Search Results (1,006)

The soil of Siraitia grosvenorii (LHG) farmland often suffers from acidification, compaction, and declining organic matter content. As biochar helps improve soil quality and enhance soil carbon sequestration capacity, an increasing number of studies are utilizing biochar for soil quality improvement. To address the soil degradation problem in LHG farmland and achieve the goals of soil organic carbon (SOC) sequestration and nutrient increase, we conducted a 100-day indoor constant-temperature incubation experiment by adding different proportions of LHG vine biochar. We analyzed the changes in SOC mineralization, different carbon fractions, and soil nutrient content in LHG farmland. The main results showed that, compared with the control group, the cumulative mineralization (CumulMine) of SOC increased by 3% to 51%, and organic carbon content increased by 52.43% to 193.87%. As the LHG vine biochar application rate increased, the metabolic entropy (qCO₂) rose, whereas the microbial entropy (qMBC) showed an opposite trend. Similarly, compared with the control group, the addition of 1.0%, 2.0%, and 4.0% LC increased water-soluble organic carbon by 45.87 mg·kg⁻¹, 67.00 mg·kg⁻¹, and 81.73 mg·kg⁻¹, respectively, and soil nutrients also increased, but microbial biomass carbon (MBC) and readily oxidizable organic carbon (ROC) contents decreased. The main conclusions indicate that adding LHG vine biochar increases SOC content, which is associated with reduced microbial activity. Biochar-derived DOC may serve as a substrate for microbial respiration, thereby contributing to increased CO₂ release and accelerated nutrient release. The application of LHG vine biochar enhanced the carbon sequestration capacity of LHG farmland soil while improving soil nutrient content, with the 4% application rate treatment performing the best. Full article

Microbial necromass carbon (MNC) is recognized as an important and relatively stable component of soil organic carbon (SOC); however, it is often overlooked and poorly understood in soil management practices, particularly in the context of Loess Plateau farmlands. Here, a 13-year field experiment was carried out to examine the differences in MNC distribution, the role of MNC in SOC storage, and the impact of environmental factors under long-term mulching practices. The experiment used four treatments: (1) no mulching (NT), (2) straw mulching (NSM), (3) plastic mulching (NPM), and (4) ridge mulching (NRM). Compared to NT, all mulching methods increased SOC levels, phospholipid fatty acids (PLFAs), and amino sugar (AS) content. Straw mulching enhanced microbial biomass carbon (MBC), reduced the gap in AS content between rhizosphere and non-rhizosphere soils, and significantly increased MNC. Conversely, NPM and NRM primarily increased MBC and MNC within the rhizosphere soil. Generally, the rhizosphere soil had higher AS content than non-rhizosphere soil. However, regarding the proportion of MNC contributing to SOC, non-rhizosphere soil showed a significantly greater contribution than rhizosphere soil (p < 0.05). The contribution of MNC to SOC ranged from 10.70% to 26.38% under different treatments. Fungal-derived MNC generally contributed more to SOC (7.96–19.73%) than bacterial-derived MNC (2.62–6.65%). Soil temperature, the C/N ratio, pH, and total phosphorus influence microbial community structure and MBC, which in turn affect MNC and regulate SOC. These results enhance our understanding of how agricultural management practices on the Loess Plateau affect carbon sequestration. Full article

Wild fruit species are key components of natural and semi-natural ecosystems, playing an important role in maintaining ecological balance and supporting biodiversity. This review aims to analyze these species from the perspective of their ecological functions, contribution to biodiversity conservation, and the ecosystem services they provide. Ecologically, wild fruit species contribute to soil stabilization, nutrient cycling, and carbon sequestration, while also serving as essential food sources and habitats for a wide range of organisms, including mammals, birds, insects, and microorganisms. Through these interactions, they support ecosystem functioning and resilience. Beyond their ecological role, these species provide significant socio-economic benefits, particularly in rural areas. They contribute to cultural ecosystem services and represent valuable resources for traditional medicine, while also offering opportunities for income generation through harvesting, processing, commercialization, and rural tourism. In the context of climate change, biodiversity loss, and increasing ecosystem degradation, wild fruit species represent multifunctional natural resources. Their conservation and sustainable use are essential for maintaining ecosystem functionality and promoting sustainable rural development. Full article

Accurate prediction of soil organic carbon (SOC) in cropland is important for food production, sustainable soil management, and carbon sequestration. Although digital soil mapping (DSM) has been widely used in the prediction of SOC, most of the current DSM studies use only a single remote sensing image and a single machine learning (ML) approach, and few studies apply multi-temporal remote sensing images and ensemble methods. This study explores the accuracy of the prediction of surface SOC in cropland by comparing multi-temporal Sentinel-2A remote sensing with random forest (RF), support vector machine (SVM), gradient boosted decision trees (GBDT), extreme gradient boosted decision trees (XGBoost), and a stacking ensemble method consisting of these four ML approaches. The potential of multi-temporal remote sensing data and the stacking ensemble method for SOC prediction is discussed. To this end, 76 sampling points were selected in the study area, soil samples were collected at depths of 0–10 cm and 10–20 cm for each soil profile, and a total of 152 soil samples were obtained. Remote sensing variables extracted from topography, climate, and Sentinel-2A images on 13 January and 31 August 2023 were used as predictor variables. The results showed that the stacking ensemble method with multi-temporal predictor variables outperformed all single models and variable combinations. However, the overall predictive accuracy remained moderate, with the best performance for 0–10 cm (R² = 0.386, RMSE = 4.782, MAE = 3.36) and 10–20 cm (R² = 0.425, RMSE = 4.484, MAE = 4.031). The relatively low R² values, despite the use of advanced methods, highlight the inherent challenges of SOC prediction in highly fragmented karst croplands. This study demonstrates the incremental benefit, rather than a universal high accuracy, of combining multi-temporal Sentinel-2 imagery with a stacking ensemble to improve SOC mapping in such complex environments. Full article

Soil organic carbon (SOC) responds rapidly to vegetation changes, and exploring SOC sequestration mechanisms under different vegetation types is critical for optimizing wetland carbon sink functions. This study investigated the abiotic and biotic mechanisms driving SOC stability across four typical vegetation types (reed marsh, woodland, farmland, and wasteland) in the 0–10 cm and 10–20 cm soil layers of Hengshui Lake wetland. Results showed that reed marshes exhibited the highest total organic carbon (TOC) and particulate organic carbon (POC), owing to anaerobic soil conditions and stable macroaggregate physical protection. Woodlands accumulated higher dissolved organic carbon (DOC) and microbial biomass carbon (MBC) via an efficient microbial carbon pump, despite weaker aggregate stability. In contrast, farmlands and wastelands presented intense labile organic carbon (LOC) turnover and enzymatic decomposition, accelerating SOC mineralization and carbon dissipation with poor carbon sequestration capacity. Proteobacteria and Acidobacteriota dominated bacterial communities, while Ascomycota prevailed in fungi. Soil water content (SWC) and bulk density (BD) were the core drivers of microbial community succession, and fungi were more sensitive to vegetation changes. Conclusively, distinct vegetation types shape divergent SOC sequestration pathways. This work provides a theoretical basis for wetland restoration and regional carbon sink enhancement. Full article

Agroforestry systems are a sustainable strategy for climate change mitigation by enhancing carbon sequestration in agricultural soils, particularly in regions like Zamora Chinchipe, where they improve soil resilience and productivity in deforested landscapes. This study evaluated soil carbon storage under different land-use systems—forest, cacao monoculture, cacao-based agroforestry, and coffee-based agroforestry—as a climate change mitigation strategy. Data were collected from cacao and coffee producers regarding crop management practices on their farms. Soil samples were collected at a depth of 20 cm and analyzed for bulk density (BD), pH, soil organic matter (SOM), and carbon stocks. Land-use systems showed that coffee-based agroforestry stored 101.22 Mg ha⁻¹ of carbon and cacao-based agroforestry 71.55 Mg ha⁻¹, both exceeding values observed in cacao monoculture and even forest systems. These results suggest that cacao and coffee agroforestry systems have a greater capacity for carbon sequestration compared to monoculture systems. However, the contribution of forests should not be underestimated, as these findings are based only on the surface soil layer, which limits a comprehensive assessment of the full carbon storage potential of forest ecosystems in Zamora Chinchipe. Agroforestry systems emerge as viable and sustainable alternatives for soil carbon storage, as they integrate trees and crops, promoting long-term carbon sequestration in soils. Full article

Soil Organic Matter (SOM) and Soil Organic Carbon (SOC) are essential for regulating ecosystem functions, soil fertility, and influencing climate change processes, especially in semi-arid regions. The recent improvements in remote sensing instruments and the development of artificial intelligence methodologies, such as machine learning, enable an improved understanding of carbon dynamics, facilitate the estimation of SOC content, and support predictive modeling. This study presents an integrated framework to analyze past and future carbon dynamics in the Sfax Governorate (Tunisia). Land-use and land-cover (LULC) maps for the years 2019, 2020, 2022, and 2024 were generated using a Random Forest algorithm applied to multispectral satellite data in the Google Earth Engine platform, achieving high classification accuracy (overall accuracy up to 0.90). Carbon stocks and their temporal variations were estimated using the InVEST Carbon Storage and Sequestration model, while carbon emissions and the Net Ecosystem Carbon Balance (NECB) were derived by integrating land-use-specific emission factors. Future LULC scenarios for 2030 were simulated through a Cellular Automata model under three alternative development pathways: conservation-oriented (CONS), business-as-usual (BAU), and urban expansion (URB+). The study demonstrates how the integration of machine learning, remote sensing, and ecosystem modeling supports spatially explicit assessment of SOC-related carbon dynamics and provides useful insights for land management and climate mitigation strategies. Full article

Addressing climate change and food security, this article evaluates ground silicate rocks (remineralizers) as tools for atmospheric CO₂ capture and food and nutrition security. The experiments were conducted under controlled conditions using leaching columns, to quantify the leached carbon and pots, to evaluate the growth and nutrition of three agricultural crops. Five rock types (basalt, kamafugite, chlorite–muscovite calc–schist, hydrothermalized calc–silicate, and biotite–actinolite schist) were applied to a clayed Red Oxisol (S) at 20 t ha⁻¹, with and without organic matter (OM) at 40 t ha⁻¹. The study involved 84 experimental units, including S, S + R, S + OM, S + R + OM, and S, S + OM and NPK controls. The results demonstrate that R + OM synergies significantly improved soil chemical properties, raising pH from 5 to 7 and increasing electrical conductivity. These amendments enhanced the growth and mineral content of beans, arugula, and carrots compared to conventional NPK formulations. While OM influenced overall carbon mobility, the specific contribution of silicate minerals to carbon dioxide removal (CDR) was most evident in S + R treatments. The findings suggest that integrating regional mineral resources with organic amendments offers a scalable, sustainable alternative to synthetic fertilizers, fostering resilient agricultural systems while contributing to global carbon sequestration targets. Full article

Co-utilization of milk vetch as green manure (GM) and rice straw is an effective practice for reducing nitrogen (N) input while maintaining crop productivity in rice-based agroecosystems in southern China. The effects of soil carbon (C) and N pools and their fractions under green manuring and rice straw return, combined with reduced N fertilization remain to be clarified. A four-year field experiment was carried out to explore the effects of synergistic utilization of GM and rice straw (GMS) on rice yield, soil C and N fractions, and their contributions to rice productivity. The study demonstrated that compared with winter fallow (WF), GMS increased rice yield by 20.3% under 40% reduction in N fertilization (N60). GM application increased soil total N content by 16.5% and 18.0% significantly relative to WF under N0 and N60, respectively. GMS treatment demonstrated improvements in the soil organic C pool and enhanced soil N activity. Compared with WF, soil organic C, mineral-associated organic C and particulate organic C under GMS increased by 11.1% and 24.9%, 31.3% and 13.8%, 13.1% and 47.3% at N0 and N60 levels, respectively. Under N60, GMS increased heavy-fraction organic C content by 42.6% while reducing light-fraction organic C content by 28.0% compared to WF, thereby enhancing soil C pool stability. Regarding soil N fractions, GMS increased particulate organic N content by 60.8% and 79.3%, and mineral-associated organic N content by 89.7% and 43.4% at N0 and N60 levels, respectively. Under N60, GMS reduced heavy-fraction organic N content while increasing light-fraction organic N content, thereby enhancing soil N availability. Based on the results of Mantel tests and random forest prediction, our analysis found that N and particulate organic C served as the key factors affecting rice yield. In conclusion, GMS combined with 60% of the conventional N rate enhanced rice yield by mediating soil C sequestration and N availability, proving to be an effective strategy for improving soil fertility and ensuring food security in the rice-growing region of southern Jiangsu, China. Full article

Straw and no-tillage management, as important practices in conservation agriculture, have the potential to improve soil structure. However, their effects on the aggregate stability of soil and on active organic carbon pools in paddy fields are unclear. To investigate how different tillage and straw management practices affect soil properties, this study drew on a 15-year long-term experiment conducted in a double-cropped rice region in South China. It systematically compared four treatments: no-tillage (NT), conventional tillage (CT), conventional tillage with incorporated straw (CT-SR), and no-tillage with straw mulch (NT-SMR)—in terms of their effects on the distribution and stability of mechanical and water-stable aggregates, as well as the distribution of particulate organic carbon (POC) and mineral-associated organic carbon (MAOC) across various aggregate size fractions. The results showed that: (1) Relative to the CT, NT, and CT-SR treatments, NT-SMR significantly enhanced soil structure, as evidenced by a higher percentage of large aggregates (>0.25 mm) and improved aggregate stability. (2) NT-SMR consistently increased soil organic carbon pools, raising SOC, POC, and MAOC contents by 2.0–14.2%, 5.7–24.3%, and 1.0–11.9%, respectively, compared to other treatments. (3) In this study, stability of soil aggregates parameters (R_>0.25, MWD and GMD) increased combined with higher levels of bulk SOC and >0.053 mm MAOC, but decreased with higher fractal dimension, indicating a direct causal link between organic carbon accumulation and the betterment of soil structure. Overall, NT-SMR promotes aggregate stability through an optimized particle-size distribution and increased SOC, particularly in the >0.053 mm MAOC fraction. This practice is a sustainable long-term strategy for enhancing SOC sequestration and structural stability in paddy. Full article

Wildfires are key drivers of Mediterranean forest dynamics, yet post-fire recovery and carbon cycling in coastal dune systems remain poorly understood, particularly under invasive species pressure. This study quantified how microtopography and dominant woody species shape vegetation recovery, carbon stocks, and soil CO₂ efflux in a Pinus pinaster plantation burned in 2017 in coastal Portugal, during the fifth post-fire hydrological year (2021–2022). Vegetation composition, aboveground biomass, litter, soil organic matter and total organic carbon were measured across dune crests and slacks, and soil respiration was repeatedly assessed under native—Halimium halimifolium—and exotic invasive—Acacia longifolia—woody species using a closed-chamber system. Woody cover was higher on crests, whereas slacks supported greater herbaceous cover and stronger increases in soil organic matter, with litter dominating biomass and carbon pools in all microsites. A. longifolia showed marked demographic expansion and higher soil respiration than the native shrub, while mixed-effects models revealed non-linear, interacting effects of soil moisture and temperature on CO₂ efflux. Overall, post-fire recovery and carbon dynamics were spatially heterogeneous and increasingly controlled by invasion, underscoring the need for microsite-specific restoration and early invasive control to safeguard carbon sequestration and native forest resilience in Mediterranean coastal dunes. Full article

Understanding how land management influences soil carbon (C) and nitrogen (N) dynamics is critical for improving ecosystem resilience and carbon sequestration potential in semiarid rangelands. This study used classical field- and laboratory-based methods to assess soil organic carbon (SOC), organic matter (OM), and N content at 13 sites across four ecological provinces in eastern Oregon, USA. Treated sites—where traditional rangeland restoration and management practices had been applied to them (i.e., juniper removal, sagebrush removal, post-fire grass seeding, and land conversion to pasture)—were paired with adjacent untreated control sites. Soil samples were collected at two depths, 0 to 10 cm and 15 to 25 cm and analyzed for C, N, OM, bulk density (BD), soil volumetric water content (SVWC), porosity, and texture. Soil C and N stocks were calculated on an area basis (t ha⁻¹), and statistical analyses were conducted using one-way ANOVA and correlation tests. Treated sites generally exhibited higher soil C, N, and OM content compared to untreated sites, particularly in the upper 10 cm of soil. Data obtained from the two soil depths (0 to 10 cm and 15 to 25 cm) were averaged and assumed to represent the top 30 cm of the soil profile, corresponding to the effective rooting zone at each field. The site where sagebrush removal was followed by grass seeding exhibited the highest soil C and N stocks (115.8 t C ha⁻¹ and 9.2 t N ha⁻¹, respectively). This site also had the highest OM content (9.53%), which was observed in the topsoil layer (0 to 10 cm) across all sites and depths. Strong positive correlations between C and N were detected across all sites (mean r = 0.92), while negative correlations were observed between soil C and bulk density at several locations. Results suggest that vegetation management practices such as woody plant removal and grass establishment can enhance soil C storage and nutrient retention in semiarid rangeland ecosystems. These findings provide baseline data to inform land management strategies aimed at improving soil health and carbon sequestration potential in the Pacific Northwest region in the USA. Full article

Agricultural soils play a dual role in the climate system, acting both as carbon sinks and natural sources of greenhouse gas emissions, which may be intensified under unsustainable management. However, the comparative effectiveness of different soil management strategies, particularly organic amendments derived from agro-industrial residues, remains insufficiently clarified. This review aims to critically synthesize current scientific evidence on soil stewardship practices for mitigating greenhouse gas emissions and enhancing soil carbon sequestration. The analysis is based on a structured review of peer-reviewed literature published over the last decade, including field experiments, long-term trials, and LCA studies. Comparative insights are provided across conventional mineral fertilization, organic amendments, and circular fertilization approaches based on agro-industrial by-products. The results indicate that organic amendments such as compost, digestate, and vermicompost generally increase soil organic carbon stocks (up to +40% in long-term systems) and can reduce greenhouse gas emissions and carbon footprint compared with mineral fertilization, although responses vary depending on soil, climate, and management conditions. The review evaluates the effects of different management practices on soil organic carbon dynamics, greenhouse gas fluxes, nutrient use efficiency, and soil biological functioning. Special emphasis is placed on the role of waste-derived fertilizers—such as composts, digestates, and vermicompost—in promoting soil carbon stabilization while reducing the environmental burden associated with synthetic inputs. Evidence consistently indicates that soil stewardship strategies grounded in circular economy principles can lower net carbon footprints, improve soil resilience, and mitigate trade-offs between productivity and climate mitigation. By framing soil management within the context of global warming mitigation, this review highlights the multifunctional role of soils as climate regulators and underscores the potential of agro-industrial waste valorization as a scalable pathway toward climate-smart and low-emission agricultural systems. Full article

Microplastics (MPs) are increasingly recognized as persistent, carbon-based contaminants in biosolids produced during wastewater treatment. As biosolids are widely applied to land or disposed of via landfilling and incineration, the incorporation of microplastic-derived carbon into managed and natural ecosystems raises important questions regarding carbon cycling, organic carbon stability, and long-term environmental implications. This review synthesizes current knowledge on the occurrence, characteristics, and fate of microplastics in biosolids, with particular emphasis on their interactions with native organic matter and their influence on carbon-related processes. This work critically assesses how MPs in biosolids influence carbon dynamics, including their role as a persistent carbon pool, interactions with soil organic matter, effects on microbial activity and decomposition, and implications for carbon sequestration and turnover after land application. The review also considers indirect consequences for food systems and human exposure through carbon-associated pathways. Significant knowledge gaps remain regarding the quantification of microplastic-associated carbon stocks and fluxes, transformation processes during biosolid treatment and soil incorporation, and the long-term persistence of this carbon fraction. Methodological challenges in measuring and reporting MPC are briefly highlighted, alongside their implications for understanding MPs as an emerging component of the terrestrial carbon cycle and for sustainable biosolid management. Full article

Litter decomposition plays a critical role in the formation and turnover of soil organic carbon (SOC) and its fractions. However, the effects of litter on SOC dynamics across grassland degradation remain poorly understood. The objectives of this study were to investigate the responses of SOC and its fractions, including particulate organic carbon (POC) and mineral-associated organic carbon (MAOC), to litter decomposition in lightly, moderately, and highly degraded grasslands. A 240-day incubation experiment using Leymus chinensis litter incubated on day 0, 23, 60, and 240 was conducted to investigate the biotic and abiotic factors regulating SOC stability. Grassland degradation significantly reduced POC and MAOC concentrations; moreover, litter addition in degraded grasslands further reduced SOC. In the lightly and moderately degraded grasslands, litter addition modulated POC and MAOC via both microbial and physicochemical pathways. In the highly degraded grasslands, litter addition influenced POC and MAOC not only indirectly through microbial and physicochemical pathways but also directly by promoting MAOC formation. Overall, although litter decomposition altered SOC and its fractions, its effects were constrained by the degree of grassland degradation. These findings indicate that restoration strategies should prioritize enhancing microbial biomass and activity in lightly and moderately degraded grasslands while increasing litter inputs in highly degraded grasslands to improve soil carbon sequestration. Full article