil organic carbon (SOC) stocks and contribute to climate change mitigation. However, the effects of perennial crops on SOC fractions with different stabilities remain poorly understood. Particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) are considered to have different formation mechanisms and different stabilities. Plant- and microbial-derived carbon (C) are the main origins of SOC, yet their relative contributions to POC and MAOC remain unclear. Here, based on an 11-year experiment, we compared two perennial cropping systems (festulolium and grass-clover) with an annual cropping system (maize), to investigate their effects on soil POC and MAOC, and quantify the contribution of plant- and microbial-derived C to these two soil C fractions using lignin phenols and amino sugars as biomarkers.
The soil of the two perennials had higher POC and MAOC than maize at 0–20 cm soil depth, with higher proportions of POC in SOC. The higher POC of the two perennials was linked to their significantly higher fungal and bacterial necromass C in POC. Total microbial necromass C accounted for only 29% of POC and 36% of MAOC at 0–20 cm across all systems, suggesting that plant-derived C dominates these two C pools. However, no significant differences were detected in the lignin phenols content in POC and MAOC at 0–20 cm. Our results challenge the conventional assumption that microbial necromass C dominates MAOC, highlighting the role of plant-derived C in POC and MAOC, which could have a greater influence on soil C sequestration in climates with low mean annual temperature than previously assumed. Given that only two biomarkers were used, interpretations should not be extrapolated beyond their analytical scope.
{"title":"Microbial and plant-derived carbon contributions to particulate and mineral-associated organic carbon in perennial and annual cropping systems","authors":"Yiwei Shang , Zhi Liang , Imran Ahammad Siddique , Michaela Dippold , Diego Abalos , Jørgen Eivind Olesen","doi":"10.1016/j.geoderma.2026.117688","DOIUrl":"10.1016/j.geoderma.2026.117688","url":null,"abstract":"<div><div>Perennial cropping systems hold great potential to enhance soil organic carbon (SOC) stocks and contribute to climate change mitigation. However, the effects of perennial crops on SOC fractions with different stabilities remain poorly understood. Particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) are considered to have different formation mechanisms and different stabilities. Plant- and microbial-derived carbon (C) are the main origins of SOC, yet their relative contributions to POC and MAOC remain unclear. Here, based on an 11-year experiment, we compared two perennial cropping systems (festulolium and grass-clover) with an annual cropping system (maize), to investigate their effects on soil POC and MAOC, and quantify the contribution of plant- and microbial-derived C to these two soil C fractions using lignin phenols and amino sugars as biomarkers.</div><div>The soil of the two perennials had higher POC and MAOC than maize at 0–20 cm soil depth, with higher proportions of POC in SOC. The higher POC of the two perennials was linked to their significantly higher fungal and bacterial necromass C in POC. Total microbial necromass C accounted for only 29% of POC and 36% of MAOC at 0–20 cm across all systems, suggesting that plant-derived C dominates these two C pools. However, no significant differences were detected in the lignin phenols content in POC and MAOC at 0–20 cm. Our results challenge the conventional assumption that microbial necromass C dominates MAOC, highlighting the role of plant-derived C in POC and MAOC, which could have a greater influence on soil C sequestration in climates with low mean annual temperature than previously assumed. Given that only two biomarkers were used, interpretations should not be extrapolated beyond their analytical scope.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"466 ","pages":"Article 117688"},"PeriodicalIF":6.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145974843","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}
Pub Date : 2026-02-01Epub Date: 2026-01-30DOI: 10.1016/j.geoderma.2026.117707
Yanqing Yang , Wei Zhao , Tao Ding , Jiujiang Wu , Junli Zhao
Soil moisture (SM) conditions are closely linked to water availability, energy balance, and ecosystem processes, highlighting the importance of accurate SM data for hydrological modeling and environmental monitoring. Passive microwave products offer large-scale SM estimates, but their validation in mountainous areas remains difficult due to sparse in situ data and complex terrain. This study systematically evaluated three global passive microwave soil moisture products—SMAP, SMOS, and AMSR2—across mountainous regions by integrating in situ observations from the International Soil Moisture Network (ISMN) with the Extended Triple Collocation (ETC) method. Results indicated that SMAP and SMOS outperformed AMSR2 in both in situ and ETC-based evaluations, with higher median correlation coefficients (0.95 for SMAP, 0.84 for SMOS) and lower RMSEs (0.026 and 0.048 m3/m3, respectively). In the Rocky Mountains, where station density is highest, over 86% of sites showed consistent product rankings between in situ and ETC results, confirming the reliability of ETC in data-scarce areas. Further analysis revealed contrasting environmental controls: SMAP’s error increased with slope and vegetation density, while its sensitivity increased with elevation and surface roughness. SMOS showed more stable performance across gradients, whereas AMSR2 was more affected by terrain and vegetation complexity. These findings clarify uncertainty patterns and environmental controls on passive microwave soil moisture retrievals in mountainous regions, and provide insights for product selection, algorithm improvement, and data fusion in hydrological and ecological applications.
{"title":"Assessing global passive microwave soil moisture retrievals in mountainous terrain: insights from in situ validation and extended triple collocation","authors":"Yanqing Yang , Wei Zhao , Tao Ding , Jiujiang Wu , Junli Zhao","doi":"10.1016/j.geoderma.2026.117707","DOIUrl":"10.1016/j.geoderma.2026.117707","url":null,"abstract":"<div><div>Soil moisture (SM) conditions are closely linked to water availability, energy balance, and ecosystem processes, highlighting the importance of accurate SM data for hydrological modeling and environmental monitoring. Passive microwave products offer large-scale SM estimates, but their validation in mountainous areas remains difficult due to sparse in situ data and complex terrain. This study systematically evaluated three global passive microwave soil moisture products—SMAP, SMOS, and AMSR2—across mountainous regions by integrating in situ observations from the International Soil Moisture Network (ISMN) with the Extended Triple Collocation (ETC) method. Results indicated that SMAP and SMOS outperformed AMSR2 in both in situ and ETC-based evaluations, with higher median correlation coefficients (0.95 for SMAP, 0.84 for SMOS) and lower RMSEs (0.026 and 0.048 m3/m3, respectively). In the Rocky Mountains, where station density is highest, over 86% of sites showed consistent product rankings between in situ and ETC results, confirming the reliability of ETC in data-scarce areas. Further analysis revealed contrasting environmental controls: SMAP’s error increased with slope and vegetation density, while its sensitivity increased with elevation and surface roughness. SMOS showed more stable performance across gradients, whereas AMSR2 was more affected by terrain and vegetation complexity. These findings clarify uncertainty patterns and environmental controls on passive microwave soil moisture retrievals in mountainous regions, and provide insights for product selection, algorithm improvement, and data fusion in hydrological and ecological applications.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"466 ","pages":"Article 117707"},"PeriodicalIF":6.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146074611","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}
Pub Date : 2026-02-01Epub Date: 2026-01-24DOI: 10.1016/j.geoderma.2026.117700
Gaus Azam , Md. Shahinur Rahman , Craig Scanlan , Md. Hasinur Rahman , Ross Gazey , Edward G. Barrett-Lennard , Kanch Wickramarachchi , Bob Nixon , Chris Gazey
The co-occurrence of subsoil compaction and acidity commonly decreases the yield and water use efficiency (WUE) of agricultural crops around the world, yet the benefits of the complete amelioration of these constraints on yield and WUE remain unclear. We conducted a long-term field experiment in Western Australia (WA) to evaluate the effects of the complete removal of subsoil compaction and acidity through soil profile re-engineering — involving soil removal, replacement, and lime incorporation — on root architecture, yield, and WUE in wheat (Triticum aestivum L.) and barley (Hordeum vulgare L.). Treatments included an untreated control, and soil loosening to 0.45 m depth and lime incorporation at three depths combined with loosening (0.45 m). Results showed that the improvements in soil conditions through soil re-engineering were maintained for seven years. In the control, the roots of cereal crops were confined to the top 0.2–0.3 m of soil, while soil re-engineering tripled the rooting depth and created a more uniform root distribution. The removal of compaction improved wheat root architecture but did not affect barley. These improvements increased yield and WUE up to 3.7-fold, and the benefits occurred in every season. In the best treatment, wheat yield ranged from 945 to 4164 kg ha−1 and WUE from 16.9 to 33.3 kg mm−1, compared with 252–1722 kg ha−1 and 6.5–13.0 kg mm−1 in the control. Moreover, the best treatments substantially exceeded the expected yields of crops grown under comparable climatic conditions, based on two independent published datasets from WA and southern Australia. Our findings show that soil re-engineering can sustainably improve yield and WUE on coarse-textured sandy soils with multiple subsoil constraints for the long-term in water-limited environments. While this approach may not be directly scalable or economically feasible, it provides a foundation for the development of more comprehensive tillage machinery suitable for large scale soil profile re-engineering.
在世界范围内，底土压实和酸性的共同存在通常会降低农作物的产量和水分利用效率（WUE），但完全改善这些对产量和水分利用效率的限制所带来的好处尚不清楚。我们在西澳大利亚（WA）进行了一项长期的田间试验，以评估通过土壤剖面再造（包括土壤去除、置换和石灰加入）彻底去除地下土壤压实和酸性对小麦（Triticum aestivum L.）和大麦（Hordeum vulgare L.）根系构型、产量和水分利用效率的影响。处理包括未经处理的对照，土壤松动至0.45 m深度，在三个深度加入石灰并松动（0.45 m）。结果表明，土壤再造对土壤条件的改善持续了7年。在对照中，谷类作物的根系被限制在土壤顶部0.2 ~ 0.3 m，而土壤再造使根系深度增加了两倍，根系分布更加均匀。消除压实改善了小麦的根系结构，但对大麦没有影响。这些改进使产量和水分利用效率提高了3.7倍，并且每个季节都有效益。在最佳处理下，小麦产量为945 ~ 4164 kg ha - 1，水分利用效率为16.9 ~ 33.3 kg mm - 1，而对照为252 ~ 1722 kg ha - 1和6.5 ~ 13.0 kg mm - 1。此外，根据西澳和南澳大利亚两个独立公布的数据集，在可比气候条件下，最佳处理大大超过了作物的预期产量。研究结果表明，在缺水环境下，土壤再造可以长期持续提高具有多重底土约束的粗质沙质土壤的产量和水分利用效率。虽然这种方法可能无法直接扩展或在经济上可行，但它为开发适合大规模土壤剖面再造的更全面的耕作机械提供了基础。
{"title":"Deep amelioration of compaction and acidity doubled the water use efficiency of cereal crops on a sandy soil in a long-term experiment in a water-limited environment","authors":"Gaus Azam , Md. Shahinur Rahman , Craig Scanlan , Md. Hasinur Rahman , Ross Gazey , Edward G. Barrett-Lennard , Kanch Wickramarachchi , Bob Nixon , Chris Gazey","doi":"10.1016/j.geoderma.2026.117700","DOIUrl":"10.1016/j.geoderma.2026.117700","url":null,"abstract":"<div><div>The co-occurrence of subsoil compaction and acidity commonly decreases the yield and water use efficiency (WUE) of agricultural crops around the world, yet the benefits of the complete amelioration of these constraints on yield and WUE remain unclear. We conducted a long-term field experiment in Western Australia (WA) to evaluate the effects of the complete removal of subsoil compaction and acidity through soil profile re-engineering — involving soil removal, replacement, and lime incorporation — on root architecture, yield, and WUE in wheat (<em>Triticum aestivum</em> L.) and barley (<em>Hordeum vulgare</em> L.). Treatments included an untreated control, and soil loosening to 0.45 m depth and lime incorporation at three depths combined with loosening (0.45 m). Results showed that the improvements in soil conditions through soil re-engineering were maintained for seven years. In the control, the roots of cereal crops were confined to the top 0.2–0.3 m of soil, while soil re-engineering tripled the rooting depth and created a more uniform root distribution. The removal of compaction improved wheat root architecture but did not affect barley. These improvements increased yield and WUE up to 3.7-fold, and the benefits occurred in every season. In the best treatment, wheat yield ranged from 945 to 4164 kg ha<sup>−1</sup> and WUE from 16.9 to 33.3 kg mm<sup>−1</sup>, compared with 252–1722 kg ha<sup>−1</sup> and 6.5–13.0 kg mm<sup>−1</sup> in the control. Moreover, the best treatments substantially exceeded the expected yields of crops grown under comparable climatic conditions, based on two independent published datasets from WA and southern Australia. Our findings show that soil re-engineering can sustainably improve yield and WUE on coarse-textured sandy soils with multiple subsoil constraints for the long-term in water-limited environments. While this approach may not be directly scalable or economically feasible, it provides a foundation for the development of more comprehensive tillage machinery suitable for large scale soil profile re-engineering.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"466 ","pages":"Article 117700"},"PeriodicalIF":6.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146048419","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}
Pub Date : 2026-02-01Epub Date: 2026-02-04DOI: 10.1016/j.geoderma.2026.117711
Wangzun Chen , Yanlong Li , Yi Peng , Letian Wang , Gu Feng
Fertilization alters soil stoichiometric ratios, shaping microbial processes and phosphorus (P) dynamics, yet the underlying mechanisms remain poorly understood. Here, we conducted a three-year maize field experiment on the North China Plain, to test how P-based manure amendments modified soil C:P ratio, intensified microbially mediated soil P mobilization and turnover processes, and improved crop P uptake and yield. There were four treatments as follows: P0, no P fertilizer; P1, 39.27 kg ha−1 of chemical P; LCP, with a total P input of 39.27 kg P ha−1, input 0.76 t ha−1 manure C; and HCP, with a total P input of 39.27 kg P ha−1, input 1.53 t ha−1 manure C. Our results suggested that manure C inputs significantly increased the content of soil dissolved organic carbon (DOC) and induced a shift in microbial community composition from oligotrophic (Acidobacteria) to copiotrophic taxa (Proteobacteria, Bacteroidetes, Myxococcota), accompanied by increased microbial biomass P. Manure amendment significantly raised the soil C:P ratio, but the microbial C:P ratio remained relatively stable across treatments. The induced C:P imbalance intensified microbial P limitation, exerting selective pressure on soil microbes preferential investment in P mobilization. Through the coordinated regulation of microbial community composition and function, manure amendment enhanced the bioavailable P pool and increased plant P acquisition. By increasing soil C:P ratios relative to full chemical fertilization, P-based manure amendment increased maize yield by 12%, improved P fertilizer recovery efficiency from 81.34% to 97.06%, enhanced P fertilizer utilization efficiency from 22.01% to 36.69%, and reduced soil P accumulation from 7.35 to 1.15 kg P ha−1 year−1. These findings suggest that manure-induced stoichiometric imbalance triggers a priming effect on indigenous microbial P mobilization, providing an ecologically intensive pathway to enhance fertilizer P use efficiency, reduce environmental P loading, and improve crop productivity.
施肥改变土壤化学计量比，塑造微生物过程和磷(P)动态，但潜在的机制仍然知之甚少。本研究在华北平原进行了为期3年的玉米田试验，研究了磷基肥料改剂剂对土壤碳磷比的影响，增强了微生物介导的土壤磷的动员和周转过程，提高了作物对磷的吸收和产量。4个处理分别为：P0，不施磷肥；P1, 39.27 kg ha - 1化学P；LCP，总磷投入量为39.27 kg P ha−1，粪肥C投入量为0.76 t ha−1；结果表明，有机肥C显著提高了土壤溶解有机碳（DOC）含量，并导致微生物群落组成由贫营养（酸杆菌）向富营养（变形菌门、拟杆菌门、粘球菌门）转变，同时显著提高了微生物生物量P。但各处理间微生物C:P比值保持相对稳定。碳磷失衡加剧了微生物对磷的限制，对土壤微生物优先投入磷动员施加了选择压力。通过对微生物群落组成和功能的协调调节，肥料改良增加了生物有效磷库，增加了植物磷的获取。通过提高土壤C:P比，磷肥改良使玉米产量提高了12%，磷肥回收率从81.34%提高到97.06%，磷肥利用率从22.01%提高到36.69%，土壤磷素积累量从7.35 kg P ha - 1年- 1减少到1.15 kg P ha - 1年- 1。这些结果表明，粪便诱导的化学计量失衡触发了本地微生物磷动员的启动效应，为提高肥料磷利用效率、减少环境磷负荷和提高作物生产力提供了生态集约途径。
{"title":"Carbon-phosphorus stoichiometric imbalance induced by manure amendment enhances microbial phosphorus mobilization and crop phosphorus uptake","authors":"Wangzun Chen , Yanlong Li , Yi Peng , Letian Wang , Gu Feng","doi":"10.1016/j.geoderma.2026.117711","DOIUrl":"10.1016/j.geoderma.2026.117711","url":null,"abstract":"<div><div>Fertilization alters soil stoichiometric ratios, shaping microbial processes and phosphorus (P) dynamics, yet the underlying mechanisms remain poorly understood. Here, we conducted a three-year maize field experiment on the North China Plain, to test how P-based manure amendments modified soil C:P ratio, intensified microbially mediated soil P mobilization and turnover processes, and improved crop P uptake and yield. There were four treatments as follows: P0, no P fertilizer; P1, 39.27 kg ha<sup>−1</sup> of chemical P; LCP, with a total P input of 39.27 kg P ha<sup>−1</sup>, input 0.76 t ha<sup>−1</sup> manure C; and HCP, with a total P input of 39.27 kg P ha<sup>−1</sup>, input 1.53 t ha<sup>−1</sup> manure C. Our results suggested that manure C inputs significantly increased the content of soil dissolved organic carbon (DOC) and induced a shift in microbial community composition from oligotrophic (Acidobacteria) to copiotrophic taxa (Proteobacteria, Bacteroidetes, Myxococcota), accompanied by increased microbial biomass P. Manure amendment significantly raised the soil C:P ratio, but the microbial C:P ratio remained relatively stable across treatments. The induced C:P imbalance intensified microbial P limitation, exerting selective pressure on soil microbes preferential investment in P mobilization. Through the coordinated regulation of microbial community composition and function, manure amendment enhanced the bioavailable P pool and increased plant P acquisition. By increasing soil C:P ratios relative to full chemical fertilization, P-based manure amendment increased maize yield by 12%, improved P fertilizer recovery efficiency from 81.34% to 97.06%, enhanced P fertilizer utilization efficiency from 22.01% to 36.69%, and reduced soil P accumulation from 7.35 to 1.15 kg P ha<sup>−1</sup> year<sup>−1</sup>. These findings suggest that manure-induced stoichiometric imbalance triggers a priming effect on indigenous microbial P mobilization, providing an ecologically intensive pathway to enhance fertilizer P use efficiency, reduce environmental P loading, and improve crop productivity.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"466 ","pages":"Article 117711"},"PeriodicalIF":6.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146134163","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}
Pub Date : 2026-02-01Epub Date: 2026-02-02DOI: 10.1016/j.geoderma.2026.117702
Jordon Wade , Teal M. Potter , Andrew J. Margenot
Structural equation modeling (SEM) is a set of approaches that have seen exponential usage in the soil sciences as well as the related fields of agriculture and biogeochemistry. When correctly used and interpreted, SEM can be a powerful and flexible tool to test complex hypotheses on causality. However, the recent explosion of SEM usage in the soil sciences facilitated by user-friendly statistical programs has not been fully met by statistical expertise of users, reviewers and editors, ultimately leading to widespread contamination of the literature with inappropriate modeling and inflated or unfounded causal claims. The rise of such “SEM slop” poses a serious risk of an unreliable knowledge base and also undermines efforts and standards on what constitutes causality in the soil sciences. To address this, we diagnose major pitfalls in SEM, with an eye towards considerations specific to soil sciences, categorizable as three types: (1) Causal claims, including not satisfying causal criteria, lack of justified a priori models, not considering counterfactuals, and unqualified causal language; (2) Experimental design, including use in randomized complete block designs without complete pooling or multi-level models, inappropriate data type (e.g., ontological misalignment), and insufficient sample size; and, (3) Assessing the model, including incomplete or inappropriate model evaluation, non-qualified use of modification indices, and lack of robustness tests. There is a dual imperative for users as well as reviewers and editors to better implement and evaluate SEMs and claims of causality made with SEMs. To support this, we offer best practices and practical considerations on these three major pitfalls. These best practices will help SEM be appropriately employed as a powerful, nuanced statistical tool that benefits the soil science community.
{"title":"Commentary: Structural equation models and causal claims in soil science and biogeochemistry – An equation-free “how to”","authors":"Jordon Wade , Teal M. Potter , Andrew J. Margenot","doi":"10.1016/j.geoderma.2026.117702","DOIUrl":"10.1016/j.geoderma.2026.117702","url":null,"abstract":"<div><div>Structural equation modeling (SEM) is a set of approaches that have seen exponential usage in the soil sciences as well as the related fields of agriculture and biogeochemistry. When correctly used and interpreted, SEM can be a powerful and flexible tool to test complex hypotheses on causality. However, the recent explosion of SEM usage in the soil sciences facilitated by user-friendly statistical programs has not been fully met by statistical expertise of users, reviewers and editors, ultimately leading to widespread contamination of the literature with inappropriate modeling and inflated or unfounded causal claims. The rise of such “SEM slop” poses a serious risk of an unreliable knowledge base and also undermines efforts and standards on what constitutes causality in the soil sciences. To address this, we diagnose major pitfalls in SEM, with an eye towards considerations specific to soil sciences, categorizable as three types: (1) <em>Causal claims</em>, including not satisfying causal criteria, lack of justified a priori models, not considering counterfactuals, and unqualified causal language; (2) <em>Experimental design</em>, including use in randomized complete block designs without complete pooling or multi-level models, inappropriate data type (e.g., ontological misalignment), and insufficient sample size; and, (3) <em>Assessing the model</em>, including incomplete or inappropriate model evaluation, non-qualified use of modification indices, and lack of robustness tests. There is a dual imperative for users as well as reviewers and editors to better implement and evaluate SEMs <em>and</em> claims of causality made with SEMs. To support this, we offer best practices and practical considerations on these three major pitfalls. These best practices will help SEM be appropriately employed as a powerful, nuanced statistical tool that benefits the soil science community.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"466 ","pages":"Article 117702"},"PeriodicalIF":6.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146110572","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}
Pub Date : 2026-02-01Epub Date: 2026-01-22DOI: 10.1016/j.geoderma.2026.117698
Andre Velescu , Jürgen Homeier , Carlos Iván Espinosa , Wolfgang Wilcke
The tropical montane forests in southern Ecuador are subject to rising nitrogen (N), low phosphorus (P), and episodic calcium (Ca) deposition. To investigate the response of the vegetation, soil organic layer and mineral soil to 0.3 m depth to increased nutrient inputs, we initiated in 2008 an interdisciplinary Nutrient Manipulation Experiment (NUMEX) at 2000 m a.s.l. We have applied N as urea at 50 kg ha−1 year−1, P as NaH2PO4 at 10 kg ha−1 year−1, combined N and P at 50 + 10 kg ha−1 year−1, and Ca (as CaCl2), at 10 kg ha−1 year−1. From 2008 to 2012, we set up annual budgets by calculating net fluxes of N, P, Ca and Na for the canopy, the organic layer and the mineral soil and determined δ15N values in the foliage of the four most abundant tree species, litterfall and organic layer. The addition of P and N + P increased P leaching from the canopy, suggesting a reduced retention of deposited P by canopy organisms. All added nutrients were largely retained in the soil organic layer and tightly cycled between the organic layer and the vegetation via litterfall and throughfall. The small leaching losses of N, P, Ca and Na from the organic layer were retained in the upper mineral soil. The retention of the added nutrients in the ecosystem indicated a strong nutrient demand. Nevertheless, the 15N enrichment in the organic layer was an early indicator of beginning N losses from the ecosystem by leaching and volatilization, which could not yet be detected by our flux-based budgeting approach.
厄瓜多尔南部的热带山地森林受到氮(N)上升、磷(P)低和偶发性钙（Ca）沉积的影响。为了研究0.3 m以下植被、土壤有机层和矿质土对增加养分投入的响应，我们于2008年启动了一项2000 m a.s.l的跨学科养分调控实验（NUMEX）。我们在50 kg ha−1年−1施用N作为尿素，在10 kg ha−1年−1施用P作为NaH2PO4，在50 + 10 kg ha−1年−1施用N和P，在10 kg ha−1年−1施用Ca（作为CaCl2）。2008 - 2012年，通过计算林冠层、有机层和矿质土N、P、Ca、Na的净通量，建立了林冠层、有机层和矿质土的年度收支，并测定了4种最丰富树种、凋落物和有机层的叶片δ15N值。P和N + P的添加增加了冠层的磷淋溶，表明冠层生物对沉积磷的保留减少。所有添加的养分大部分保留在土壤有机层中，并通过凋落物和穿透物在有机层和植被之间紧密循环。有机层中N、P、Ca和Na的少量淋失被保留在上层矿质土中。添加的营养物质在生态系统中的保留表明了强烈的营养需求。然而，有机层中的15N富集是生态系统通过淋滤和挥发开始的N损失的早期指标，这还不能通过基于通量的预算方法检测到。
{"title":"Response of element cycling and budgets to nutrient additions in a tropical montane forest of Ecuador","authors":"Andre Velescu , Jürgen Homeier , Carlos Iván Espinosa , Wolfgang Wilcke","doi":"10.1016/j.geoderma.2026.117698","DOIUrl":"10.1016/j.geoderma.2026.117698","url":null,"abstract":"<div><div>The tropical montane forests in southern Ecuador are subject to rising nitrogen (N), low phosphorus (P), and episodic calcium (Ca) deposition. To investigate the response of the vegetation, soil organic layer and mineral soil to 0.3 m depth to increased nutrient inputs, we initiated in 2008 an interdisciplinary Nutrient Manipulation Experiment (NUMEX) at 2000 m a.s.l. We have applied N as urea at 50 kg ha<sup>−1</sup> year<sup>−1</sup>, P as NaH<sub>2</sub>PO<sub>4</sub> at 10 kg ha<sup>−1</sup> year<sup>−1</sup>, combined N and P at 50 + 10 kg ha<sup>−1</sup> year<sup>−1</sup>, and Ca (as CaCl<sub>2</sub>), at 10 kg ha<sup>−1</sup> year<sup>−1</sup>. From 2008 to 2012, we set up annual budgets by calculating net fluxes of N, P, Ca and Na for the canopy, the organic layer and the mineral soil and determined δ<sup>15</sup>N values in the foliage of the four most abundant tree species, litterfall and organic layer. The addition of P and N + P increased P leaching from the canopy, suggesting a reduced retention of deposited P by canopy organisms. All added nutrients were largely retained in the soil organic layer and tightly cycled between the organic layer and the vegetation via litterfall and throughfall. The small leaching losses of N, P, Ca and Na from the organic layer were retained in the upper mineral soil. The retention of the added nutrients in the ecosystem indicated a strong nutrient demand. Nevertheless, the <sup>15</sup>N enrichment in the organic layer was an early indicator of beginning N losses from the ecosystem by leaching and volatilization, which could not yet be detected by our flux-based budgeting approach.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"466 ","pages":"Article 117698"},"PeriodicalIF":6.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146033237","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}
Pub Date : 2026-02-01Epub Date: 2026-01-19DOI: 10.1016/j.geoderma.2026.117685
Adrian F. Florea , Dominik H. Zak , Rasmus Jes Petersen , Carolin L. Dreher , Andreas Kappler , Hans Christian B. Hansen
Drainage and cultivation of organic lowland peat soils have profoundly altered their hydrological and biogeochemical functions, increasing greenhouse gas emissions and phosphorus (P) mobilization due to enhanced mineralization. Rewetting is increasingly promoted to mitigate these impacts. However, intensive agricultural use has led to P accumulation, primarily bound to Fe(III)(oxyhydr)oxide minerals, raising the risk of P release under anoxic conditions and challenging the restoration of these systems as nutrient sinks. Predicting P release remains difficult due to complex interactions, including P re-sorption to metal oxides with remaining P binding places and precipitation as Fe(II) or Ca phosphates such as vivianite and hydroxyapatite.
This study investigates Fe(III)(oxyhydr)oxide reduction extent and associated P mobilization in two contrasting Danish lowland peatlands over 24 months: the acidic Vejrumbro and neutral-alkaline Løvenborg. Oxalate-extractable Fe, Al, and P (Feox, Alox, Pox) differed substantially between sites. Løvenborg exhibited higher Feox (198–241 mmol kg−1) and Alox (41–49 mmol kg−1) than Vejrumbro (Feox: 27–122 mmol kg−1; Alox: 4.5–40 mmol kg−1), resulting in greater P sorption capacity (PSC: 239–287 vs. 44–155 mmol kg−1). The degree of P saturation (DPS) remained low at both sites (<10%).
Under winter or wet field conditions, Fe(III)(oxyhydr)oxide reduction extent reached up to 100%, indicating complete dissolution of the Feox pool. Despite extensive reduction, soluble P (PSol) remained low in Løvenborg (≤0.3 mg L−1), whereas Vejrumbro exhibited high PSol concentrations (up to 4.7 mg L−1). Powder X-ray diffraction and Mössbauer spectroscopy confirmed vivianite formation in Løvenborg, demonstrating P immobilization via precipitation. Moreover, in Løvenborg, the saturation index calculated using the geochemical model Minteq showed values between 2.5 and 4.2 with respect to vivianite supersaturation, while for Ca-P precipitates such as hydroxyapatite, Løvenborg soils show near equilibrium (0.09) to slight undersaturation (−1.8). In contrast, P retention in Vejrumbro was mainly through adsorption onto residual Fe and Al oxide minerals.
These results indicate that P release risk models must go beyond re-adsorption, and include precipitation pathways, which depend on metal-oxide content, cation availability (e.g., Ca2+, Fe2+), pH, alkalinity, and the extent of Fe(III) reduction. Incorporating key geochemical indicators—such as pH, sorption capacity, calcium content, Fe(III) reduction extent, and alkalinity may lead to better classification of peat soils and guide rewetting strategies safeguarding minimal P release.
有机低地泥炭土的排水和耕作深刻地改变了其水文和生物地球化学功能，增加了温室气体排放和磷(P)的动员。为了减轻这些影响，越来越多的人提倡重新润湿。然而，集约化农业利用导致了磷的积累，主要与Fe(III)（氧合）氧化物矿物结合，增加了缺氧条件下磷释放的风险，并挑战了这些系统作为养分汇的恢复。由于复杂的相互作用，预测磷的释放仍然很困难，包括磷再吸附到金属氧化物上，剩余的P结合位置和沉淀为铁（II）或钙磷酸盐，如橄榄石和羟基磷灰石。本研究调查了丹麦两个不同的低地泥炭地（酸性的Vejrumbro和中性碱性的Løvenborg）在24个月内的铁（III）（氧）氧化物还原程度和相关的磷动员。草酸盐可提取的Fe， Al和P （Feox, Alox, Pox）在不同位点之间差异很大。与Vejrumbro （Feox: 27-122 mmol kg - 1; Alox: 4.5-40 mmol kg - 1）相比，Løvenborg表现出更高的Feox （199 - 241 mmol kg - 1）和Alox (41-49 mmol kg - 1)，从而产生更大的P吸附能力（PSC: 239-287 vs. 44-155 mmol kg - 1）。两个地点的磷饱和度（DPS）都很低（10%）。在冬季或湿田条件下，Feox池的Fe(III)（氧）氧化物还原程度高达100%，表明Feox池完全溶解。尽管大量减少，但Løvenborg的可溶性磷（PSol）仍然很低（≤0.3 mg L−1），而Vejrumbro的PSol浓度很高（高达4.7 mg L−1）。粉末x射线衍射和Mössbauer光谱证实在Løvenborg形成了vivianite，证明P通过沉淀固定。此外，利用地球化学模型Minteq计算的Løvenborg土壤的钙磷沉淀饱和度指数在2.5 ~ 4.2之间，而对于羟基磷灰石等钙磷沉淀，Løvenborg土壤表现为接近平衡（0.09）至轻度欠饱和（- 1.8）。而在Vejrumbro中，P的滞留主要是通过吸附在残余的Fe和Al氧化物矿物上。这些结果表明，P释放风险模型必须超越再吸附，并包括沉淀途径，这取决于金属氧化物含量、阳离子有效性（如Ca2+、Fe2+）、pH、碱度和Fe（III）还原程度。结合关键的地球化学指标，如pH、吸附能力、钙含量、铁（III）还原程度和碱度，可以更好地分类泥炭土，并指导保证最小磷释放的再湿策略。
{"title":"Phosphorus dynamics in acidic and neutral fen soils − does vivianite limit phosphorus release?","authors":"Adrian F. Florea , Dominik H. Zak , Rasmus Jes Petersen , Carolin L. Dreher , Andreas Kappler , Hans Christian B. Hansen","doi":"10.1016/j.geoderma.2026.117685","DOIUrl":"10.1016/j.geoderma.2026.117685","url":null,"abstract":"<div><div>Drainage and cultivation of organic lowland peat soils have profoundly altered their hydrological and biogeochemical functions, increasing greenhouse gas emissions and phosphorus (P) mobilization due to enhanced mineralization. Rewetting is increasingly promoted to mitigate these impacts. However, intensive agricultural use has led to P accumulation, primarily bound to Fe(III)(oxyhydr)oxide minerals, raising the risk of P release under anoxic conditions and challenging the restoration of these systems as nutrient sinks. Predicting P release remains difficult due to complex interactions, including P re-sorption to metal oxides with remaining P binding places and precipitation as Fe(II) or Ca phosphates such as vivianite and hydroxyapatite.</div><div>This study investigates Fe(III)(oxyhydr)oxide reduction extent and associated P mobilization in two contrasting Danish lowland peatlands over 24 months: the acidic Vejrumbro and neutral-alkaline Løvenborg. Oxalate-extractable Fe, Al, and P (Fe<sub>ox</sub>, Al<sub>ox</sub>, P<sub>ox</sub>) differed substantially between sites. Løvenborg exhibited higher Fe<sub>ox</sub> (198–241 mmol kg<sup>−1</sup>) and Al<sub>ox</sub> (41–49 mmol kg<sup>−1</sup>) than Vejrumbro (Fe<sub>ox</sub>: 27–122 mmol kg<sup>−1</sup>; Al<sub>ox</sub>: 4.5–40 mmol kg<sup>−1</sup>), resulting in greater P sorption capacity (PSC: 239–287 vs. 44–155 mmol kg<sup>−1</sup>). The degree of P saturation (DPS) remained low at both sites (<10%).</div><div>Under winter or wet field conditions, Fe(III)(oxyhydr)oxide reduction extent reached up to 100%, indicating complete dissolution of the Fe<sub>ox</sub> pool. Despite extensive reduction, soluble P (P<sub>Sol</sub>) remained low in Løvenborg (≤0.3 mg L<sup>−1</sup>), whereas Vejrumbro exhibited high P<sub>Sol</sub> concentrations (up to 4.7 mg L<sup>−1</sup>). Powder X-ray diffraction and Mössbauer spectroscopy confirmed vivianite formation in Løvenborg, demonstrating P immobilization via precipitation. Moreover, in Løvenborg, the saturation index calculated using the geochemical model Minteq showed values between 2.5 and 4.2 with respect to vivianite supersaturation, while for Ca-P precipitates such as hydroxyapatite, Løvenborg soils show near equilibrium (0.09) to slight undersaturation (−1.8). In contrast, P retention in Vejrumbro was mainly through adsorption onto residual Fe and Al oxide minerals.</div><div>These results indicate that P release risk models must go beyond re-adsorption, and include precipitation pathways, which depend on metal-oxide content, cation availability (e.g., Ca<sup>2+</sup>, Fe<sup>2+</sup>), pH, alkalinity, and the extent of Fe(III) reduction. Incorporating key geochemical indicators—such as pH, sorption capacity, calcium content, Fe(III) reduction extent, and alkalinity may lead to better classification of peat soils and guide rewetting strategies safeguarding minimal P release.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"466 ","pages":"Article 117685"},"PeriodicalIF":6.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146000552","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}
Pub Date : 2026-02-01Epub Date: 2026-01-21DOI: 10.1016/j.geoderma.2026.117678
Lucas Raimundo Bento , Ladislau Martin-Neto , João Vitor dos Santos , Vitor Silveira Freitas , José Ricardo Macedo Pezzopane , Alberto Carlos de Campos Bernardi , Patrícia Perondi Anchão Oliveira , Steffen A. Schweizer
Pasture management is pivotal for enhancing soil organic carbon (SOC) storage in tropical grasslands, yet SOC recovery is often considered merely as the replenishment of historical losses following land-use change. It remains unclear whether managed Ferralsols can surpass the SOC stocks of native vegetation (NV) and which mechanisms drive such gains. We evaluated SOC pools, chemical composition, and nutrient-holding capacity after 24 years under unmanaged degraded pasture (DP) and fertilized managed pasture (MP), relative to NV. SOC storage in these systems was primarily mediated by the mineral-associated organic matter (MAOM) pool. Compared to NV, DP soils exhibited reduced MAOM stocks (119 vs. 92 Mg C ha−1), whereas MP soils stored 148 Mg C ha−1. In DP, soil acidity, low nutrient availability, and poor forage inputs induced microbial stress (as revealed by phospholipid fatty acid profiles), likely constraining MAOM formation and yielding MAOM enriched in carbohydrates with fewer carbonyl groups. In contrast, liming and fertilization in MP alleviated the Ferralsol’s low pH and nutrient deficiencies, enhancing forage yields and reducing microbial stress, likely promoting MAOM with more microbially processed signatures. NanoSIMS analyses revealed microscale organic matter patches sparsely covering clay-sized particles, indicating that SOC storage is decoupled from mineral surface area and highlighting the role of organic inputs and microbial activity in MAOM formation. Higher MAOM under MP not only increased SOC stocks but also enhanced cation exchange capacity, demonstrating that targeted pasture management can exceed native SOC stocks while improving nutrient retention.
草地管理是提高热带草原土壤有机碳（SOC）储量的关键，但SOC恢复通常被认为仅仅是土地利用变化后历史损失的补充。目前尚不清楚管理的feralsols是否能够超过原生植被（NV）的SOC储量，以及驱动这种收益的机制是什么。本研究对比了无管理退化草场（DP）和施肥管理草场（MP） 24年后土壤有机碳库、化学组成和养分保持能力。结果表明，土壤有机碳储量主要由矿物相关有机质（MAOM）库介导。与NV相比，DP土壤的MAOM储量减少（119比92 Mg C ha - 1），而MP土壤的MAOM储量为148 Mg C ha - 1。在DP中，土壤酸度、低养分有效性和较差的饲料投入诱导了微生物胁迫（如磷脂脂肪酸谱所示），可能限制了MAOM的形成，并产生富含较少羰基碳水化合物的MAOM。相比之下，MP的石灰化和施肥缓解了Ferralsol的低pH和养分缺乏，提高了牧草产量，减少了微生物胁迫，可能促进了具有更多微生物处理特征的MAOM。NanoSIMS分析显示，微尺度的有机质斑块稀疏地覆盖在粘土大小的颗粒上，表明有机碳储量与矿物表面积分离，并突出了有机输入和微生物活动在MAOM形成中的作用。高MAOM不仅增加了土壤有机碳储量，还增强了阳离子交换能力，表明有针对性的牧场管理可以在提高土壤有机碳储量的同时提高养分保有量。
{"title":"Pasture management in Ferralsols drives mineral-associated organic matter storage, exceeding native soil carbon stocks and enhancing cation exchange capacity","authors":"Lucas Raimundo Bento , Ladislau Martin-Neto , João Vitor dos Santos , Vitor Silveira Freitas , José Ricardo Macedo Pezzopane , Alberto Carlos de Campos Bernardi , Patrícia Perondi Anchão Oliveira , Steffen A. Schweizer","doi":"10.1016/j.geoderma.2026.117678","DOIUrl":"10.1016/j.geoderma.2026.117678","url":null,"abstract":"<div><div>Pasture management is pivotal for enhancing soil organic carbon (SOC) storage in tropical grasslands, yet SOC recovery is often considered merely as the replenishment of historical losses following land-use change. It remains unclear whether managed Ferralsols can surpass the SOC stocks of native vegetation (NV) and which mechanisms drive such gains. We evaluated SOC pools, chemical composition, and nutrient-holding capacity after 24 years under unmanaged degraded pasture (DP) and fertilized managed pasture (MP), relative to NV. SOC storage in these systems was primarily mediated by the mineral-associated organic matter (MAOM) pool. Compared to NV, DP soils exhibited reduced MAOM stocks (119 vs. 92 Mg<!--> <!-->C<!--> <!-->ha<sup>−1</sup>), whereas MP soils stored 148 <!--> <!-->Mg<!--> <!-->C<!--> <!-->ha<sup>−1</sup>. In DP, soil acidity, low nutrient availability, and poor forage inputs induced microbial stress (as revealed by phospholipid fatty acid profiles), likely constraining MAOM formation and yielding MAOM enriched in carbohydrates with fewer carbonyl groups. In contrast, liming and fertilization in MP alleviated the Ferralsol’s low pH and nutrient deficiencies, enhancing forage yields and reducing microbial stress, likely promoting MAOM with more microbially processed signatures. NanoSIMS analyses revealed microscale organic matter patches sparsely covering clay-sized particles, indicating that SOC storage is decoupled from mineral surface area and highlighting the role of organic inputs and microbial activity in MAOM formation. Higher MAOM under MP not only increased SOC stocks but also enhanced cation exchange capacity, demonstrating that targeted pasture management can exceed native SOC stocks while improving nutrient retention.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"466 ","pages":"Article 117678"},"PeriodicalIF":6.6,"publicationDate":"2026-02-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"146014527","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}
Pub Date : 2026-01-01Epub Date: 2025-12-10DOI: 10.1016/j.geoderma.2025.117645
Hamza Jouichat, Lotfi Khiari
Soil acidity management often relies on lime recommendation methods that are imprecise, time-consuming, or involve hazardous reagents like the SMP buffer solution. This study introduces an alternative approach by developing and evaluating machine learning (ML) models to predict the change in soil pH (ΔpH) following incremental applications of hydrated lime (Ca(OH)2). A total of 418 soil samples from Eastern North America were analyzed for their chemical properties, mid-infrared (MIR) spectral signatures, and complete titration curves obtained through acid-base neutralization. Three ML models were tested: a Chemical Signature Model (CSM) based on routine soil analyses, a Spectral Signature Model (SSM) relying solely on MIR spectra, and a Hybrid Model (HM) combining both data sources. All models demonstrated high accuracy, achieving R2 values above 92 % and RMSE values below 0.21 pH units. The HM achieved the highest performance (R2 = 94 %, RMSE = 0.18), closely followed by the SSM, indicating the practical equivalence of the two approaches since converting ΔpH curves into absolute pH curves always requires the initial soil pH. SHapley Additive exPlanations (SHAP) values were used to interpret variable importance in each model. In the CSM, lime dose and initial pH were dominant predictors, followed by organic matter, Mehlich-3 extractable Ca (CaM3), and Al (AlM3). In the SSM and HM models, specific MIR spectral regions corresponding to hydroxyl, carboxylic, silicate, and organo-mineral functional groups were highly informative, confirming consistency with known soil chemistry principles.
These findings enable the automated reconstruction of titration curves, paving the way for dynamic, accurate, and safe lime recommendation systems tailored to laboratory capabilities: CSM for immediate implementation and SSM or HM for laboratories adopting MIR spectroscopy. This approach aligns with precision agriculture principles, supporting sustainable and site-specific management of soil acidity.
{"title":"Reconstructing soil acidity neutralization curves using Machine learning and chemical or spectral soil signatures","authors":"Hamza Jouichat, Lotfi Khiari","doi":"10.1016/j.geoderma.2025.117645","DOIUrl":"10.1016/j.geoderma.2025.117645","url":null,"abstract":"<div><div>Soil acidity management often relies on lime recommendation methods that are imprecise, time-consuming, or involve hazardous reagents like the SMP buffer solution. This study introduces an alternative approach by developing and evaluating machine learning (ML) models to predict the change in soil pH (ΔpH) following incremental applications of hydrated lime (Ca(OH)<sub>2</sub>). A total of 418 soil samples from Eastern North America were analyzed for their chemical properties, mid-infrared (MIR) spectral signatures, and complete titration curves obtained through acid-base neutralization. Three ML models were tested: a Chemical Signature Model (CSM) based on routine soil analyses, a Spectral Signature Model (SSM) relying solely on MIR spectra, and a Hybrid Model (HM) combining both data sources. All models demonstrated high accuracy, achieving R<sup>2</sup> values above 92 % and RMSE values below 0.21 pH units. The HM achieved the highest performance (R<sup>2</sup> = 94 %, RMSE = 0.18), closely followed by the SSM, indicating the practical equivalence of the two approaches since converting ΔpH curves into absolute pH curves always requires the initial soil pH. SHapley Additive exPlanations <strong>(</strong>SHAP) values were used to interpret variable importance in each model. In the CSM, lime dose and initial pH were dominant predictors, followed by organic matter, Mehlich-3 extractable Ca (Ca<sub>M3</sub>), and Al (Al<sub>M3</sub>). In the SSM and HM models, specific MIR spectral regions corresponding to hydroxyl, carboxylic, silicate, and organo-mineral functional groups were highly informative, confirming consistency with known soil chemistry principles.</div><div>These findings enable the automated reconstruction of titration curves, paving the way for dynamic, accurate, and safe lime recommendation systems tailored to laboratory capabilities: CSM for immediate implementation and SSM or HM for laboratories adopting MIR spectroscopy. This approach aligns with precision agriculture principles, supporting sustainable and site-specific management of soil acidity.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"465 ","pages":"Article 117645"},"PeriodicalIF":6.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145730837","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}
Root carbon (C) inputs play a pivotal role in mediating the formation, accumulation, and turnover of soil organic C (SOC). However, how different root functional modules (absorptive roots [ARs] vs. transport roots [TRs]) regulate SOC dynamics under elevated atmospheric nitrogen (N) deposition remains unclear. By separately collecting rhizosphere soils of ARs and TRs and quantifying SOC accumulation therein, we characterized the distinct roles of these two root modules in regulating SOC dynamics in a subtropical karst forest subjected to different rates of N additions. Nitrogen addition promoted SOC accumulation in the rhizosphere of both ARs and TRs, especially at higher N-addition rate. Moreover, the rhizosphere SOC contents of ARs were significantly higher than those of TRs across N-addition treatments. Correlation analysis indicated that under the influence of ARs, SOC content was significantly and positively correlated with both protective mineral-associated SOC poos and microbial carbon pump (MCP) efficacy. By contrast, in the context of TRs, a significantly positive association was observed exclusively between SOC content and protective mineral pools, with no significant correlation of SOC content with MCP efficacy. These findings suggest that ARs outweigh TRs in mediating the effects of N addition on SOC accumulation. Mechanisms driving N-induced SOC accumulation may differ between two root functional modules, with each module governing distinct regulatory pathways. This study highlights the necessity to integrate root functional traits, particularly those distinguishing ARs and TRs, into process-based predictive frameworks of ecosystem C cycling. Such integration is critical for improving the mechanistic understanding and predictive accuracy of soil C dynamics in the context of projected N deposition regimes.
{"title":"Absorptive roots outweigh transport roots in modulating nitrogen-addition effects on soil organic carbon accumulation in a subtropical forest","authors":"Yuanshuang Yuan , Xianwang Du , Yicong Yin , Bartosz Adamczyk , Ziliang Zhang","doi":"10.1016/j.geoderma.2025.117571","DOIUrl":"10.1016/j.geoderma.2025.117571","url":null,"abstract":"<div><div>Root carbon (C) inputs play a pivotal role in mediating the formation, accumulation, and turnover of soil organic C (SOC). However, how different root functional modules (absorptive roots [ARs] vs. transport roots [TRs]) regulate SOC dynamics under elevated atmospheric nitrogen (N) deposition remains unclear. By separately collecting rhizosphere soils of ARs and TRs and quantifying SOC accumulation therein, we characterized the distinct roles of these two root modules in regulating SOC dynamics in a subtropical karst forest subjected to different rates of N additions. Nitrogen addition promoted SOC accumulation in the rhizosphere of both ARs and TRs, especially at higher N-addition rate. Moreover, the rhizosphere SOC contents of ARs were significantly higher than those of TRs across N-addition treatments. Correlation analysis indicated that under the influence of ARs, SOC content was significantly and positively correlated with both protective mineral-associated SOC poos and microbial carbon pump (MCP) efficacy. By contrast, in the context of TRs, a significantly positive association was observed exclusively between SOC content and protective mineral pools, with no significant correlation of SOC content with MCP efficacy. These findings suggest that ARs outweigh TRs in mediating the effects of N addition on SOC accumulation. Mechanisms driving N-induced SOC accumulation may differ between two root functional modules, with each module governing distinct regulatory pathways. This study highlights the necessity to integrate root functional traits, particularly those distinguishing ARs and TRs, into process-based predictive frameworks of ecosystem C cycling. Such integration is critical for improving the mechanistic understanding and predictive accuracy of soil C dynamics in the context of projected N deposition regimes.</div></div>","PeriodicalId":12511,"journal":{"name":"Geoderma","volume":"465 ","pages":"Article 117571"},"PeriodicalIF":6.6,"publicationDate":"2026-01-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"145823031","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}
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