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Soil organic matter (SOM) plays a central role for both the C cycle and soil functions. Plants provide the input and heterotrophic (micro)organisms are essential for the turnover. Microbial metabolism links matter and energy fluxes and generates the highest energy turnover dynamics in SOM because the organisms need both energy and matter for maintenance and growth. In this perspectives paper, we evaluate the knowledge on thermodynamic approaches potentially applicable to study the turnover of organic matter in the soil system. Thermodynamics is essential for understanding organic matter turnover in soil as turnover and storage are controlled by the energy supply to, and consumption by, microbes. Instead of just comparing the heat of combustion of compounds without considering microbial anabolism, we need to apply conventional thermodynamic state variables that can be either estimated using established thermodynamic equations, or measured empirically in soil. In particular, we can follow and quantify overall changes of enthalpies by calorimetry. Here, we suggest to apply a thermodynamic concept with the related experimental approaches of calo(respiro)metry and turnover mass balances including biomass formation. This enables us to better interpret and understand the highly variable carbon use efficiency (CUE) in a multi-substrate system such as soil and to relate this to energy use efficiency (EUE). Combining the experimental measurements of the thermodynamic state variables with mass turnover data allow prediction of whether compounds can be metabolized with energy delivery to microorganisms, or be thermodynamically stabilized under the respective redox and electron acceptor conditions. Energy balancing shows how much energy is actually used and retained in the soil, how much is emitted as heat, and how much may be stabilized due to endergonic turnover reactions. Thermodynamic stabilization should therefore be considered as basic stabilization process for organic compounds in soil. • Energy fluxes are essential to sustain active microbes contributing to soil organic matter (SOM). • Dynamic energy and matter fluxes in soil are tightly coupled. • Thermodynamics can describe microbial SOM formation and transformation. • Thermodynamic state variables allow balancing and interpreting of soil processes. • Gibbs energy gain for microbes is dominated by the electron acceptors half-reaction. [ABSTRACT FROM AUTHOR]

Carbon and nitrogen leaching and seepage with subsurface flow is one of the main paths of soil carbon and nitrogen loss. However, as great challenges lie in direct observation, soil carbon and nitrogen leaching related research is relatively lagging behind. Especially due to the complexity of the soil subsurface flow, some problems have not been fully elucidated. In this paper, the characteristics and observation methodologies of soil carbon and nitrogen leaching under the influence of soil, environment and subsurface flow were first summarized, and numerous complicated factors demonstrated to affect carbon and nitrogen leaching, where the influence of rainfall and soil properties were pre-dominant. Field measurement could reflect the natural process of leaching, the indoor experiment could effectively quantify the influential factors on leaching, and the mathematical model could help understand the physical mechanism of carbon and nitrogen leaching by simulating water flow and matter transport in porous media. Future research could combine these methods to achieve a better research effect. The aim of this paper was to provide a certain understanding of the role of carbon and nitrogen in the process of matter cycling and nutrient transfer, and to provide a scientific basis for better regulation of the dynamics of carbon and nitrogen mineralisation, sequestration, leaching and plant uptake in future ecosystems. [ABSTRACT FROM AUTHOR]

Carbon and nitrogen leaching and seepage with subsurface flow is one of the main paths of soil carbon and nitrogen loss. However, as great challenges lie in direct observation, soil carbon and nitrogen leaching related research is relatively lagging behind. Especially due to the complexity of the soil subsurface flow, some problems have not been fully elucidated. In this paper, the characteristics and observation methodologies of soil carbon and nitrogen leaching under the influence of soil, environment and subsurface flow were first summarized, and numerous complicated factors demonstrated to affect carbon and nitrogen leaching, where the influence of rainfall and soil properties were pre-dominant. Field measurement could reflect the natural process of leaching, the indoor experiment could effectively quantify the influential factors on leaching, and the mathematical model could help understand the physical mechanism of carbon and nitrogen leaching by simulating water flow and matter transport in porous media. Future research could combine these methods to achieve a better research effect. The aim of this paper was to provide a certain understanding of the role of carbon and nitrogen in the process of matter cycling and nutrient transfer, and to provide a scientific basis for better regulation of the dynamics of carbon and nitrogen mineralisation, sequestration, leaching and plant uptake in future ecosystems. [ABSTRACT FROM AUTHOR]

The paper presents the results of studies aimed at assessing the variability of respiratory activity of soil microbiota (rates of basal and substrate-induced respiration), as well as of the content of organic matter carbon and microbial biomass carbon in soils formed and functioning in natural (slightly damaged) biogeocenoses along altitudinal gradient from the foothills to the high mountain regions of the Central Caucasus (500–3500 m a.s.l., Elbrus variant of altitudinal zonality, Kabardino-Balkaria). It is shown that the mean values of the studied indicators in surface horizons (0–10 and 0–20 cm, depending on the soil type) significantly increase with the altitude from mountain chernozems to subalpine mountain-meadow soils and significantly decrease at the maximum altitude in the zone of alpine mountain-meadow soils. The studied indicators in different soil types within the same altitudinal zone also differ; this difference is statistically significant (t > 2.5; p < 0.02) for most of the indicators for the compared pairs of soil types. The data obtained indicate that the impact of the altitudinal gradient is significantly transformed by additional factors. The multi-regression analysis has been performed to identify the effect of the main factors of relief (elevation above sea level and slope aspect and steepness) and climate (19 bioclimatic characteristics) on the studied indicators. It shows that the mean cumulative contribution of all 22 factors to the variation of the studied indicators is 40% in mountain chernozems, 66% in mountain-meadow chernozem-like soils, 31% in mountain meadow-steppe subalpine soils, 67% in subalpine mountain-meadow soils, and 67% in alpine mountain-meadow soils. Thus, the effect of the considered factors may significantly differ both for soils located along the altitudinal gradient and for soils functioning within the same altitudinal zone. Relief and climate play an important, but not the only, role in the formation of properties of mountainous soils in the Central Caucasus. [ABSTRACT FROM AUTHOR]

The composition of clay minerals in soils, and more particularly the presence of montmorillonite (as part of the smectite family), is a key factor in soil swell–shrinking as well as off–road vehicle mobility. Detecting these topsoil clay minerals and quantifying the montmorillonite abundance are a challenge since they are usually intimately mixed with other minerals, soil organic carbon and soil moisture content. Imaging spectroscopy coupled with unmixing methods can address these issues, but the quality of the estimation degrades the coarser the spatial resolution is due to pixel heterogeneity. With the advent of UAV-borne and proximal hyperspectral acquisitions, it is now possible to acquire images at a centimeter scale. Thus, the objective of this paper is to evaluate the accuracy and limitations of unmixing methods to retrieve montmorillonite abundance from very-high-resolution hyperspectral images (1.5 cm) acquired from a camera installed on top of a bucket truck over three different agricultural fields, in Loiret department, France. Two automatic endmember detection methods based on the assumption that materials are linearly mixed, namely the Simplex Identification via Split Augmented Lagrangian (SISAL) and the Minimum Volume Constrained Non-negative Matrix Factorization (MVC-NMF), were tested prior to unmixing. Then, two linear unmixing methods, the fully constrained least square method (FCLS) and the multiple endmember spectral mixture analysis (MESMA), and two nonlinear unmixing ones, the generalized bilinear method (GBM) and the multi-linear model (MLM), were performed on the images. In addition, several spectral preprocessings coupled with these unmixing methods were applied in order to improve the performances. Results showed that our selected automatic endmember detection methods were not suitable in this context. However, unmixing methods with endmembers taken from available spectral libraries performed successfully. The nonlinear method, MLM, without prior spectral preprocessing or with the application of the first Savitzky–Golay derivative, gave the best accuracies for montmorillonite abundance estimation using the USGS library (RMSE between 2.2–13.3% and 1.4–19.7%). Furthermore, a significant impact on the abundance estimations at this scale was in majority due to (i) the high variability of the soil composition, (ii) the soil roughness inducing large variations of the illumination conditions and multiple surface scatterings and (iii) multiple volume scatterings coming from the intimate mixture. Finally, these results offer a new opportunity for mapping expansive soils from imaging spectroscopy at very high spatial resolution. [ABSTRACT FROM AUTHOR]

The minimum disturbance of soil is gaining popularity in different parts of the world because of definite advantages over conventional tillage (CT) especially with respect to rice cultivation. Conventionally, rice is transplanted in puddled soil in which soil is completely broken down and destroyed in presence of standing water to create an impervious layer below the surface so as to hold the rainwater for the rice. Such practice noticeably hampers the growth of the succeeding winter crop grown under conventionally tilled soil because of alteration of soil physical characteristics. Taking into consideration, a field experiment was conducted from 2016 to 2019 to assess the alterations in soil properties resulting from various tillage systems in the cultivation of rice followed by Indian mustard, either through transplanting or direct seeding, after the cultivation of Sesbania aculeata. The experiment was conducted with 20 treatment combinations comprising of five tillage practices combining minimum tillage (MT) and conventional tillage (CT) viz., T1: CT (S: Sesbania)-CT (TR: Transplanted rice)-CT (IM: Indian mustard), T2: MT (S)-CT (TR)-MT (IM), T3: MT (S)-CT (DSR: Direct seeded rice)-CT (IM), T4: MT (S)-MT (DSR)-MT + rice residue @1.5 tha−1 (IM), T5: MT (S)-MT (DSR)-MT (IM) and four weed management practices viz., W1: recommended herbicides (S and IM: pendimethalin 0.75 kg ha−1 pre-emergence; rice: pretilachlor 0.75 kg ha−1 pre-emergence) W2: IWM: integrated weed management (W1 + manual weeding), W3: manual weeding/hoeing, W4: weedy check, laid out in a split-plot design with tillage practices in the main plots and weed management practices in the sub-plots with three replications. Weed management is excluded from the results and discussion section of the paper due to no treatment effect on soil properties. The soil properties studied under the investigation were microbial population, microbial biomass carbon, soil enzymes such as dehydrogenase, phosphomonoesterase and fluorescein di-acetate, soil available NPK, soil organic carbon, bulk density, water holding capacity, total porosity, water stable aggregates, and mean weight diameter of aggregates were significantly changed under direct seeded rice based system as compared to puddled rice based system. Findings of the experiment suggested that by minimizing soil disturbance and residue retention in winter crop not only improved soil properties but also system productivity in terms of average rice equivalent yield (18.60%) of rice-Indian mustard cropping sequence over conventional tillage system. Minimum tillage in Sesbania-direct seeded rice-Indian mustard with rice residue retention improved macro water stable aggregates (> 0.25 mm sized aggregates) (62.08%) and mean weight diameter of aggregates (1.34 mm) at 0–30 cm soil depth as compared to conventional tillage system (60.04% and 1.27 mm, respectively). The same treatment improved total porosity and water holding capacity of 0–15 cm of soil depth by 47.42% and 45.87%, respectively as compared to conventional tillage after three years of investigation. Regression analysis shows that one unit reduction in bulk density increased total porosity of soil by 1.47 units; whereas a unit improvement in total porosity improved water holding capacity of soil by 1.25 units. Other soil properties viz., soil organic carbon (16.75% in 0–15 cm depth and 25.86% in 15–30 cm depth), available nitrogen, phosphorous and potassium (1.04%, 5.40% and 1.54%, respectively); bacterial and fungal population, microbial biomass carbon (49.90%), and activity of dehydrogenase, phosphomonoesterase and fluorescein di-acetate (25.39%, 17.02% and 48.94%, respectively) were also improved under the same treatment over conventional tillage system. A significant (P ≤ 0.01) positive correlation of soil macro-aggregates, water holding capacity, soil microbial biomass carbon with soil organic carbon as well as phosphomonoesterase, dehydrogenase and fluorescein di-acetate activities with soil microbial carbon was observed. [ABSTRACT FROM AUTHOR]

【Objective】The paper aimed to explore the impact of different years of abandonment in tropical regions on soil carbon fixing bacterial communities in farmland, and provide theoretical basis and data support for sustainable agricultural management. 【Method】Real time quantitative PCR and high-throughput sequencing technology were used to analyze the gene abundance, community diversity, and differences of soil carbon fixing bacteria in farmland, short-term abandoned land (2＜abandoned years＜5), and long-term abandoned land (abandoned years＞5) in the central region of Hainan Island. 【Result】The abundance of cbbL gene in the soil within the region ranged from 3.11×107-2.84×108 copies/g of dry soil, showing a trend of farmland＞short-term abandoned land＞long-term abandoned land. Compared with the control farmland, long-term abandoned land reduced the Chao1 index, Observed Specifications index and Shannon index of soil carbon fixing bacteria. The dominant phyla of carbon fixing bacteria in tropical farmland soils with different abandonment years were Pseudomonadota and Actinomycetota, and the dominant genera were Bradyrhizobium, Mycobacterium, Rhodopseudomonas, Rubrivivax, Blastochlolis, Nocardia, Mesorhizobium, Dokdonella and Azospirillum, and most of them were facultative autotrophic bacteria. The overall changes in the community structure of soil carbon fixing bacteria with different abandonment years showed clustering according to each abandonment year. A total of 33 differential markers were analyzed for three different abandonment years of soil, including 17 in farmland, 5 in short-term abandonment land, and 11 in long-term abandonment land. The RDA results showed that the community structure of soil carbon fixing bacteria was significantly influenced by SOC, SWC, ROC, TP, TN, Coarse sand, pH and Fine sand. 【Conclusion】The increase in abandoned years has reduced the gene abundance of soil carbon fixing bacteria, and the community structure has also changed. Environmental factors such as SOC, SWC, ROC, TP and TN have a significant impact on the community structure of soil carbon fixing bacteria. [ABSTRACT FROM AUTHOR]

Alder-based shifting cultivation, particularly, has been identified for its unique ecological and socio-economic role. It is a distinctive agricultural practice in Nagaland, India, with significant implications for climate change. This study explores the interactions between alder-based shifting cultivation and climate change dynamics. The paper examines how integrating alders into the shifting cultivation system influences carbon sequestration and soil enrichment in this bio-diversity-rich but environmentally vulnerable region. The paper comprehensively analyses the carbon balance within this managed ecosystem. The findings emphasise alder trees' role in enhancing nitrogen levels in the soil and promoting carbon storage in the biomass and soil organic matter. This paper advocates that agroforestry systems can be effective strategies for climate-resilient development in Nagaland if adequately managed. The study concludes that recognising and reinforcing the role of indigenous practices is crucial in shaping effective and inclusive climate change responses in the region. The other hilly parts of the country can set this as a model. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to study the effects of exogenous straw carbon addition on the organic carbon composition and rice growth characteristics of calcareous paddy soil in karst area, providing reference basis for exploring the changes in carbon composition of alcareous paddy soil in karst areas. 【Method】The rice pot experiment was carried out in the greenhouse of Yanshan Campus of Guilin University of Technology in March 2023, and the experiment period was 120 d. A total of 19 treatments were set up in the pot experiment. In the treatment that only added straw carbon, 0.5%, 1.0% and 3.0% （dry soil mass ratio） crushed straw, straw compost and straw biochar were added, respectively. In the treatment of adding straw carbon and calcium carbonate, the carbon content of the three kinds of straw was 1.0%, and on this basis, 0, 10.0% and 20.0% （dry soil mass ratio） calcium carbonate were added, respectively. At the same time, the control （CK） treatment without adding any substances was set up. The growth characteristics of rice and the changes of soil organic carbon components microbial biomass carbon （MBC), dissolved organic carbon （DOC), granular organic carbon （POC） and their influencing factors were analyzed.【Result】The type and amount of straw carbon had an impact on the content of organic carbon components in the soil. Adding 0.5% straw compost resulted in the highest MBC content in soil （235.73 mg/kg), while adding 1.0% straw compost resulted in the highest DOC content in soil （221.50 mg/kg). The soil treated with 3.0% straw biochar had the highest POC content （36.20 mg/kg). The content of calcium carbonate in soil also affected the composition of soil organic carbon. When the content of calcium carbonate was 20.0%, the soil MBC contents in the treatments adding three straw carbons were the highest. The soil with 10.0% calcium carbonate+1.0% straw compost had the highest DOC content （195.60 mg/kg). The effects of adding three kinds of straw carbon on the growth of rice were as follows: straw biochar ＞ straw compost ＞ broken straw. Among them, the rice with 0.5% straw biochar added had the best growth, with an average plant height of 102 cm and root length of 50 cm. Addition 3.0% crushed straw had the strongest inhibitory effect on rice growth. With the increase of calcium carbonate addition, the rice plant height treated by straw compost increased first and then decreased, and the addition of 10.0% calcium carbonate had a stronger effect on plant height. The correlation analysis results showed that the amount of straw biochar was significantly negatively correlated with soil DOC content （P ＜ 0.05, the same below), and extremely significantly positively correlated with soil POC content （P ＜ 0.01). There was a significant positive correlation between calcium carbonate addition and soil DOC content.【Conclusion】Exogenous straw carbon has a positive excitation effect on the active organic carbon components in calcareous paddy soil, which can greatly increase the contents of MBC, DOC and POC in soil, and the addition of straw carbon and calcium carbonate has a synergistic effect on the increase of soil active carbon components. Adding low amount of straw carbon can promote rice growth, and straw biochar has the most obvious promoting effect. Adding straw compost and straw biochar to soils with 10.0% and 20.0% calcium carbonate concentrations can promote rice growth [ABSTRACT FROM AUTHOR]

Simple Summary: In this paper, the differences in carbon sequestration microbial communities in different wetland types and their main influencing factors were investigated. It was found that the alpha diversity of cbbM carbon-sequestering microorganisms was consistent with the change trend in the total carbon content. Acidithiobacillus was used as a biomarker in lakeside wetlands, and Thiothrix and Thiodictyon were used as biomarkers in marsh wetlands. The diversity of cbbM carbon-fixing microorganisms was primarily influenced by the total nitrogen content, while the community structure was significantly affected by the soil total carbon content. The increase in soil temperature and humidity was conducive to the carbon-sequestering process of Thiomicrospira, Thiomonas, Polaromonas and Acidithiobacillus. The changes in wetland types seriously affected the characteristics of cbbM carbon sequestration in microbial communities, and a warm and humid climate may be conducive to wetland carbon sequestration. Carbon-sequestering microorganisms play an important role in the carbon cycle of wetland ecosystems. However, the response mechanism of carbon-sequestering microbial communities to wetland type changes and their relationship with soil carbon remain unclear. To explore these differences and identify the main influencing factors, this study selected marsh wetlands, river wetlands and lakeside wetlands around Qinghai Lake as research subjects. High-throughput sequencing was employed to analyze the functional gene cbbM of carbon-sequestering microorganisms. The results revealed that the alpha diversity of cbbM carbon-sequestering microorganisms mirrored the trend in total carbon content, with the highest diversity observed in marsh wetlands and the lowest in lakeside wetlands. The dominant bacterial phylum was Proteobacteria, with prevalent genera including Thiothrix, Acidithiobacillus, and Thiodictyon. Acidithiobacillus served as a biomarker in lakeside wetlands, while two other genera were indicative of marsh wetlands. The hierarchical partitioning analysis indicated that the diversity of cbbM carbon-fixing microorganisms was primarily influenced by the total nitrogen content, while the community structure was significantly affected by the soil total carbon content. Moreover, an increased soil temperature and humidity were found to favor the carbon fixation processes of Thiomicrospira, Thiomonas, Polaromonas, and Acidithiobacillus. In summary, changes in wetland types seriously affected the characteristics of cbbM carbon sequestration in microbial communities, and a warm and humid climate may be conducive to wetland carbon sequestration. [ABSTRACT FROM AUTHOR]

Organic carbon performs essential functions in soils, which act as sources or sinks of atmospheric organic carbon. Agricultural management affects the carbon cycle in the soil, with effects on climate change. One of the crops most vulnerable to climate change is coffee. Brazil is the world’s largest coffee producer, with a predominance of management under a conventional system, with sloping terrain and the absence of conservationist practices. The absence of conservationist practices increases in soil loss rates due to water management and carbon emissions, as well as a reduction in coffee production. This paper intended to estimate soil and organic carbon losses by RUSLE in coffee farms in southern Minas Gerais, south-eastern Brazil. Data were obtained from fieldwork, laboratory analysis, and cartographic products. The results indicated, exclusively for coffee crops, soil and carbon losses between 7 and 32 Mg ha−1 year−1 and 87 and 460kg ha−1 year−1, respectively. However, the highest soil losses occurred on sloping terrains with eucalyptus plantations located downhill, and the lowest losses occurred on flat land with native forests. Organic carbon losses were linked directly to soil losses, as a result from the land practices, slope and agricultural management adopted. These results can be used for the planning and priority definition of areas needing conservationist practices, such as green manuring, planting in contour and maintaining of vegetation between coffee rows, which are already used in some sites of the study area. [ABSTRACT FROM AUTHOR]

Approximately a third of all annual greenhouse gas emissions globally are directly or indirectly associated with the food system, and over a half of these are linked to livestock production. In temperate oceanic regions, such as the UK, most meat and dairy is produced in extensive systems based on pasture. There is much interest in the extent to which such grassland may be able to sequester and store more carbon to partially or completely mitigate other greenhouse gas emissions in the system. However, answering this question is difficult due to context-specificity and a complex and sometimes inconsistent evidence base. This paper describes a project that set out to summarize the natural science evidence base relevant to grassland management, grazing livestock and soil carbon storage potential in as policy-neutral terms as possible. It is based on expert appraisal of a systematically assembled evidence base, followed by a wide stakeholders engagement. A series of evidence statements (in the appendix of this paper) are listed and categorized according to the nature of the underlying information, and an annotated bibliography is provided in the electronic supplementary material. [ABSTRACT FROM AUTHOR]

This data paper presents observations on soil organic carbon (SOC) gravimetric and volumetric contents (SOCg, in g kg−1, and SOCv, in g dm−3, respectively) for 98 profiles at least 30 cm deep (1 m deep for 59 of them), in rural areas of the Martinique island, in relation to soil types and land uses and management. The paper also presents particle size distribution down to 30 cm, and near infrared reflectance (NIR) spectra for the main soil types. This dataset allows evaluating the effects of land use, soil type and texture on SOC content and stock, at regional scale. It also allows inferring SOCg, SOCv and particle size distribution from NIR spectra. Such information is useful for studying and managing soils in the Martinique island and in other tropical volcanic regions. [ABSTRACT FROM AUTHOR]

The term carbon (C) sequestration has not just become a buzzword but is something of a siren's call to scientific communicators and media outlets. Carbon sequestration is the removal of C from the atmosphere and the storage, for example, in soil. It has the potential to partially compensate for anthropogenic greenhouse gas emissions and is, therefore, an important piece in the global climate change mitigation puzzle. However, the term C sequestration is often used misleadingly and, while likely unintentional, can lead to the perpetuation of biased conclusions and exaggerated expectations about its contribution to climate change mitigation efforts. Soils have considerable potential to take up C but many are also in a state of continuous loss. In such soils, measures to build up soil C may only lead to a reduction in C losses (C loss mitigation) rather than result in real C sequestration and negative emissions. In an examination of 100 recent peer‐reviewed papers on topics surrounding soil C, only 4% were found to have used the term C sequestration correctly. Furthermore, 13% of the papers equated C sequestration with C stocks. The review, further, revealed that measures leading to C sequestration will not always result in climate change mitigation when non‐CO2 greenhouse gases and leakage are taken into consideration. This paper highlights potential pitfalls when using the term C sequestration incorrectly and calls for accurate usage of this term going forward. Revised and new terms are suggested to distinguish clearly between C sequestration in soils, SOC loss mitigation, negative emissions, climate change mitigation, SOC storage, and SOC accrual to avoid miscommunication among scientists and stakeholder groups in future. [ABSTRACT FROM AUTHOR]

Antioxidants (AOX) in soils originate mainly from secondary plant metabolites and are pivotal in many redox processes in environment, maintaining soil quality. Still, little is known about the influence of land uses on their accumulation in soil. The aim of the paper was to determine the content of these redox-active compounds in the extracts of A horizons of abandoned fallows, arable and woodland soils. Total antioxidant capacity (TAC) of soils under various uses and vegetation was evaluated in different soil extracts using Folin-Ciocâlteu method. The contribution of humic acids to TAC was determined and antioxidant profiles estimated using the chromatographic GC–MS method. Forest soils exhibited the highest TAC (15.5 mg g−1) and AOX contents (4.34 mg g−1), which were positively correlated with soil organic carbon content. It was estimated that humic acids contribute to over 50% of TAC in soils. The main phenolics in woodland A horizons were isovanillic and p-hydroxybenzoic acid (p-HA), while esculetin and p-HA predominated in the abandoned fallows due to the prevalence of herbaceous vegetation. Cultivated soils were the most abundant in p-HA (56.42%). In the studied topsoils, there were considerable amounts of aliphatic organic matter, which role in redox processes should be further evaluated. [ABSTRACT FROM AUTHOR]

With the global climate problem becoming increasingly severe, governments have adopted policies to encourage enterprises to invest in low-carbon technologies. However, the opacity of the carbon emission reduction process leads to incomplete consumer trust in low-carbon products as well as higher supply chain transaction costs. Based on this, this paper constructs Stackelberg game models with and without blockchain under different power structures and compares the impact of these models on low-carbon emission reduction decisions. The results show that: (1) blockchain does not necessarily improve enterprise profits and can only help enterprises maintain optimal profits within a certain range when the carbon emission cost is low; (2) when consumers' environmental awareness is high, the blockchain can incentivize manufacturers to enhance carbon emission reduction, and it has an obvious promotional effect on retailers' profits; and (3) the profit gap between enterprises in the supply chain is larger under different power structures, and the implementation of blockchain can coordinate profit distribution and narrow the gap between enterprises. Compared with the manufacturer-dominated model, the emission reduction in products is maximized under the retailer-dominated model. Our study provides theoretical support for the government to regulate greenhouse gas emissions as well as for the optimization of enterprises' decision-making supported by blockchain. [ABSTRACT FROM AUTHOR]

Mining sector has been the central attention of the business and public policy sustainable development scheme for several years. Reclamation territories are with potential carbon sequestration capacity in degraded mining areas and can be an impeccable option for achieving sustainable development goal-13. This paper made an investigation about the presence of heavy metals in reclaimed area possibilities to improve reclaimed soils with biochar with idea to enhance ecosystem carbon pool and atmospheric CO2 sequestration capacity to offset CO2 emission and soil organic carbon losses. The results show that the carbon content in biochar is 46.6 % and would be classified in class 2 according to the International Biochar Initiative. H/C and O/C atomic ratios could be useful for restoration of degraded poor mine soils through enhanced carbon sequestration. O/C ratio is 0.085 mol mol–1 and half-life of biochar is 2795.65 years, which confirm the biochar stability. For each kilogram of biochar incorporated into the soil, 144 g of carbon were sequestrated 52,8 % CO2 emission reduction. Hence, the biochar developed in this study can be used in carbon-deficient soils with the added benefit of long-term carbon storage. [ABSTRACT FROM AUTHOR]

Background: Grazing lands provide numerous ecosystem services, including the capacity to store large amounts of soil carbon (C); however, our understanding of the factors affecting soil C responses to management is inadequate. Methods: In this paper, we synthesized information about the impacts of grazing land management on soil C within the southeastern region of the United States. Results: Most studies (68%) demonstrated that proper management increased soil C stocks with an average C accumulation rate of 1.4 Mg C ha−1 year−1. The remaining (32%) studies showed no effect of management on soil C. None of the studies reported negative impacts of management on soil C. The largest increase in soil C (8 Mg C ha−1 year−1) was associated with the conversion of cropland to pastureland while overseeding legumes into grass pastures resulted in the lowest C sequestration rates (0.2 Mg C ha−1 year−1). Conclusions: Considering the rates of soil C accretion and the extensive area occupied by grazing lands, data in this synthesis confirm that the adoption of improved management practices can increase soil C sequestration in the southeastern United States. In addition, because most improved management practices can also have co‐benefits, they may be favorable for forage and livestock production and other ecosystem services. [ABSTRACT FROM AUTHOR]

Biochar incorporation into soil has shown potential, in enhancing nitrogen fertilizer (N-fertilizer) efficacy and soil organic carbon content (SOC). This study addresses a critical gap in the literature by investigating the effects of biochar addition over a seven-year period (2014–2020) on inorganic N, SOC, and pH in Haplic Luvisol. The research involved a rain-fed field experiment, with a crop rotation comprising spring barley, maize, spring wheat, and pea. Biochar, applied at the rates of 0, 10, and 20 t ha−1 in 2014, was reapplied to specific plots in 2018. Biochar was also combined with N-fertilizer at three level (N0, N1, and N2). Results showed a significant interactive influence of biochar and N-fertilizer combination on NO3− and NH4+ contents. Intriguingly, the addition of 10 t biochar ha−1 consistently decreased soil inorganic N levels across most of the examined months. Increasing biochar application rates led to a significant rise in pH, establishing a clear, negative correlation between soil pH and inorganic N content. Biochar significantly increased SOC compared to the control, particularly after the reapplication in 2018. However, this effect showed a diminishing trend over time. The study suggests that incorporating biochar treatments may enhance N-fertilizer effectiveness. However, the long-term implications of biochar application with N-fertilizer on N mineralization are specific to individual soil and biochar combinations. Except the application of 20 t ha−1 biochar at N2 in 2019, biochar did not affect the crop yields. Studied soil properties, including those influenced by biochar had nuanced impact on different aspects of crop yield. Article Highlights: Biochar obtained from mixed paper fiber sludge and the grain husks resulted in a significant increase of SOC over 7 years. Biochar aging resulted in a decrease in pH one year after its application in 2015 and 2019. The combination of N-fertilizer with biochar caused an improvement in soil inorganic N content in 2014 and reapplication in 2018. [ABSTRACT FROM AUTHOR]

Soil organic carbon storage is a well-identified climate change mitigation solution. Quantification of the soil carbon storage in cropland for agricultural policy and offset carbon markets using in situ sampling would be excessively costly, especially at the intrafield scale. For this reason, comprehensive monitoring, reporting, and verification (MRV) of soil carbon and its explanatory variables at a large scale need to rely on hybrid approaches that combine remote sensing and modelling tools to provide the carbon budget components with their associated uncertainties at intrafield scale. Here, we present AgriCarbon-EO v1.0.1: an end-to-end processing chain that enables the estimation of carbon budget components for major and cover crops at intrafield resolution (10 m) and regional extents (e.g. 10 000 km 2) by assimilating remote sensing data (e.g. Sentinel-2 and Landsat8) in a physically based radiative transfer (PROSAIL) and agronomic models (SAFYE-CO2). The data assimilation in AgriCarbon-EO is based on a novel Bayesian approach that combines normalized importance sampling and look-up table generation. This approach propagates the uncertainties across the processing chain from the reflectances to the output variables. After a presentation of the chain, we demonstrate the accuracy of the estimates of AgriCarbon-EO through an application over winter wheat in the southwest of France during the cropping seasons from 2017 to 2019. We validate the outputs with flux tower data for net ecosystem exchange, biomass destructive samples, and combined harvester yield maps. Our results show that the scalability and uncertainty estimates proposed by the approach do not hinder the accuracy of the estimates (net ecosystem exchange, NEE: RMSE =1.68 –2.38 gC m -2 , R2=0.87 –0.77; biomass: RMSE =11.34 g m -2 , R2=0.94). We also show the added value of intrafield simulations for the carbon components through scenario testing of pixel and field simulations (biomass: bias =-47 g m -2 , - 39 % variability). Our overall analysis shows satisfying accuracy, but it also points out the need to represent more soil processes and include synthetic aperture radar data that would enable a larger coverage of AgriCarbon-EO. The paper's findings confirm the suitability of the choices made in building AgriCarbon-EO as a hybrid solution for an MRV scheme to diagnose agro-ecosystem carbon fluxes. [ABSTRACT FROM AUTHOR]

The article titled "Correction to 'Cover crops do not increase soil organic carbon stocks as much as has been claimed: What is the way forward?'" by Chaplot and Smith discusses an error in their previous paper regarding the impact of cover crops on soil organic carbon stocks. They maintain their central conclusion that current studies do not provide sufficient reliable data to determine the impact of cover crops on soil organic carbon stocks. They also provide suggestions for future experiments in this area. The article includes a table listing research papers on the impact of cover crops on organic carbon stocks, with details about the authors, publication year, and additional notes about each paper. The authors acknowledge an error in the table and apologize for it. [Extracted from the article]

Background: The study of soil organic carbon characteristics and its relationship with soil environment and vegetation types is of great significance to the evaluation of soil carbon sink provided by inland salt marshes. This paper reports the characteristics of soil organic carbon fractions in 0–50 cm soil layers at four vegetation communities of the Qinwangchuan salt marsh. Results: (1) The soil organic carbon content of Phragmites australis community (9.60 ± 0.32 g/kg) was found to be higher than that of Salicornia europae (7.75 ± 0.18 g/kg) and Tamarix ramosissima (4.96 ± 0.18 g/kg) and Suaeda corniculata community (4.55 ± 0.11 g/kg). (2) The soil dissolved organic carbon, particulate organic carbon and soil microbial biomass carbon in 0–50 cm soil layer of Phragmites australis community were higher, which were 0.46 ± 0.01 g/kg, 2.81 ± 0.06 g/kg and 0.31 ± 0.01 g/kg, respectively. (3) Soil organic carbon was positively correlated with dissolved organic carbon, particulate organic carbon, and microbial biomass carbon, and negatively correlated with easily oxidized organic carbon. (4) Above-ground biomass has a strong direct positive effect on soil organic carbon, total nitrogen and pH have a strong direct positive effect on microbial biomass carbon content, pH and average density have a strong direct negative effect on easily oxidized organic carbon, and particulate organic carbon. Conclusions: The interaction between plant community characteristics and soil factors is an important driving factor for soil organic carbon accumulation in inland salt marshes. [ABSTRACT FROM AUTHOR]

In the quest for a sustainable farming system around the world, organic farming has emerged as the most promising alternative system that can offer solutions to the growing sustainability issues associated with the current input-intensive agriculture system. Organic farming is also becoming increasingly important due to a significant rise in the demand for organic food across the world. Realizing the importance of organic agriculture in the current Indian agricultural scenario, the Government of India has taken several initiatives to promote organic farming across the country. As a result, there has been a considerable increase in different dimensions of organic farming especially in India over the last decade. However, studies have found that organic farming practices in India are more suited to a few specific regions (such as rain-fed zones, low-productivity areas, hills, and arid zones) as compared to the other parts of the country. In this backdrop, this paper attempts to evaluate the state-wise progress of organic farming in India. To measure the inter-state variation in the performance of organic farming, a composite index has been constructed by taking into account four different performance dimensions viz. area covered under organic cultivation, volume of organic production, volume of organic export, and number of producers practicing organic farming. The result suggests a wide disparity in performances in respect of organic farming among the states in India. Interestingly, the states that have performed well in organic farming are found to have a higher level of organic carbon stock in their soil. This shows the influence of agroclimatic conditions on the organic cultivation practices as popularly postulated in the literature. [ABSTRACT FROM AUTHOR]

Aim: The accumulation of microbial necromass carbon has gained increasing attention due to its slow decomposition. However, it remains unclear what induces the accumulation of microbial necromass carbon via reiterated community turnover on large spatial scales. This study explores the characteristics of soil necromass carbon accumulation in terrestrial ecosystems. Location: Global. Time Period: Contemporary (1999–2022). Major Taxa Studied: Soil microorganisms. Methods: A dataset was compiled using 993 observations from 82 peer‐reviewed papers on the effects of coefficients of microbial necromass accumulation (hereafter NAC) in equilibrium. Linear mixed‐effect models and structural equation models were used to ascertain the controlling factors of the NAC. Results: The average NAC was higher in croplands (28.2) and forests (26.8) than in grasslands (21.1). Edaphic factors seemingly affected the NAC, which was lower in soils with high pH and clay content on a global scale. Biotic factors, particularly those related to living microorganism abundance and microbial biomass nitrogen content, were the pivotal drivers of NAC and accounted for approximately 43.6% of its geographic variability. More organic carbon was likely to be preserved in soil with a higher NAC, regardless of ecosystem type. Conclusions: Novel findings regarding the overriding controls for the living microorganism abundance and microbial biomass nitrogen that drive the NAC highlight an urgent need for viable strategies to manipulate microbial attributes for enhancing carbon sequestration. [ABSTRACT FROM AUTHOR]

Soil carbon sequestration is listed by the United Nations Framework Convention on Climate Change as one of the key ways to achieve long-term “carbon neutrality” in the context of global warming. Soil carbon sequestration is a complex biogeochemical process that involves plants, microbes, and rock minerals at its core. Yet, its regulation mechanisms and promotion pathways remain unclear. This paper reviews recent progress in the related domestic and international research and provides an overview of the key processes and mechanisms of soil carbon sequestration. The main pathways for enhancing soil carbon sequestration (including plant inputs, mineral protection, microbial transformation, and rock weathering) are summarized. The paper also discusses and synthesizes how advanced biogeochemical methods and technologies may be employed to explore soil carbon sequestration mechanisms and potentials. The overall aim of this review is to improve our understanding of soil carbon sequestration as a nature-based solution to combatting climate change from the biogeochemistry perspective, and to highlight the role of fundamental research in Earth Sciences in helping to achieve China’s carbon neutrality goals. [ABSTRACT FROM AUTHOR]

Soil structure is a dynamic property which controls a wide range of soil functions and is closely linked with soil carbon content. The carbon contents of agricultural soils are subject to several ongoing trends, including declining carbon stocks and attempts to increase the soil carbon reserves. In this study, we aimed to quantify how organic soil amendments, which have been shown to reduce long-term nutrient loads from agricultural fields, can impact soil structure. The structural impacts of a large one-time addition (8 tons carbon per hectare, three different soil amendments) of pulp and paper mill side stream sludges to a boreal clay soil were explored quantitatively in aggregate (X-ray microtomography, sample size 1–2 mm), core (water retention measurements, sample size 195 cm3) and column (macropores ≥80 µm, sample size ∼ 20 dm3) scales. Our results showed no micrometer-scale structural changes within soil aggregates despite the large number (25 aggregate per treatment) of imaged samples. However, the organic soil amendments had a statistically significant impact on the macroporosity. The macroporosity was on average 20–27 % higher compared to the control samples and visible even five years after the application of the amendments. Such change in soil structure improves soil aeration and fast infiltration of water during wet periods and extreme rain events and may thereby also reduce erosion risk by decreasing surface runoff. The increased microporosity was visible only in the column scale. No statistically significant differences were observed in the fraction of large pores in core scale water retention measurements. Probing the soil structural changes in macropore regime by X-ray tomography or developing sub-micron scale analysis methods are recommended approaches to improve our understanding of clay soil's structural changes induced by organic soil amendments. • The effect of a large single dose of organic matter on soil structure was studied. • Soil structure was investigated from aggregate to column scale. • 100 aggregates imaged with X-ray tomography. • Differences in intra-aggregate porosity were not found. • Only macropores (≥80 µm) were affected by the organic soil amendments. [ABSTRACT FROM AUTHOR]

• Snow coverage alteration has immediate and carry-over impacts on soil C pools. • Snow removal enhances DOC and TOC in spring. • Snow addition enhances soil respiration immediately and in the following summer. • The response of microbial biomass to snow addition was affected by ecosystem type. • Relative change in snow depth determines the extent of snow treatment impacts. Snow distribution has been altered over the past decades under global warming, with a significant reduction in duration and extent of snow cover and an increase in unprecedented snowstorms across large areas in cold regions. The altered snow conditions are likely to have immediate (in winter) and carry-over or legacy (which an extended effect might continue in the following spring, summer and autumn) impacts on soil processes and functioning, but a quantification of the legacy effect of snow coverage alternation is still lacking. Furthermore, studies investigating the effect of snow cover changes on soil respiration, soil carbon pools and microbial activity are increasing, but contrasting results of different studies makes it difficult to assess the overall effect of snow cover changes and the underlying mechanisms, thus a systematic and comprehensive meta -analysis is required. In this study, we synthesized the results from 60 papers based on field snow manipulation experiments and conducted a meta -analysis to evaluate immediate and prolonged effects on eight variables related to soil carbon dynamics and microbial activity to snow coverage alternation. Results showed that snow removal had no significant effect on soil respiration, but increased dissolved organic carbon (DOC) (11.5%) and fungal abundance (32.0%). By contrast, snow addition significantly increased soil respiration (16.3%) and microbial biomass carbon (MBC) (6.6%). Snow addition had immediate and prolonged impacts on soil carbon dynamics and microbial activity lasting from winter to the following autumn, whereas an effect of snow removal on total organic carbon (TOC) and DOC was detectable only in the following spring. Snow depth, ecosystem and soil types determined the extent of the impact of snow treatments on soil respiration, DOC, MBC and microbial biomass nitrogen (MBN). Our findings provide critical insights into understanding how changes in snow coverage affect soil respiration and microbial activity. We suggest future field-based experiments to enhance our understanding the effect of climate change on soil processes and functioning in the winter and the following seasons. [ABSTRACT FROM AUTHOR]

Organic materials are integral to the soil carbon cycle in agricultural ecosystems, yet their specific impacts on soil organic carbon (SOC) and microbial diversity are not fully understood. In this study, we analyzed 188 data pairs from 57 published papers to assess the effects of various organic materials on SOC composition and microbial diversity across different farmlands. Our findings indicate that the addition of organic materials consistently enhances SOC composition and promotes both bacterial and fungal diversity. Notably, the particulate organic carbon (POC) fraction exhibited the most significant increase (42.35%), suggesting that POC is the primary pathway for organic carbon accumulation. Our analysis also identified the type of organic material as the leading factor influencing soil active carbon fractions and microbial diversity, with compost emerging as the most effective material for boosting soil carbon sequestration and microbial richness. Interestingly, while both dissolved organic carbon (DOC) and microbial biomass carbon (MBC) increased with organic material addition, a negative correlation between these two components was observed. This study advances our understanding of the complex interactions between organic materials, SOC components, and microbial diversity, providing valuable insights for the development of sustainable soil management practices aimed at enhancing soil carbon storage and agroecosystem health. [Display omitted] • Organic material enhanced active SOC components and microbial diversity. • Material type is a key determinant of soil carbon composition. • The main factor of SOC increase was the accumulation of POC. • MBC has a potential competition with DOC. [ABSTRACT FROM AUTHOR]

Trade-induced carbon transfer generates significant impacts on global carbon emissions, leading to carbon inequality (CI). This paper introduces a novel indirect metric, the trade-induced domestic carbon share (TDCS), designed to quantify economies' carbon benefits from international trade. Based on data from 17 manufacturing sectors in 66 major economies, this study compares the impact of developed and developing economies' participation in global value chains (GVCs) on TDCS, offering insights into trade-related carbon inequality. Our analysis reveals that GVCs participation by developed economies generally decrease their TDCS, in contrast to an increase in developing economies, thereby exacerbating carbon inequality. Notably, backward participation in GVCs reduces TDCS across all economies, whereas forward participation in GVCs results in increased TDCS in developing economies but a decrease in developed ones. Additionally, our study indicates that developed economies enhance their position in both forward and backward GVCs but experience a decline in the ratio of domestic value added (DVAR). In contrast, developing economies strengthen their forward GVCs position and DVAR but weaken their backward GVCs position. These findings offer new perspectives on carbon inequality in international trade and provide valuable guidance for policymakers in devising industrial trade and carbon reduction strategies. [ABSTRACT FROM AUTHOR]

Irrigation can increase crop yields and could be a key climate adaptation strategy. At present, under the background of increasing food demand and continuous expansion of irrigation cropland, there still uncertainties about the soil carbon dynamics under the change of irrigation water volume and irrigated area in view of large-scale spatial heterogeneity. Therefore, this paper uses space-for-time + meta-analysis and a two-step methodology based on the residual trend analysis to quantitatively analyze the relationship between soil organic carbon (SOC) and soil respiration (Rs) in response to fluctuations in irrigation water volume and irrigated land extents. Here we show that the irrigation water volume within 100–1000 mm had a negative impact on SOC, and the impact was correlated with the irrigation water volume. Different levels of irrigation water manifest distinct effects on SOC content across varying soil depths. When irrigation water quantities are less than 700 mm, the impact on SOC content in the 0–30 cm depth layer surpasses that in the 30–200 cm depth layer. Conversely, when irrigation water quantities equal or exceed 700 mm, this pattern is reversed. The overall impact of irrigation on SOC stock at a depth of 0–200 cm was −14.88±6.7%. Tillage, planting intensity, topography, and soil type within irrigated cropland all exert variable impacts on SOC content. Whether these influences are deleterious or beneficial hinges predominantly upon the balance between the augmentation of SOC stock due to heightened carbon inputs from crops and the reduction of SOC through alterations in microbial activity. Mann-Kendall trend analysis showed that from 2000 to 2015, the overall Rs of cropland showed an increasing trend, with an increase rate of 3.67 g/m2/year. The increase of global Rs is mainly driven by climate change factors (temperature, precipitation and solar radiation), while the decrease of Rs in a small number of areas is mainly driven by management practices (fertilizer nitrogen, irrigation, and tillage). Our study further quantifies the impact of irrigation on soil carbon dynamics, thereby offering potential pathways and data support for the advancement of sustainable agriculture. • Developed an approach that integrates space-for-time with meta-analysis. • Quantifying soil carbon dynamics under changes in irrigation water volume and irrigated area at the global scale. • Irrigation had a negative impact on SOC, and the impact was correlated with the irrigation water volume. • From 2000–2015, the global increase in soil respiration of irrigated croplands was mainly caused by climate change. [ABSTRACT FROM AUTHOR]

With the establishment of carbon peaking and carbon neutrality goals in China, developing low-carbon cities has become crucial. Previous studies primarily focus on the quantitative structure of land use to achieve low carbon optimization, while ignoring the spatial integration between urban form and carbon emissions. To fulfill this gap, this paper proposed a dual-scale low carbon oriented multi-objective land use allocation (DOLA) optimization model, utilizing idea-point multi-objective linear programming (IMLP) and non-dominated sorting genetic algorithm II (NSGA-II) to optimize the low-carbon-emission pattern of the city at both the structural and spatial scales respectively. By innovatively linking the urban shape index with carbon emissions, this model aims to minimize urban carbon emissions, while maximizing economic development, urban development suitability, and the compactness of city. The proposed method is applied to Wuhan's main urban area in China, the DOLA model shows significant improvements in target values across all scenarios. Among them, the scenario that prioritized low carbon emissions at both the structural and spatial scales achieved the most significant reduction of 6.43 % in carbon emissions. The DOLA effectively contributes to achieving multiple spatial targets, thereby aiding in reducing carbon emissions. It offers technical support for developing pathways towards China's "dual carbon" target. • A dual-scale low carbon oriented multi-objective land use allocation (DOLA) optimization model is proposed. • The DOLA model innovatively incorporates urban form indices to carbon emissions. • The DOLA model achieves spatial aggregation targets, thereby facilitating significant reductions in carbon emissions. • The DOLA model generates a series of land use optimization scenarios, offering a valuable reference for land use planning. [ABSTRACT FROM AUTHOR]

Steel is the most common industrial material worldwide due to its numerous applications, high strength and recyclability. Steel production involves alloying iron with various amounts of carbon and other elements to produce thousands of different grades and types of steel for various purposes. However, the intensive use of carbon in steel production is one of the factors contributing to global climate change. To use of hydrogen and renewable energy sources in steel production has emerged as a significant solution to reduce carbon emissions. The aim of this study is to obtain green hydrogen for the production of green steel. The focus is on utilizing offshore wind energy as a renewable energy source to give us the energy we need to electrolyze seawater. The study uses the seas of Turkiye for case analysis. In this paper, an integrated Multi-criteria decision-making method is used to integrate hybrid energy systems and their application for green industry and to select a location for a power generation plant. The study is a new contribution to the literature in terms of its scope. Green steel's location selection is addressed for the first time in the literature. The weights of the criteria are determined by employing the Best-Worst Method (BWM) as a multi-criteria decision-making technique, and the alternatives are evaluated using the Analytic Hierarchy Process (AHP). By using the BWM method, decision makers can have a clear understanding of the evaluation range for pairwise comparisons of criteria, which reduces potential biases. According to the study, the northern part of the Aegean Sea in Turkiye is the most suitable alternative for green steel production, with offshore wind energy being used for hydrogen production. The study also revealed that the most important main criterion for this hybrid system is "natural factors", and the sub-criteria are "wind speed and power density" by far compared to other sub-criteria. The fact that the area determined for the facility is suitable for construction and the possibility that the customer of the energy produced is other industrial establishments here is the most important indicator that the methods applied give good results. [ABSTRACT FROM AUTHOR]

• The net ecosystem carbon balance was extended for harvest residues (HR). • The balance term related to HR can be in the range of other cumulative carbon terms. • Therefore, it is imperative to consider HR in the carbon balance of croplands. • Soil carbon loss/gain are mostly controlled by the fast-decomposing carbon pools. Over the past two decades, major efforts have been made to quantify the extent to which and under what conditions croplands are sources or sinks for carbon. For this purpose, the net carbon stock change of the study site is typically quantified based on net CO 2 fluxes monitored with an eddy covariance or chamber system, on measured C import by organic fertilizer and C export by harvest. While in cropland studies this balance is usually referred to as net biome productivity (NBP), we prefer to use the term net ecosystem carbon balance (NECB) here. NECB is basically the sum of the stock change of plant carbon (ΔPC) and soil organic carbon (ΔSOC). In the standard approach, the assumption is that at an annual cropland site the bulk of plant biomass is typically removed at harvest, and that ΔPC can therefore be neglected. In this case, ΔSOC equals NECB. In this paper we show that this assumption is problematic, particularly if in crop rotation systems the budget is determined over a single cropping period. The present contribution extends the concept of NECB to include harvest residues (HR) and applies it to a case study over a maize - winter wheat - winter wheat rotation at a cropland site in southwest Germany. In all three cropping periods, the sign of NECB was opposite that of ΔSOC. Accordingly, neglecting HR led to an incorrect result concerning the question whether the site is a sink or a source for soil carbon. Our findings demonstrate that for croplands HR must be included to obtain an accurate and meaningful carbon balance. [ABSTRACT FROM AUTHOR]

Conservation tillage has a profound impact on soil organic carbon (SOC) and extracellular enzyme activity (EEA), thereby influencing the global soil nutrient cycle. However, there is currently a lack of comprehensive understanding regarding the key factors influencing changes in SOC and EEA, as well as their correlations. To address this gap, a meta-analysis was conducted using data from 78 published papers, encompassing 2005 comparisons from around the world. The goal was to quantify the effects of conservation tillage on SOC and EEA while assessing the effect sizes of categorical variables. The meta-analysis results revealed that conservation tillage significantly increased SOC and carbon (C)-, nitrogen (N)-, phosphorus (P)-, and sulfur (S)-related enzyme activities, with effect sizes of 1.34, 1.57, 1.50, 1.06, and 1.81, respectively. Additionally, conservation tillage resulted in a decrease in soil pH compared to conventional tillage. Furthermore, significant correlations were found between changes in SOC and N-, P-, and S-related enzyme activities. However, only β-glucosidase (βG) and β-xylosidase (βX) in C-related enzyme activities were found to be relevant to SOC. Moreover, the results from the structural equation model indicated that several factors directly influenced the EEA of C-, N-, P-, and S-related enzymes. Climatic factors such as latitude and mean annual temperature (MAT), agronomic practices (including fertilization and tillage duration), and soil properties (such as soil depth), were identified as having direct effects on the EEA of the respective enzymes. From a global perspective, conservation tillage was observed to enhance the potential activity of C-related enzymes, while the balanced activity of N-, P-, and S-related enzymes requires greater attention. Additionally, latitude, MAT, fertilization, tillage duration, and soil depth emerged as important aspects requiring careful consideration in the development of management strategies for conservation tillage. • Conservation tillage could improve most extracellular enzyme activity but not all. • Soil organic carbon stocks influenced most EEA under conservation tillage. • Factors affecting changes in SOC and EEA under conservation tillage was explored. • The potential of improving C-related enzyme activity is better than the others. [ABSTRACT FROM AUTHOR]

• Soil reflectance composites were generated with Sentinel-2 L2A data. • A multi-channel CNN learning framework for soil organic carbon prediction is proposed. • A dual input deep learning architecture improves the predictions. • The framework produced results that can be interpreted. The Copernicus Sentinel-2 multispectral imagery data may be aggregated to extract large-scale, bare soil, reflectance composites, which enable soil mapping applications. In this paper, this approach was tested in the German federal state of Bavaria, to provide estimations for soil organic carbon (SOC). Different temporal ranges were considered for the generation of the composites, including multi-annual and seasonal ranges. A novel multi-channel convolutional neural network (CNN) is proposed. By leveraging the advantages of deep learning techniques, it utilizes complementary information from different spectral pre-treatment techniques. The SOC predictions indicated little dissimilarity amongst the different composites, with the best performance attained for the six-year composite containing only spring months (RMSE = 12.03 g C · kg−1, R2 = 0.64, RPIQ = 0.89). It has been demonstrated that these outcomes outperform other well-known machine learning techniques. An ablation analysis was accordingly performed to evaluate the interplay of the CNN's different components to disentangle the advantages of each aspect of the proposed framework. Finally, a DUal inPut deep LearnIng architecture, named DUPLICITE, is proposed, which concatenates deep spectral features derived from the CNN mentioned earlier, as well as topographical and environmental covariates through an artificial neural network (ANN) to exploit their complementarity. The proposed approach was demonstrated to provide an improvement in the overall prediction performance (RMSE = 11.60 gC · kg−1, R2 = 0.67, RPIQ = 0.92). [ABSTRACT FROM AUTHOR]

• Tree richness and mycorrhizal-symbionts effects on SOC, GRSP-C, Rh, Q 10, Hs and GHGs were studied. • High tree richness induced 16–126.6% higher SOC, TG-C, Rh, and in situ N 2 O flux. • AM dominant plots had 34–39% higher SOC and Rh than the ectomycorrhizal plots. • Richness and AM's effects in 0–1 m soils were more evident than 0–20 cm soils. • Richness directly improved stability, while richness-AM-decreased-CAZymes favoured storage accrual. • Six types of CAZymes of GHs, PLs, CEs, GTs, AAs and CBMs cooperatively worked in the regulation. Biodiversity loss and tree alternations often occurred in high-latitude Northern Hemisphere forests owing to climatic changes and human disturbance, while their effects on soil carbon sequestration remain unclear. In this paper, tree richness and arbuscular mycorrhizal (AM)-tree dominance experiments were settled in an experimental forest, and soil organic carbon (SOC) and glomalin-related soil protein carbon (Total, TG-C and easily extracted, EEG-C), stability (heterotrophic respiration, Rh, temperature sensitivity, Q 10 and humidity sensitivity, Hs), in situ soil CO 2 , CH 4 , N 2 O fluxes, and CAZymes activities from the microbial metagenome technique were measured to identify their impacts and underlying mechanism. Both analysis of variance (ANOVA) and linear regression found tree richness and AM tree loss accompanied by soil carbon sequestration loss of total SOC storage, their mycorrhizal components (TG-C) and Rh. In 0–20 cm soils, high tree richness quadrats had 16–126.6 % higher SOC, TG-C, Rh, and in situ N 2 O flux, while AM-dominated stands had 34–39 % higher SOC and Rh than the EcM-dominated stands. In the 1 m soil profile, the effect size from tree richness and AM trees were more evident than the 0–20 cm soils. Compared with the richness gradient, much significant differences occurred between AM- and EcM-dominated stands. Structural equation modeling found that tree richness directly improved C stability, while the SOC accrual from the tree richness enrichment and AM-tree dominance were indirectly achieved by their decreasing in multiple CAZymes activities. Of CAZymes, glycoside hydrolases, polysaccharide lyases, carbohydrate esterases, glycosyl transferases, auxiliary activities, and carbohydrate-binding modules cooperated in their regulation of the soil C accrual. Our findings support carbon sequestration via biodiversity conservation and proper forest management related to tree mycorrhizal symbionts. [ABSTRACT FROM AUTHOR]

• Solved the lack of spatial features of HSI in predicting soil carbon content. • Proposed multi-scale spectral feature network to extract spectral feature of HSI. • Proposed multi-scale spatial and spectral feature network to extract feature of HSI. • Proposed methods improve the accuracy and stability of soil carbon content prediction. Soil carbon content prediction based on hyperspectral images can achieve large-scale spatial measurement, which has the advantages of wide coverage and fast information collection, is more suitable for field data collection. However, the research on soil carbon content prediction based on hyperspectral images mainly focuses on feature extraction of spectral information, ignoring the spatial information, and cannot well reveal the intrinsic structural characteristics of data. Aiming at the lack of spatial features consideration in hyperspectral images, soil carbon content prediction methods based on multi-scale feature fusion are proposed by hyperspectral image. At the same time of extracting spectral features from hyperspectral images, the spatial information is used for the first time and a multi-scale spectral and spatial feature network (SpeSpaMN) is designed. In the SpeSpaMN, the multi-scale spectral feature network (SpeMN) is constructed to extract spectral features, the multi-scale spatial feature network (SpaMN) is constructed to extract spatial features. The two networks are fused by using the complementary relationship between different scale features to achieve soil carbon content prediction based on multi-scale feature fusion. The results showed that SpeSpaMN had the best results compared to other methods, followed by the method of SpeMN. The RPD of Inland, Aoshan Bay and Jiaozhou Bay samples based on SpeSpaMN were increased by 47.36%, 37.96% and 4.30% respectively. This paper can effectively solve the problem of the deep fusion of spatial and spectral features in the soil carbon content prediction by hyperspectral image, so as to improve the accuracy and stability of soil carbon content prediction. [ABSTRACT FROM AUTHOR]

China's 'dual carbon' strategy is of strategic importance in leading global climate governance and promoting China's high-quality and green economic development. Cities are the centres of human activities. However, these are also places where high energy consumption and high carbon emissions are concentrated. This study selected data from 192 small and medium-sized cities in mainland China for the period 2000–2020. It classified these into seven categories using the K-means clustering method, calculated the decoupling status of different types of small and medium-sized cities based on the Tapio decoupling index, and analysed the relationship between carbon emissions and economic growth in various types of small and medium-sized cities based on the EKC curve theory. Finally, the backpropagation neural network (BPNN) model was used to classify and predict the time required to achieve carbon peaking for seven types of small and medium-sized cities. The following conclusions were drawn: (1) The development status of small and medium-sized cities shows a 'geese echelon pattern'. New dynamic small and medium-sized urban areas may reach peak carbon emissions first, while resource-based small and medium-sized urban areas may be the last to do so. (2) The decoupling of carbon emissions from industrial development in small and medium-sized cities has not been completed. This manifests mainly through the states of declining decoupling, absolute decoupling, and strong negative decoupling. (3) A significant inverted U-shaped relationship exists between economic development and carbon emissions in these cities. (4) These cities may have the disadvantage of premature or excessive de-industrialisation. Additionally, these generally have an inefficient and expansionary economic development status. Therefore, this study contended for a more robust integration of a radical political economy and ecological economics to support the development of such cities in China. The paper proposes differentiated development paths and fundamental recommendations for small and medium-sized cities in the implementation of the 'double carbon' strategy. The intention is to provide theoretical guidance and implications for promoting green and low-carbon development in urban and rural areas and for the early achievement of the strategy in China. [ABSTRACT FROM AUTHOR]