The intensification of livestock farming systems can pose significant environmental challenges, including impacts on soil physicochemical properties, carbon sequestration, and biodiversity. This study is the first to quantify the combined effects of dairy system intensification and land-use allocation on soil organic carbon (SOC) stocks and physicochemical properties at the commercial farm scale. We compared confinement and pasture-based systems across five land-use types: improved pasture (IP), mixed pasture-cropping (MPC), cropping, tree areas (TA), and natural pasture (NP, exclusive to pasture-based systems). A total of 810 soil samples were collected from the top 30 cm across nine farms in New South Wales, Australia. Pasture-based farms stored 75% more SOC and 65% more total nitrogen (TN) per hectare than confinement farms, although differences were partly influenced by regional climate and parent material. Interactions between farming system and land use showed that SOC and TN stocks were highest in IP and TA within pasture-based systems. Conversely, total phosphorus (TP) stocks were 3.7 times higher in confinement systems, independent of SOC patterns. Within pasture-based farms, NP consistently had the highest SOC and TN stocks. These results highlight that dairy system intensification interacts with land-use and environmental conditions to shape soil organic carbon and nutrient stocks. The findings provide policy-relevant benchmarks for soil‑carbon accounting and emphasize the need for regionally adapted land-management strategies and future work quantifying annual SOC sequestration rates under commercial dairy conditions. • First farm-scale assessment of dairy intensification effects on soil properties. • Pasture-based systems store more soil carbon and total N than confinement farms. • Tree areas and natural pastures act as strong soil carbon hotspots. • Soil carbon land-use differences lessen in low-rainfall confinement regions. • Findings support better policy and soil‑carbon accounting for dairy systems.

Modeling soil organic carbon stocks and changes in agricultural cropping systems using a decision support tool and process-based model.

Effects of salinity management practices on the soil organic carbon stock in China's salinized soils: A meta-analysis

Forest ecosystems play an important role in climate change mitigation through carbon storage in biomass and soils. However, information on species-specific carbon sequestration in Mediterranean forests is still limited. This study evaluated biomass accumulation and carbon sequestration capacity of three native Mediterranean tree species (Quercus coccifera, Pinus halepensis, and Ceratonia siliqua) across different developmental stages, including young seedlings (1–3 years) and mature stands (20–80 years), in northern Jordan. Young seedlings were assessed using destructive biomass sampling, while mature stands were evaluated using species-specific allometric equations based on diameter measurements and soil carbon analyses. In addition, seedling and mature-tree evaluations were conducted under different environmental conditions. Carbon concentration varied significantly among plant organs, with generally higher values in leaves than in stems and roots. During early growth stages, young seedlings of C. siliqua exhibited greater annual carbon sequestration (0.55 kg tree−1year−1) than Q.coccifera and P.halepensis (0.1–0.2 kg tree−1 year−1). In mature stands, P.halepensis showed the greatest aboveground carbon storage, reaching approximately 588 kg C tree−1. Soil organic carbon stocks across the 0–60 cm soil profile varied among species, ranging from 17.9 kg m−2 under Q.coccifera to 24.1 kg m−2 under C.siliqua. Annual carbon sequestration rates derived from short-term field observations and allometric biomass estimations (including both above- and belowground components) differed markedly among species. P.halepensis showed the highest sequestration rate (>65 kg tree−1 yr−1), followed by Q.coccifera (∼23–24 kg tree−1 yr−1), whereas C.siliqua exhibited substantially lower rates (<5 kg tree−1 yr−1). These findings suggest that carbon sequestration capacity in Mediterranean forests varies with species, growth stage, and environmental conditions. This variability highlights the need to consider both species selection and site characteristics when designing restoration and afforestation programs aimed at maximizing long-term carbon storage and climate change mitigation in dryland ecosystems.

Understanding how soil carbon pools respond to contrasting land use systems is essential for evaluating soil functioning and land sustainability. Here, we examined the response of total organic carbon (TOC), oxidizable carbon fractions, microbial biomass carbon (MBC), soil organic carbon (SOC) stocks, and the carbon management index (CMI) across four contrasting land use types (forest, orchard, cropland, and abandoned land) at two soil depths (0-10 and 10-20cm) in a sub-humid watershed. Oxidizable carbon fractions were grouped into active pools (very labile + labile) and passive pools (less labile + non-labile). Forest soils showed the highest TOC and MBC, whereas conversion to cropland and abandoned land reduced surface TOC by 36.0% and 47.4%, respectively, and MBC declined markedly under non-forest uses. Surface SOC stocks also decreased by 30.8% in cropland and 41.3% in abandoned land relative to forest. Active carbon pools declined substantially in the 0-10cm layer, with reductions of 50.0% in cropland and 45.2% in abandoned land, while passive fractions accounted for a greater proportion of total SOC under these land uses, indicating a shift toward more stable carbon forms. CMI values further highlighted relative differences in SOC status among land uses: at 0-10cm, CMI was 85.05 in orchard, 56.18 in abandoned land, and 44.16 in cropland, while at 10-20cm the corresponding values were 77.25, 40.28, and 63.99, respectively. Integrating SOC fractionation with CMI provides a useful comparative framework for detecting relative changes in soil carbon status across contrasting land use systems.

BackgroundUnderstanding the vertical distribution and storage of soil organic carbon (SOC) in arid coastal salt marshes is essential for assessing their role in blue-carbon sequestration. This study examines SOC patterns in marshes dominated by Arthrocnemum macrostachyum, Halocnemum strobilaceum, and Salicornia fruticosa, as well as unvegetated areas. Using 200 soil cores (2,000 samples), we applied allometric, exponential, and sigmoid models to predict volumetric SOC density (SOCv; kg C/m³) and cumulative SOC stocks (SOCc; kg C/m²) across depth profiles.ResultsSOC content showed an inverse exponential relationship with soil bulk density across vegetation types, consistent with patterns documented in other salt-marsh and coastal wetland systems. The allometric model provided the best SOCv predictions for A. macrostachyum, whereas the sigmoid model performed best for H. strobilaceum, S. fruticosa, and unvegetated sites, based on mean normalized average error (MNAE), mean normalized bias (MNB), and residual mean squares (RMS). All three models accurately reproduced SOCc for within-core depth extrapolation, with no significant differences between measured and predicted values within the validation dataset.ConclusionsThis study provides an improved understanding of SOC dynamics in arid coastal salt marshes and demonstrates the utility of depth-based mathematical models for predicting SOC storage. These findings support local-scale efforts to evaluate carbon-sequestration potential, though broader spatial validation across heterogeneous landscapes remains necessary.Supplementary InformationThe online version contains supplementary material available at 10.1186/s12870-026-09221-2.

Soils have been proposed as a tool to reduce atmospheric carbon dioxide (CO2). However, sparse field data and soil databases that do not account for geomorphic controls on soil properties hinder accurate quantification of soil organic carbon (SOC) dynamics at the watershed scale. In mountainous terrain, relict landslide deposits are common and feature thick (>5 m), weathered profiles with substantial SOC below the typically measured top 30 cm of soil. We generated a SOC-age relationship using a landslide chronosequence in Western Oregon where these landforms are abundant. We applied our relationships to an inventory of nearly 10,000 previously dated landslides and show that deep SOC stocks constitute ~70% of the total stock for landslides >41.8 thousand years. Our findings also show that SOC stocks associated with deep-seated landslides are >2× larger than estimates from a global model that does not account for geomorphic controls. These results suggest that geomorphology can improve our ability to quantify SOC stocks and could inform watershed management.

Soil organic carbon in Ultisol landscapes: Influence of erosion rates, soil development, depth, and hillslope properties

Spatial variability and drivers of soil organic carbon burial in the tidal flats of the Yellow River Delta

Microplastics influence organic carbon depletion in macroaggregates and soil structural stability in the Yanhe catchment

Soil organic carbon sequestration potential and constraints in arid farmland under climate change: Evaluation based on an optimized process-based model.

Organic amendments alleviate SOC loss from erosion-prone sloping farmland by enhancing physical protection and chemical stabilization.

Spatial prediction of soil organic carbon stocks using regression kriging to support land degradation neutrality (SDG 15.3.1) in Negele Arsi District, Ethiopia

Understanding the spatial variability and environmental drivers of soil organic carbon (SOC) is critical for improving carbon management in fragile karst landscapes. This study collected 110 topsoil samples across county Yangshan, southern China, and applied an interpretable machine learning framework combining Random Forest (RF) and SHapley Additive exPlanations (SHAP) to explore the spatial heterogeneity and key environmental controls of SOC. The measured contents ranged from 3.33 to 44.20 g/kg, with a coefficient of variation of 43.5%, indicating moderate variability. RF-based spatial predictions revealed that higher SOC levels were mainly concentrated in the northern and southern subregions associated with clastic rocks, while lower SOC values clustered in central areas dominated by carbonate bedrocks. SHAP analysis indicated that soil physicochemical properties contributed over 53% to SOC, with total nitrogen and cation exchange capacity exerting the strongest influences, particularly in karst zones. Hydrological, vegetation, and terrain-related factors showed moderate importance, especially in high-elevation areas with natural vegetation and complex topography that promoted SOC accumulation. In contrast, climatic variables had relatively weak impacts, with their influences clustered in lowlands dominated by anthropogenic land uses. These findings revealed spatially heterogenous controls on SOC between karst and non-karst landscapes, emphasizing the dominant role of soil properties under shallow, erosion-prone conditions and highlighting the role of topography and vegetation in enhancing SOC stocks in mountainous areas. The integrated use of interpretable machine learning approaches improves the understanding of localized SOC dynamics and provides a valuable reference for precision carbon management and ecological restoration in other environmentally sensitive regions. • RF-SHAP framework effectively identified key environmental drivers on SOC. • Local SHAP values visualized spatial heterogeneity in karst and non-karst areas. • TN and CEC dominated contributions of SOC, especially under karst landscapes. • Hydrology, vegetation, and terrain influenced SOC in high-elevation clastic zones. • Climatic impacts clustered in lowlands associated with anthropogenic disturbance.

Arctic deltas are highly dynamic environments at the land-ocean interface that have acted as long-term sinks of sediment, carbon (C), and nitrogen (N). Climate impacts Arctic deltas and their upstream catchments through sea-level rise, altered river discharge, increased sediment fluxes, intensified biogeochemical cycling, and permafrost thaw. As a result, soil C and N in Arctic delta deposits are becoming more bioavailable. Here, we present a C and N inventory for Arctic delta compiled from over 1600 soil samples spanning 17 river deltas. We estimate that Arctic delta deposits store 57.5 ( + 9.2/-8.2) Pg C and 3.8 ( + 0.8/-0.7) Pg N across a combined area of nearly 100,000 km², representing large and potentially vulnerable biogeochemical pools. Our findings underscore the potentially pivotal role of Arctic deltas in the pan-Arctic carbon cycle and highlight their importance as dynamic zones of both C and N storage and release in a rapidly changing Arctic.

The global livestock sector produces vast quantities of organic waste that, if managed poorly, represent a significant environmental liability. If appropriately valorised, however, animal waste constitutes a renewable feedstock capable of rebuilding soil organic matter, improving soil biological activity, and supplying essential plant nutrients. This review synthesises current evidence on the principal valorisation processes—composting, vermicomposting, anaerobic digestion with digestate application, and pyrolysis to produce biochar—examining how each pathway transforms raw animal waste into soil amendments with measurable agricultural benefits. The literature search was conducted across multiple bibliographic databases, including Web of Science, Scopus, PubMed, and Google Scholar, which were selected for their broad disciplinary coverage and comprehensive indexing of peer-reviewed journals. Evidence drawn from meta-analyses, field experiments, and process-level studies demonstrates that manure-derived amendments consistently increase soil organic carbon stocks, stimulate microbial biomass, improve soil aggregate stability, and support crop productivity, though the magnitude of these effects varies markedly with amendment type, application rate, soil characteristics, and climate. The review also addresses the principal risks associated with valorised animal wastes, namely the dissemination of antibiotic resistance genes and antimicrobial-resistant bacteria, accumulation of potentially toxic metals, and the potential for elevated greenhouse gas emissions from poorly managed applications. These risks are contextualised within the circular bioeconomy framework, which positions animal-waste valorisation as a mechanism for closing nutrient loops and reducing dependence on energy-intensive synthetic fertilisers. The review concludes by identifying critical knowledge gaps and emerging research priorities, particularly in the governance of digestate quality, struvite production at scale, and the long-term fate of recalcitrant biochar carbon in diverse soil types.

Seagrass ecosystems play a crucial role in coastal carbon dynamics, yet their contribution to soil organic carbon (SOC) storage is underexplored in many areas and especially in African waters. This study assessed seagrass cover, species composition, and SOC stocks in the Lamu Archipelago, Kenya, comparing Marine Protected Areas (MPAs), Locally Managed Marine Areas (LMMAs), and unmanaged sites. Additionally, it investigated the relationships between management stratgeies and pertinent physical and chemical parameters. SOC was measured using the Loss on Ignition method and expressed as Mg C ha⁻¹. SOC stocks were higher in MPAs (89.16 ± 30.88 Mg C ha⁻¹) than in unmanaged areas, while SOC stocks in LMMAs were comparable to those in MPAs. While the MPA was associated with higher SOC stocks, these patterns may also reflect underlying environmental differences among sites, including sediment texture. SOC variability was strongly associated with sediment type, canopy cover, and disturbance intensity, with fine-grained sediments, particularly clay, linked to enhanced carbon retention. Higher SOC stocks co-occurred with the presence of large, persistent seagrass species such as Thalassodendron ciliatum and Enhalus acoroides in managed areas. This study provides the first field-based SOC estimates for Lamu's seagrass meadows, highlighting the potential of LMMAs within broader blue carbon conservation strategies.

Environmental drivers on particulate and mineral-associated organic carbon storage across land use systems in the Brazilian Cerrado region.

Enset-based farming systems are promoted as a sustainable land management strategy in Ethiopia, yet comprehensive evidence of their contribution to soil fertility remains limited. This study assessed the role of three Enset-based farming systems (Enset-dominated, Enset-coffee, and Enset-coffee-fruit based farming) in improving soil fertility compared to adjacent croplands in central Ethiopia. A total of 60 composite soil samples were collected from 0-20 cm and 20-40 cm soil depths across 30 paired plots. Standard laboratory methods were used to analyze soil physicochemical properties, and soil organic carbon stocks were calculated. Statistical analyses included one-way ANOVA, Fisher's LSD post-hoc test, and paired t-tests. Results showed that Enset-based systems had significantly higher (p < 0.05) soil organic matter, total nitrogen, and exchangeable bases (Ca2+, K+, and Mg2+) compared to adjacent croplands at both soil depths. Enset-based systems have significantly higher cation exchange capacity and base saturation at 0-20cm depth compared to adjacent croplands. Most notably, soil organic carbon stocks in Enset with coffee (137.8 ± 27.3 Mg ha-1) and Enset with coffee-fruit (127.3 ± 19.2 Mg ha-1) systems were significantly higher (p < 0.05) than in adjacent croplands (93.5 ± 15.8 and 92.3 ± 16.5 Mg ha-1, respectively). However, soil organic carbon stocks in Enset-dominated systems did not vary significantly from those in croplands. We conclude that integrated Enset-based farming systems, particularly those incorporating perennial crops, substantially enhance soil fertility and carbon sequestration. These findings support policy integration of Enset-based farming systems as climate-smart agricultural practices for sustainable land management in the Ethiopian highlands.

ABSTRACTThere are high expectations that agricultural practices can mitigate climate change and improve soil health by increasing soil organic carbon (SOC) stocks. However, existing large scale SOC monitoring treats agricultural management as a black box, meaning that observed patterns and trends cannot inform on the option space of agricultural practices to improve or deteriorate SOC stocks. Here, we combine for the first time management data from large scale systematic farm surveys (n = 248,362 farms) and representative soil monitoring data (n = 8834 locations) to quantify the impact of agricultural practices on three SOC metrics across all pedoclimatic zones of Europe (EU + UK): stocks, stocks relative to pedoclimatic benchmarks, and yearly change in SOC concentration. Our findings show that in arable and tree crops, but not in grasslands, management intensity is a significant contributor to SOC loss, with impact varying by soil and climate region. However, we also observed that several practices (e.g., high share of manure, organic management, and a high proportion of leys in crop rotation) demonstrated potential for increasing SOC stocks. Under a scenario where all agricultural land in Europe would be managed as that of the 10% most optimally managed farms in terms of SOC benefit, SOC stocks would increase by 1.58 Pg C across Europe (95% CI: 1.27–1.89 Pg C). Whereas under a scenario where farms are managed as the 10% least optimally managed farms, SOC would decrease by −0.92 Pg C (−1.15 to −0.68 Pg C). However, it is important to note that these estimates reflect steady‐state SOC stocks only (i.e., they do not represent the transient build‐up or loss over time, or interactions with a changing climate). This paper thus quantifies how agricultural practices influence patterns in SOC stocks at the continental scale, identifying leverage points for site‐specific policies to improve SOC stocks.