Soil最新文献

{"title":"Mineral-bound organic carbon exposed by hillslope thermokarst terrain: case study in Cape Bounty, Canadian High Arctic","authors":"Maxime Thomas, Julien Fouché, Hugues Titeux, Charlotte Morelle, Nathan Bemelmans, Melissa J. Lafrenière, Joanne K. Heslop, Sophie Opfergelt","doi":"10.5194/egusphere-2025-3428","DOIUrl":"https://doi.org/10.5194/egusphere-2025-3428","url":null,"abstract":"<strong>Abstract.</strong> Arctic landscapes could add 55–230 Pg of carbon (in CO₂ equivalent) to the atmosphere, through CO₂ and CH₄ emissions, by the end of this century. These estimates could be quantified more accurately by constraining the contribution of rapid thawing processes such as thermokarst landscapes to permafrost carbon loss, and by investigating the exposed organic carbon (OC) interacting with mineral surfaces or metallic cations, i.e., the nature of these interactions and what controls their relative abundance. Here, we investigate two contrasted types of hillslope thermokarst landscapes: an Active Layer Detachment (ALD) which is a one-time event, and a Retrogressive Thaw Slump (RTS) which repeats annually during summer months in the Cape Bounty Arctic Watershed Observatory (Melville Island, Canada). We analyzed mineralogy, total and soluble element concentrations, total OC and mineral-OC interactions within the headwalls of both disturbances, and within corresponding undisturbed profiles. Our results show that OC stabilized by chemical bonds account for 13 ± 5 % of total OC in the form of organo-metallic complexes and up to 6 ± 2 % associated with poorly crystalline iron oxides. If we add the mechanisms of physical protection of particulate organic matter in aggregates and larger molecules stabilized by chemical bonds, we reach 64 ± 10 % of the total OC being stabilized. Importantly, we observe a decrease in the proportion of mineral-bound OC in the deeper layers exposed by the retrogressive thaw slump: the proportion of organo-metallic complexes drops from ~18 % in surface samples to ~1 % in the deepest samples. These results therefore suggest that the OC exposed by thermokarst disturbances at Cape Bounty is protected by interactions with minerals to a certain extent, but that deep thaw features could expose OC more readily accessible to degradation.","PeriodicalId":48610,"journal":{"name":"Soil","volume":"51 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144677491","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":"Using Monte Carlo conformal prediction to evaluate the uncertainty of deep-learning soil spectral models","authors":"Yin-Chung Huang, José Padarian, Budiman Minasny, Alex B. McBratney","doi":"10.5194/soil-11-553-2025","DOIUrl":"https://doi.org/10.5194/soil-11-553-2025","url":null,"abstract":"Abstract. Uncertainty quantification is a crucial step in the practical application of soil spectral models, particularly in supporting real-world decision making and risk assessment. While machine learning has made remarkable strides in predicting various physiochemical properties of soils using spectroscopy, its practical utility in decision making remains limited without quantified uncertainty. Despite its importance, uncertainty quantification is rarely incorporated into soil spectral models, with existing methods facing significant limitations. Existing methods are either computationally demanding, fail to achieve the desired coverage of observed data, or struggle to handle out-of-domain uncertainty. This study introduces an innovative application of Monte Carlo conformal prediction (MC-CP) to quantify uncertainty in deep-learning models for predicting clay content from mid-infrared spectroscopy. We compared MC-CP with two established methods: (1) Monte Carlo dropout and (2) conformal prediction. Monte Carlo dropout generates prediction intervals for each sample and can address larger uncertainties associated with out-of-domain data. Conformal prediction, on the other hand, guarantees ideal coverage of true values but generates unnecessarily wide prediction intervals, making it overly conservative for many practical applications. Using 39 177 samples from the mid-infrared spectral library of the Kellogg Soil Survey Laboratory to build convolutional neural networks, we found that Monte Carlo dropout itself falls short in achieving the desired coverage – its 90 % prediction intervals only covered the observed values in 74 % of the cases, well below the expected 90 % coverage. In contrast, MC-CP successfully combines the strengths of both methods. It achieved a prediction interval coverage probability of 91 %, closely matching the expected 90 % coverage and far surpassing the performance of the Monte Carlo dropout. Additionally, the mean prediction interval width for MC-CP was 9.05 %, narrower than the conformal prediction's 11.11 %. The success of MC-CP enhances the real-world applicability of soil spectral models, paving the way for their integration into large-scale machine learning models, such as soil inference systems, and further transforming decision making and risk assessment in soil science.","PeriodicalId":48610,"journal":{"name":"Soil","volume":"282 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-07-22","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144677499","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":"Restorative Mitigation of Contaminated Soil for Ecosystem Services: Influences from Research Enterprise and Sustainable Development Goals","authors":"Isak Rajjak Shaikh, Parveen Rajjak Shaikh","doi":"10.5194/egusphere-2025-271","DOIUrl":"https://doi.org/10.5194/egusphere-2025-271","url":null,"abstract":"<strong>Abstract.</strong> Soil is a vital component of the ecosystem, as it provides nutrients needed for the growth of plants and supports all terrestrial life on the planet. The global agricultural sector underwent enormous change after the World Wars, thanks to some important developments in technology transfer that saw increased crop production during the Green Revolution of the 1960s; the initiatives included the use of high yielding variety seeds and also the application of synthetic agrochemicals as nutrient inputs and crop protection agents. This was meant secure food grains for growing human population. Despite all the achievements, the initiatives taken during the Green Revolution are meeting with some harsh criticism now. Soil is under constant pressure due to irresponsible land use and resource exploitation, erosion, escalating climate change, and also the indiscriminate usage of synthetic pesticides and fertilizers. Synthetic pesticides are contaminating soil, and the contaminants are making serious alterations to the content and most importantly to the chemical quality, properties and functions of soil, requiring an immediate risk assessment owing to the hazard and scientific uncertainty surrounding it. Soil pollution is one of the most serious concerns of our time, which not only limits the sustainability of community livelihood but also compromises ecosystem services, causing depletion in its fertility and risks to the environmental and human health. So, the environmentalists, economists, and social scientists have begun advocating more organic amendments to farming and restoration of ecosystems services of soil. Researchers explore physico-chemical and biological methods to mitigate the soil contamination. Research enterprise, local policy making, and globalized discourses on environment at the highest decision-making authority of intergovernmental organizations are being directed towards sustainable future of socio-ecological system.","PeriodicalId":48610,"journal":{"name":"Soil","volume":"36 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144645633","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":"Interplay of coprecipitation and adsorption processes: deciphering amorphous mineral–organic associations under both forest and cropland conditions","authors":"Floriane Jamoteau, Emmanuel Doelsch, Nithavong Cam, Clément Levard, Thierry Woignier, Adrien Boulineau, Francois Saint-Antonin, Sufal Swaraj, Ghislain Gassier, Adrien Duvivier, Daniel Borschneck, Marie-Laure Pons, Perrine Chaurand, Vladimir Vidal, Nicolas Brouilly, Isabelle Basile-Doelsch","doi":"10.5194/soil-11-535-2025","DOIUrl":"https://doi.org/10.5194/soil-11-535-2025","url":null,"abstract":"Abstract. Mineral–organic associations are crucial carbon and nutrient reservoirs in soils. However, conversion from forest to agricultural systems disrupts these associations, leading to carbon loss and reduced soil fertility in croplands. Identifying the types of mineral–organic associations within a single soil is already challenging, and detecting those susceptible to disruption during forest-to-crop conversion is even more complex. Yet, addressing this identification challenge is essential for devising strategies to preserve organic matter in croplands. Here, we aimed to identify the predominant mineral–organic associations within an Andosol (developed on Fe-poor parent material) under both forest and cropland conditions. To achieve this, we collected Andosol samples from both a forested and a cultivated area, located 300 m apart. We then analyzed differences between the two soil profiles in soil physicochemical parameters and characterized mineral–organic associations using an array of spectro-microscopic techniques for comprehensive structural and compositional analysis. At microscale and nanoscale spatial resolution, we observed mineral–organic associations in the form of amorphous coprecipitates, composed of a mix of C+Al+Si and C+Al+Fe+Si nanoCLICs (inorganic oligomers with organics), proto-imogolites and organic matter, some Fe nanophases associated with organic matter, and some metal–organic complexes. This challenges prior conceptions of mineral–organic associations in Andosols by demonstrating the presence of amorphous coprecipitates rather than solely organic matter associated with short-range-order minerals (i.e., imogolite and allophanes). Moreover, chemical mappings suggested that these amorphous coprecipitates may adhere to mineral surfaces (i.e., phyllosilicates and imogolites), revealing secondary interactions of mineral–organic associations in soils. While the presence of similar amorphous coprecipitates in both the forest and crop Andosols was confirmed, the crop soil had 75 % less C in mineral–organic associations (in the 0–30 cm depth). Although the sample size for comparing land use types is limited, these results suggest that the nature of mineral–organic associations remains identical despite quantitative differences. This study highlights the crucial role of amorphous coprecipitates in C stabilization in Andosols and also suggests their vulnerability to disruption after 30 years of a forest-to-crop conversion, thereby challenging our understanding of the persistence of mineral–organic associations in Andosols.","PeriodicalId":48610,"journal":{"name":"Soil","volume":"24 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-07-17","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144645632","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":"Drivers and CO2 flux budgets in a Sahelian Faidherbia albida agro-silvo-pastoral parkland: Insights from continuous high-frequency soil chamber measurements and Eddy Covariance","authors":"Seydina Mohamad Ba, Olivier Roupsard, Lydie Chapuis-Lardy, Frédéric Bouvery, Yélognissè Agbohessou, Maxime Duthoit, Aleksander Wieckowski, Torbern Tagesson, Mohamed Habibou Assouma, Espoir Koudjo Gaglo, Claire Delon, Bienvenu Sambou, Dominique Serça","doi":"10.5194/egusphere-2025-2660","DOIUrl":"https://doi.org/10.5194/egusphere-2025-2660","url":null,"abstract":"<strong>Abstract.</strong> Agroforestry systems — combining trees with crops and/or livestock — are increasingly promoted as sustainable and climate-resilient land-use strategies. Despite their widespread presence in the Sahel, experimental data on their potential as carbon sinks are scarce. This study presents a full-year, high-frequency dataset of CO₂ fluxes in a Sahelian agro-silvo-pastoral parkland dominated by <em>F. albida</em>, located in Senegal’s groundnut basin. CO₂ fluxes were continuously measured using automated static chambers, allowing the quantification of soil and crop respiration (Rch), gross primary production (GPPch), and net carbon exchange (FCO₂ch) under both full sun and shaded (under tree canopies) environments. Seasonal patterns of CO₂ fluxes were similar in both environments, with peaks during the rainy season. Rch and GPPch were significantly higher under tree canopies, indicating a ‘fertile island’ effect. CO₂ flux variability was primarily driven by soil moisture and leaf area index. Chamber-based GPP estimates closely matched those from Eddy Covariance measurements. On an annual scale, <em>F. albida</em> trees contributed approximately 50 % of total ecosystem GPP, with a carbon use efficiency of 0.48. Net annual CO₂ exchange was estimated at −1.4 ± 0.02 and −1.8 ± 0.01 Mg C-CO₂ ha⁻¹ using chamber and Eddy Covariance methods, respectively. These findings underscore the role of <em>F. albida</em>-based agroforestry systems as effective carbon sinks in Sahelian landscapes, supporting their potential contribution to climate change mitigation.","PeriodicalId":48610,"journal":{"name":"Soil","volume":"14 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-07-16","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144645268","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":"Measurement of greenhouse gas fluxes in agricultural soils with a flexible, open-design automated system","authors":"Samuel Franco-Luesma, María Alonso-Ayuso, Benjamin Wolf, Borja Latorre, Jorge Álvaro-Fuentes","doi":"10.5194/soil-11-523-2025","DOIUrl":"https://doi.org/10.5194/soil-11-523-2025","url":null,"abstract":"Abstract. Over the last decades and due to the current climate change situation, the study of the impacts of human activities on climate has reached great importance, with agriculture being one of the main sources of soil greenhouse gas. There are different techniques to quantify the soil gas fluxes, such as micrometeorological techniques or chamber techniques, with the last one being capable of assessing different treatments at the same site. Manual chambers are the most common technique. However, manual chambers are characterized by low sampling frequency; typically, one sample per day is considered to be a high sampling frequency. Therefore, a great deal of effort is required to monitor short-term emission events such as fertilization or rewetting. For this reason, automated chamber systems present an opportunity to improve soil gas flux determination, but their distribution is still scarce due to the cost and challenging technical implementation. The objective of this study was to develop an automated chamber system for agricultural systems and to compare it with a manual chamber system. Moreover, over a period of 1 month, the soil gas fluxes were determined by both systems to compare their capabilities in capturing the temporal variability of soil gas emissions. The automated system reported soil greenhouse gas (GHG) fluxes that were up to 58 % and 40 % greater for CO2 and N2O fluxes compared to the manual chamber system. Additionally, the higher sampling frequency of the automated chamber system allowed us to capture the daily flux variations, resulting in a more accurate estimation of cumulative soil gas emissions. Furthermore, the assessment of various sampling intervals for single-day measurements indicated that between 10:00 and 12:00 LT was the optimal time interval for soil gas sampling in order to obtain representative daily emissions. This study emphasizes the importance of chamber dimension and shape in the development of chamber systems, as well as the sampling frequency and sampling hour for manual chamber systems.","PeriodicalId":48610,"journal":{"name":"Soil","volume":"7 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-07-14","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144622232","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":"Rubber plant root properties induce contrasting soil aggregate stability through cohesive force and reduced land degradation risk in southern China","authors":"Waqar Ali, Amani Milinga, Tao Luo, Mohammad Nauman Khan, Asad Shah, Khurram Shehzad, Qiu Yang, Huai Yang, Wenxing Long, Wenjie Liu","doi":"10.5194/soil-11-507-2025","DOIUrl":"https://doi.org/10.5194/soil-11-507-2025","url":null,"abstract":"Abstract. In southern China, the island of Hainan faces land degradation risks due to a combination of soil physical, chemical, and climatic factors: soil physical properties like a high proportion of microaggregates (<0.25 mm), chemical properties such as low soil organic matter (SOM) content, and a climatic factor of frequent uneven rainfall. The cohesive force between soil particles, which is influenced by plant root properties and root-derived SOM, is essential for improving soil aggregate stability and mitigating land degradation. However, the mechanisms by which rubber plant root properties and root-derived SOM affect soil aggregate stability through cohesive forces in tropical regions remain unclear. This study evaluated rubber plants of different ages to assess the effects of root properties and root-derived SOM on soil aggregate stability and cohesive forces. Older rubber plants (>11 years old) showed greater root diameters (RDs) (0.81–0.91 mm), higher root length (RL) densities (1.83–2.70 cm cm−3), and increased proportions of fine (0.2–0.5 mm) and medium (0.5–1 mm) roots, leading to higher SOM due to lower lignin and higher cellulose contents. Older plants exhibited higher soil cohesion, with significant correlations among root characteristics, SOM, and cohesive force, whereas the random forest (RF) model identified aggregates (>0.25 mm), root properties, SOM, and cohesive force as the key factors influencing mean weight diameter (MWD) and geometric mean diameter (GMD). Furthermore, partial least squares path models (PLS-PM) showed that the RL density (RLD) directly influenced SOM (path coefficient 0.70) and root-free cohesive force (RFCF) (path coefficient 0.30), which subsequently affected the MWD, with additional direct RLD effects on the SOM (path coefficient 0.45) and MWD (path coefficient 0.64) in the surface soil. Cohesive force in rubber plants of different ages increased macroaggregates (>0.25 mm) and decreased microaggregates (<0.25 mm), with topsoil average MWD following the order control (CK) (0.98 mm) < 5Y_RF (1.26 mm) < mixed forest (MF; 1.31 mm) < 11Y_RF (1.36 mm) < 27Y_RF (1.48 mm) < 20Y_RF (1.51 mm). Rubber plant root traits enhance soil aggregate stability and mitigate land degradation risk in tropical regions, offering practical soil restoration strategies through targeted root trait selection to strengthen soil cohesion, ensure long-term agricultural productivity, and preserve environmental quality, highlighting the need for further research across diverse ecological zones and forest types.","PeriodicalId":48610,"journal":{"name":"Soil","volume":"35 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-07-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144603107","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":"Formation of mineral-associated organic matter via rock weathering: an experimental test for the organo-metallic glue hypothesis","authors":"Kaori Matsuoka, Jo Jinno, Hiroaki Shimada, Emi Matsumura, Ryo Shingubara, Rota Wagai","doi":"10.5194/egusphere-2025-2840","DOIUrl":"https://doi.org/10.5194/egusphere-2025-2840","url":null,"abstract":"&lt;strong&gt;Abstract.&lt;/strong&gt; Mineral-associated organic matter (MAOM), representing the dominant form of relatively stable C in soil, contains high physicochemical heterogeneity. The co-localization of organic matter (OM) with reactive aluminum (Al) and iron (Fe) phases in various MAOM fractions—across a range of natural and cultivated soils from five soil orders—has led to the “organo-metallic glue” hypothesis. The hypothesis proposes that coprecipitates formed between mineral-derived metals and microbially processed OM act as a binding agent, promoting the formation of stable microaggregates and thereby enhancing soil OM persistence. However, the formation mechanism remains unclear as the observed associations reflect multiple soil processes. We thus designed a simple laboratory experiment to test if the supply of metals and metalloids through rock weathering controls MAOM formation and if the OM-to-metal ratio of the material formed is consistent with complexation, sorptive association, or their mixture (i.e., coprecipitates). Two end-member igneous rocks (granite and basalt) crushed to have 38–75 µm size and, additionally, 20–38 µm size for basalt, as well as river sand (100–300 µm) as control were mixed with leaf compost (powdered to 100–250 µm) as single OM source. The mineral-OM mixtures were incubated aerobically at 30 &lt;sup&gt;o&lt;/sup&gt;C with the natural soil microbial community and subjected to 8 wet-and-dry cycles using artificial rainwater (pH 4.73) over a 55-day experiment. The mixtures were then fractionated by density to examine the formation of meso-density, organo-mineral aggregates (1.8–2.4 g cm&lt;sup&gt;–&lt;/sup&gt;&lt;sup&gt;3&lt;/sup&gt;: MF) by distinguishing it from the compost-dominant low-density fraction (&lt; 1.8 g cm&lt;sup&gt;–&lt;/sup&gt;&lt;sup&gt;3&lt;/sup&gt;: LF) and high-density fraction (&gt;2.4 g cm&lt;sup&gt;–&lt;/sup&gt;&lt;sup&gt;3&lt;/sup&gt;: HF) consisting of the crushed rock. The MF formation assessed as C content was 1.49 ± 0.06 mg C g&lt;sup&gt;–1&lt;/sup&gt; rock (fine basalt), 1.04 ± 0.08 (coarse basalt), and 0.62 ± 0.06 (granite) over the 55 days, while the net MF mass increase was detected only in fine basalt due to the presence of meso-density materials in the crushed rock (&lt; 7 % by mass). Faster chemical weathering of the fine basalt was indicated by a significant increase in extractable Fe and Al phases, largely in MF, and the highest leaching of Fe and base cations (esp. Na and Ca). The organo-mineral aggregates formed in the fine basalt treatment had the C-to-metal (Fe+Al) ratio of 0.36 ± 0.01 (molar basis), consistent with organo-metal coprecipitation. Further analysis focusing on the two basalt treatments revealed a significant decline in C:N ratios by 23–25 units and enrichment of δ&lt;sup&gt;13&lt;/sup&gt;C and δ&lt;sup&gt;15&lt;/sup&gt;N by 0.9–1.2 ‰ and 0.6 ‰, respectively, in MFs compared to LFs, indicating a strong contribution of microbial N-containing compounds to the MAOM formation. While microbial community composition differed among the treatments, no significant difference was found in q","PeriodicalId":48610,"journal":{"name":"Soil","volume":"697 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-07-10","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144594127","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":"Evaluating N2O emissions and carbon sequestration in temperate croplands with cover crops: insights from field trials","authors":"Victoria Nasser, René Dechow, Mirjam Helfrich, Ana Meijide, Pauline Sophie Rummel, Heinz-Josef Koch, Reiner Ruser, Lisa Essich, Klaus Dittert","doi":"10.5194/soil-11-489-2025","DOIUrl":"https://doi.org/10.5194/soil-11-489-2025","url":null,"abstract":"Abstract. Cover crops (CCs) are acclaimed for enhancing the environmental sustainability of agricultural practices by aiding in carbon (C) sequestration and reducing losses of soil mineral nitrogen (SMN) after harvest. Yet, their influence on nitrous oxide (N2O) emissions – a potent greenhouse gas – presents a complex challenge, with findings varying across different studies. This research aimed to elucidate the effects of various winter CCs – winter rye (frost-tolerant grass), saia oat (frost-sensitive grass), and spring vetch (frost-sensitive legume) – compared to a bare fallow control on SMN dynamics, N2O emissions, and C sequestration. These effects were determined by measuring SMN dynamics and N2O emissions in field experiments. The effects of CCs on soil C sequestration over a 50-year period were predicted by soil organic C (SOC) models using measured aboveground and belowground CC biomass. While CCs efficiently lowered SMN levels during their growth, they slightly increased N2O emissions compared to bare fallow. In particular, winter frost events triggered significant emissions from the frost-sensitive varieties. Moreover, residue incorporation and tillage practices were associated with increased N2O emissions in all CC treatments. Winter rye, characterized by its high biomass production and nitrogen (N) uptake, was associated with the highest cumulative N2O emissions, highlighting the influence of biomass management and tillage practices on N cycling and N2O emissions. The CC treatment resulted in a slight increase in direct N2O emissions (4.5±3.0, 2.7±1.4, and 3.1±3.8kgN2O-Nha-1 for rye, oat, and vetch, respectively) compared to the fallow (2.6±1.7kgN2O-Nha-1) over the entire trial period (18 months). However, the potential of non-legume CCs to reduce indirect N2O emissions compared to fallow (0.3±0.4 and 0.2±0.1kgN2O-Nha-1a-1 for rye and oat, respectively) and their contribution to C sequestration (120–150 kgCha-1a-1 over a period of 50 years when CCs were grown every fourth year) might partially counterbalance these emissions. Thus, while CCs provide environmental benefits, their net impact on N2O emissions requires further research into optimized CC selection and management strategies tailored to specific site conditions to fully exploit their environmental advantages.","PeriodicalId":48610,"journal":{"name":"Soil","volume":"2 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144577912","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":"Comparative efficacy of individually and combined application of compost, biochar, and bentonite on Ni dynamics in a calcareous soil","authors":"Hamid Reza Boostani, Zahra Jalalpour, Ali Behpouri, Ehsan Bijanzadeh, Mahdi Najafi-Ghiri","doi":"10.5194/egusphere-2025-2147","DOIUrl":"https://doi.org/10.5194/egusphere-2025-2147","url":null,"abstract":"<strong>Abstract.</strong> In Iran, a considerable proportion of agricultural soils are contaminated with various heavy metals (HMs), including nickel (Ni), necessitating remediation to mitigate their transfer into the food chain. However, there remains a scarcity of research on the effectiveness of applying organic and inorganic materials, either individually or in combination, for Ni immobilization in contaminated calcareous soils. To address this gap, an incubation experiment as completely randomized design with three replications was conducted to compare the effect of different soil amendments, either individually or combined (municipal solid waste compost (M), bentonite (B), municipal solid waste compost biochar (MB), M+B, MB+B, MB+M each applied at 2 % wt.) on Ni immobilization in a calcareous soil with three Ni contamination levels (0 (Ni₀), 150 mg kg^-1(Ni₁) and 300 mg kg^-1 (Ni₂). The study employed analytical techniques such as SEM-EDX, XRD, FTIR, sequential extraction, and DTPA-release kinetics to assess the efficiency of these amendments on stabilizing Ni in the soil. Elevating Ni levels from Ni₀ to Ni₂ increased Ni concentrations across all soil fractions, especially in Fe/Mn oxides (FeMnOx) and organic matter (OM). All amendments except M enhanced Ni immobilization by converting more labile fractions (WsEx, Car, FeMnOx) into residual (Res) form. While combined amendments were not more effective than single treatments, MB was the most efficient in stabilizing Ni. MB also exhibited the lowest 'a' and highest 'b' values attributed to the power function kinetics model, indicating superior Ni desorption reduction. These finding are likely due to its alkaline pH, ash content, and phosphorus content, which facilitate Ni precipitation. In contrast, M increased Ni desorption by raising its bioavailability (WsEx and Car fractions). The combined application of biochar (MB) with either bentonite (B) or compost (M) did not exhibit synergistic effects on the immobilization of Ni in the soil. In conclusion, the independent application of municipal solid waste-derived biochar appears to be a potentially effective amendment for enhancing Ni immobilization in contaminated calcareous soils.","PeriodicalId":48610,"journal":{"name":"Soil","volume":"18 1","pages":""},"PeriodicalIF":6.8,"publicationDate":"2025-07-08","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"144577913","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}