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20 pages, 4695 KB  
Article
Influence of Composite Amendments on the Characteristics of Sandy Soil
by Xinrui Sui, Lingyan Wang, Xinyao Lv, Yanan Liu, Yuqi Zhu, Lingyun Fan and Hanxi Wang
Sustainability 2025, 17(17), 7619; https://doi.org/10.3390/su17177619 - 23 Aug 2025
Viewed by 436
Abstract
Soil desertification control is a global challenge, and the barrenness of sandy soil limits the growth of plants. To enhance the vegetation growth capacity of sandy soils, the preparation of soil amendments and the experiment of improving desertified soil were conducted. The soil [...] Read more.
Soil desertification control is a global challenge, and the barrenness of sandy soil limits the growth of plants. To enhance the vegetation growth capacity of sandy soils, the preparation of soil amendments and the experiment of improving desertified soil were conducted. The soil amendment is prepared by mixing polyacrylamide (2.7%), biochar (16.2%), sodium bentonite (16.2%), straw fibers (5.4%), corn straw (2.7%), sheep manure organic fertilizer (54.1%), and composite microbial agents (2.7%). The laboratory experiment was conducted to investigate the effects of varying rates (0, 1.5%, 3%, 4.5%, 6%) of composite soil amendments on the properties of sandy soil and the Lolium perenne L. with a growth period of 30–60 days. The results indicated that the application of composite amendments at different rates maintained the soil pH between 7.0 and 7.5, increased the electrical conductivity, and significantly improved the soil moisture content, soil organic carbon (SOC), total nitrogen (TN), and total phosphorus contents. Under the condition of 3% amendment, the soil TN content increased from 0.74 to 1.83 g·kg−1. The composite amendments remarkably promoted L. perenne growth, as evidenced by increased plant height, dry weight, and nitrogen and phosphorus nutrient content, while the SOC content increased by 1–4 times. The application of composite amendments, prepared by mixing materials such as biochar, organic fertilizer, crop straw, microbial agents, bentonite, and water-retaining agents, enhanced the physicochemical properties of sandy soil and promoted L. perenne growth, and 3% was the most suitable application rate. These findings are expected to advance desertification-controlling technologies and enhance soil carbon sequestration capacity. Full article
(This article belongs to the Section Soil Conservation and Sustainability)
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23 pages, 4172 KB  
Article
Predicting Soil Organic Carbon from Sentinel-2 Imagery and Regional Calibration Approach in Salt-Affected Agricultural Lands: Feasibility and Influence of Soil Properties
by Mohammad Farzamian, Nádia Castanheira, Maria C. Gonçalves, Pedro Freitas, Mohammadmehdi Saberioon, Tiago B. Ramos, João Antunes and Ana Marta Paz
Remote Sens. 2025, 17(16), 2877; https://doi.org/10.3390/rs17162877 - 18 Aug 2025
Viewed by 483
Abstract
Mapping Soil Organic Carbon (SOC) at a regional scale is essential for assessing soil health and supporting sustainable land management. This study evaluates the potential of using Sentinel-2 imagery and regional calibration to predict SOC in salt-affected agricultural lands in Portugal while also [...] Read more.
Mapping Soil Organic Carbon (SOC) at a regional scale is essential for assessing soil health and supporting sustainable land management. This study evaluates the potential of using Sentinel-2 imagery and regional calibration to predict SOC in salt-affected agricultural lands in Portugal while also assessing the influence of soil properties, such as texture and salinity, on SOC prediction. A per-pixel mosaicking approach was set to analyze the relationship of spectral reflectance indices linked to bare soil conditions with SOC. SOC prediction models were developed using linear regression (LR) and Partial Least Squares Regression (PLSR). Among the tested approaches, the combination of the maximum Bare Soil Index (maxBSI) with LR produced the most accurate SOC predictions, achieving moderate prediction performance (R2 = 0.52; RMSE = 0.16%; LCCC = 70%). This approach slightly outperformed the application of the 90th percentile of bare soil pixels (R90 reflectance) and the median approaches with PLSR. Notably, our findings indicate that soil salinity did not significantly affect SOC predictions within the observed salinity range of ECe between 1.2 and 10.4 dS m−1 in topsoil. However, further case studies are needed to validate this observation across diverse agricultural conditions. In contrast, soil texture and moisture content emerged as the dominant factors influencing soil reflectance. The combination of per-pixel mosaicking and regional calibration provides a practical, scalable, and cost-effective method for generating SOC maps using open access satellite imagery. To support wider adoption and improve model generalizability, future studies should incorporate a larger number of fields with a wider range of soil properties, crop types, and management practices. Full article
(This article belongs to the Collection Sentinel-2: Science and Applications)
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26 pages, 24560 KB  
Article
The Assessment of Ecosystem Stability and Analysis of Influencing Factors in Arid Desert Regions from 2000 to 2020: A Case Study of the Alxa Desert in China
by Boyang Wang, Jianhua Si, Bing Jia, Dongmeng Zhou, Zijin Liu, Boniface Ndayambaza, Xue Bai, Yang Yang and Lina Yi
Remote Sens. 2025, 17(16), 2871; https://doi.org/10.3390/rs17162871 - 18 Aug 2025
Viewed by 396
Abstract
Accurately assessing the spatiotemporal dynamics and influencing factors of ecosystem stability in arid desert regions (ADR) is crucial for ecological conservation and the achievement of high-quality regional development. However, existing assessment frameworks generally fail to adapt to the extremely fragile ecological conditions of [...] Read more.
Accurately assessing the spatiotemporal dynamics and influencing factors of ecosystem stability in arid desert regions (ADR) is crucial for ecological conservation and the achievement of high-quality regional development. However, existing assessment frameworks generally fail to adapt to the extremely fragile ecological conditions of ADR. Therefore, the Alxa Desert, a typical region, was selected as the research region, and an ecosystem stability assessment framework tailored to regional characteristics (perturbation–resilience–function) was constructed. Perturbation represents external pressure, resilience reflects the capacity for recovery and adaptation, and function serves as the supporting foundation. The three dimensions are dynamically coupled and jointly determine the stability status of the ecosystem in the Alxa Desert. Methodologically, this study innovatively introduces the Cloud Model–Analytic Hierarchy Process (CM-AHP) to calculate indicator weights, which more effectively addressed the widespread fuzziness and uncertainty inherent in ecosystem assessments compared to traditional methods. In addition, spatial autocorrelation methods was applied to reveal the spatial and temporal evolution characteristics of ecosystem stability from 2000 to 2020. Furthermore, the optimal parameters geographical detector model (OPGDM) was applied to analyze the effects of natural and human factors on the spatial differentiation of ecosystem stability in Alxa Desert. In addition, the Markov–FLUS model was employed to simulate the future trends of ecosystem stability over the next two decades. The results indicate that ecosystem stability in Alxa Desert from 2000 to 2020 was primarily characterized by vulnerable and moderate levels, with the area classified as extremely vulnerable decreasing significantly by 10% relative to its extent in 2000. Spatially, higher stability was observed in oasis regions and southeastern mountainous regions, while lower stability was concentrated in the desert hinterlands. Overall, ecosystem stability shifted from vulnerable toward moderate levels, reflecting a trend of gradual improvement. From 2000 to 2020, the Moran’s I varied between 0.78 and 0.81, showing strong spatial clustering. Surfce Soil moisture content (SSMC), Soil organic carbon (SOC), and enhanced vegetation index (EVI) were the primary factors influencing the spatial differentiation of ecosystem stability in Alxa Desert. The interaction between these factors further enhanced their explanatory power. Future forecasting results indicate that ecosystem stability will further improve by 2030 and 2040, particularly in the northern and southern areas of Alxa Left Banner and Alxa Right Banner. The findings can offer a theoretical foundation for future ecological conservation and environmental management in ADR. Full article
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28 pages, 2543 KB  
Article
Chemical Fractions of Soil Organic Matter and Their Interactions with Cu, Zn, and Mn in Vineyards in Southern Brazil
by Guilherme Wilbert Ferreira, Samya Uchoa Bordallo, Lucas Dupont Giumbelli, Zayne Valéria Santos Duarte, Gustavo Brunetto, George Wellington Bastos de Melo, Deborah Pinheiro Dick, Tadeu Luis Tiecher, Tales Tiecher and Cledimar Rogério Lourenzi
Agronomy 2025, 15(8), 1937; https://doi.org/10.3390/agronomy15081937 - 12 Aug 2025
Viewed by 367
Abstract
This study aimed to evaluate the impact of vineyard cultivation time and the use of metal-based fungicides on the chemical fractions of soil organic matter (SOM) as well as their interactions with Cu, Zn, and Mn in vineyard soils from Southern Brazil with [...] Read more.
This study aimed to evaluate the impact of vineyard cultivation time and the use of metal-based fungicides on the chemical fractions of soil organic matter (SOM) as well as their interactions with Cu, Zn, and Mn in vineyard soils from Southern Brazil with varying histories of fungicide application. Soil samples were collected in 2017 from vineyards aged 35, 37, and 39 years in the Serra Gaúcha region and 13, 19, and 36 years in the Campanha Gaúcha. In each region, samples were also collected from a non-anthropized reference area. In the oldest vineyards, sampling was conducted both within and between the rows of planting. Chemical fractionation of SOM was performed: non-humic substances (nHSs), particulate organic matter (POM), fulvic acid (FA), humic acid (HA), and humin (Hu). Fourier-transform infrared (FTIR) spectra were obtained for the HA, from which the aromaticity index (AI) and relative intensities (RIs) were calculated. In each SOM fraction, total organic carbon and the concentrations of Cu, Zn, and Mn were determined. Changes in land use alter the forms and distribution of soil organic carbon (SOC) and, consequently, of metals. Elemental and spectroscopic analyses of HS revealed that HA in the reference areas (forest and native grassland) was more aliphatic and had higher concentrations of polysaccharides, indicating fractions with a lower degree of stabilization. However, in vineyard areas, HA exhibited greater humification and aromaticity. Increasing cultivation time gradually increased soil carbon content, indicating that viticultural agroecosystems can sequester carbon in the soil over time, reaching levels similar to those observed in the reference areas. When comparing vineyard areas alone, with row collections and inter-row collections, we observed an increase in SOC levels in areas managed with cover crops, demonstrating the importance of conservation management in these areas. When evaluating the distribution of metals in these soils, we could observe the high affinity of Cu for the functional groups of SOM, with FA and HA responsible for the complexation of these elements in the soil. For Zn and Mn, the greatest accumulations were observed in the Hu fraction due to their greater affinity for soil clay minerals. This shows that soil organic matter is a key component in the complexation of metals in soils, reducing their availability and potential toxicity to cultivated plants. Full article
(This article belongs to the Special Issue Soil Organic Matter and Tillage)
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20 pages, 1687 KB  
Article
Partial Organic Substitution Improves Soil Quality and Increases Latex Yield in Rubber Plantations
by Wenxian Xu, Wenjie Liu, Congju Zhao, Yingying Zhang, Ashar Tahir, Xinwei Guo, Rui Sun, Qiu Yang and Zhixiang Wu
Agronomy 2025, 15(8), 1936; https://doi.org/10.3390/agronomy15081936 - 12 Aug 2025
Viewed by 408
Abstract
Partial organic substitution (POS) is a promising strategy to enhance soil fertility and agricultural sustainability. However, the mechanisms by which varying organic substitution ratios affect soil quality and latex yields in rubber plantations remain unclear. We conducted a two-year field experiment in a [...] Read more.
Partial organic substitution (POS) is a promising strategy to enhance soil fertility and agricultural sustainability. However, the mechanisms by which varying organic substitution ratios affect soil quality and latex yields in rubber plantations remain unclear. We conducted a two-year field experiment in a rubber plantation with six treatments: no fertilizer (CK), 100% synthetic fertilizer (NPK), and synthetic nitrogen fertilizer substituted with 25% (25 M), 50% (50 M), 75% (75 M), and 100% (100 M) manure. The results indicated that POS treatments significantly increased pH, soil organic carbon (SOC), total phosphorus (TP), total nitrogen (TN), NH4+-N, enzyme activity, and leaf nutrient (C, N, and P) content compared to NPK. Compared with NPK, the soil quality (evaluated through the soil quality index, SQI) increased by 15.30–43.42% under POS across both years, with maximal values observed at 50 M (2020) and 75 M (2021); similarly, the latex yield increased by 2.10–18.60%. SOC, NO3-N,C:P ratio, TN, and pH are the key factors that influence soil quality and latex yield. Structural equation modeling indicated that fertilization and soil factors collectively explained 82% of the variation in latex yield. These results demonstrated that POS effectively alleviated soil acidity, enhanced soil quality, and improved latex productivity, with 50% manure substitution treatment (50M) identified as the optimal short-term substitution strategy in rubber plantations. Full article
(This article belongs to the Section Innovative Cropping Systems)
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20 pages, 4835 KB  
Article
Soil Inorganic Carbon Content and Its Environmental Controls in the Weibei Loess Region: A Random Forest-Based Spatial Analysis
by Duoxun Xu, Yongkang Ding, Yuchen Yan, Jianli Qian, Qianzhuo Zhao and Anquan Xia
Land 2025, 14(8), 1609; https://doi.org/10.3390/land14081609 - 8 Aug 2025
Viewed by 406
Abstract
Soil carbon constitutes the largest terrestrial carbon reservoir, with inorganic forms (SIC) contributing an estimated 20–40% of the global total. Despite its relevance to arid-region carbon cycling and stabilization, SIC remains less studied than soil organic carbon (SOC). This study quantified surface SIC [...] Read more.
Soil carbon constitutes the largest terrestrial carbon reservoir, with inorganic forms (SIC) contributing an estimated 20–40% of the global total. Despite its relevance to arid-region carbon cycling and stabilization, SIC remains less studied than soil organic carbon (SOC). This study quantified surface SIC content (0–20 cm) and its environmental drivers across the Weibei Loess region using 3261 soil samples collected between 2008 and 2010. A combination of Random Forest (RF) modeling and optimal parameter geodetector (OPGD) analysis was employed to assess spatial heterogeneity and identify key environmental controls. SIC content ranged from 0.10 to 3.56 g kg−1 (mean = 1.23 ± 0.41 g kg−1), generally lower than reported values in the Tibetan Plateau and Inner Mongolia. Higher concentrations were observed in central areas, with lower values toward the periphery. While mean annual temperature (MAT) and precipitation (MAP) remained key climatic correlates, shortwave radiation (srad) emerged as the strongest control on SIC across the region, exhibiting a significant positive association with its accumulation. Notably, its interaction with wind speed (vs) further amplified this effect, highlighting the synergistic role of radiation and near-surface turbulence in regulating inorganic carbon retention in surface soils. Collectively, these variables explained ~56% of SIC spatial variation. Favorable conditions for SIC accumulation were identified within specific environmental thresholds: srad (171–172 W/m2), MAP (546–587 mm), MAT (10.2–11.5 °C), and vs (1.90–1.96 m/s). These findings offer a quantitative basis for understanding SIC patterns in loess-derived soils and support the development of region-specific strategies for carbon regulation under changing climatic conditions. Full article
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17 pages, 3193 KB  
Article
Effects of Nitrogen and Phosphorus Additions on the Stability of Soil Carbon Fractions in Subtropical Castanopsis sclerophylla Forests
by Yunze Dai, Xiaoniu Xu and LeVan Cuong
Forests 2025, 16(8), 1264; https://doi.org/10.3390/f16081264 - 2 Aug 2025
Viewed by 311
Abstract
Soil organic carbon (SOC) pool plays an extremely important role in regulating the global carbon (C) cycle and climate change. Atmospheric nitrogen (N) and phosphorus (P) deposition caused by human activities has significant impacts on soil C sequestration potential of terrestrial ecosystem. To [...] Read more.
Soil organic carbon (SOC) pool plays an extremely important role in regulating the global carbon (C) cycle and climate change. Atmospheric nitrogen (N) and phosphorus (P) deposition caused by human activities has significant impacts on soil C sequestration potential of terrestrial ecosystem. To investigate the effects of N and P deposition on soil C sequestration and C-N coupling relationship in broad-leaved evergreen forests, a 6-year field nutrient regulation experiment was implemented in subtropical Castanopsis sclerophylla forests with four different N and P additions: N addition (100 kg N·hm−2·year−1), N + P (100 kg N·hm−2·year−1 + 50 kg P·hm−2·year−1), P addition (50 kg P·hm−2·year−1), and CK (0 kg N·hm−2·year−1). The changes in the C and N contents and stable isotope distributions (δ13C and δ15N) of different soil organic fractions were examined. The results showed that the SOC and total nitrogen (STN) (p > 0.05) increased with N addition, while SOC significantly decreased with P addition (p < 0.05), and N + P treatment has low effect on SOC, STN (p > 0.05). By density grouping, it was found that N addition significantly increased light fraction C and N (LFOC, LFN), significantly decreased the light fraction C to N ratio (LFOC/N) (p < 0.05), and increased heavy fraction C and N (HFOC, HFN) accumulation and light fraction to total organic C ratio (LFOC/SOC, p > 0.05). Contrary to N addition, P addition was detrimental to the accumulation of LFOC, LFN and reduced LFOC/SOC. It was found that different reactive oxidized carbon (ROC) increased under N addition but ROC/SOC did not change, while N + P and P treatments increased ROC/SOC, resulting in a decrease in SOC chemical stability. Stable isotope analysis showed that N addition promoted the accumulation of new soil organic matter, whereas P addition enhanced the transformation and utilization of C and N from pre-existing organic matter. Additionally, N addition indirectly increased LFOC by significantly decreasing pH; significantly contributed to LFOC and ROC by increasing STN accumulation promoted by NO3-N and NH4+-N; and decreased light fraction δ13C by significantly increasing dissolved organic C (p < 0.05). P addition had directly significant negative effect on LFOC and SOC (p < 0.05). In conclusion, six-year N deposition enhances soil C and N sequestration while the P enrichment reduces the content of soil C, N fractions and stability in Castanopsis sclerophylla forests. The results provide a scientific basis for predicting the soil C sink function of evergreen broad-leaved forest ecosystem under the background of future climate change. Full article
(This article belongs to the Section Forest Soil)
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17 pages, 5265 KB  
Article
Influence of Agricultural Practices on Soil Physicochemical Properties and Rhizosphere Microbial Communities in Apple Orchards in Xinjiang, China
by Guangxin Zhang, Zili Wang, Huanhuan Zhang, Xujiao Li, Kun Liu, Kun Yu, Zhong Zheng and Fengyun Zhao
Horticulturae 2025, 11(8), 891; https://doi.org/10.3390/horticulturae11080891 - 1 Aug 2025
Viewed by 348
Abstract
In response to the challenges posed by soil degradation in the arid regions of Xinjiang, China, green and organic management practices have emerged as effective alternatives to conventional agricultural management methods, helping to mitigate soil degradation by promoting natural soil recovery and ecological [...] Read more.
In response to the challenges posed by soil degradation in the arid regions of Xinjiang, China, green and organic management practices have emerged as effective alternatives to conventional agricultural management methods, helping to mitigate soil degradation by promoting natural soil recovery and ecological balance. However, most of the existing studies focus on a single management practice or indicator and lack a systematic assessment of the effects of integrated orchard management in arid zones. This study aims to investigate how different agricultural management practices influence soil physicochemical properties and inter-root microbial communities in apple orchards in Xinjiang and to identify the main physicochemical factors affecting the composition of inter-root microbial communities. Inter-root soil samples were collected from apple orchards under green management (GM), organic management (OM), and conventional management (CM) in major apple-producing regions of Xinjiang. Microbial diversity and community composition of the samples were analyzed using high-throughput amplicon sequencing. The results revealed significant differences (p < 0.05) in soil physicochemical properties across different management practices. Specifically, GM significantly reduced soil pH and C:N compared with OM. Both OM and GM significantly decreased soil available nutrient content compared with CM. Moreover, GM and OM significantly increased bacterial diversity and changed the community composition of bacteria and fungi. Proteobacteria and Ascomycota were identified as the dominant bacteria and fungi, respectively, in all management practices. Linear discriminant analysis (LEfSe) showed that biomarkers were more abundant under OM, suggesting that OM may contribute to ecological functions through specific microbial taxa. Co-occurrence network analysis (building a network of microbial interactions) demonstrated that the topologies of bacteria and fungi varied across different management practices and that OM increased the complexity of microbial co-occurrence networks. Mantel test analysis (analyzing soil factors and microbial community correlations) showed that C:N and available potassium (AK) were significantly and positively correlated with the community composition of bacteria and fungi, and that C:N, soil organic carbon (SOC), and alkaline hydrolyzable nitrogen (AN) were significantly and positively correlated with the diversity of fungi. Redundancy analysis (RDA) further indicated that SOC, C:N, and AK were the primary soil physicochemical factors influencing the composition of microbial communities. This study provides theoretical guidance for the sustainable management of orchards in arid zones. Full article
(This article belongs to the Section Fruit Production Systems)
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16 pages, 3753 KB  
Article
Elevational Patterns and Seasonal Dynamics of Soil Organic Carbon Fractions and Content in Rice Paddies of Yuanyang Terrace, Southwest China
by Haitao Li, Linxi Chang, Yonglin Wu, Yang Li, Xinran Liang, Fangdong Zhan and Yongmei He
Agronomy 2025, 15(8), 1868; https://doi.org/10.3390/agronomy15081868 - 1 Aug 2025
Viewed by 335
Abstract
Soil organic carbon (SOC) is an important part of the global C pool and is sensitive to climate change. The SOC content and fractions of rice paddies along four elevations (250, 1150, 1600 and 1800 m) on the same slope in four seasons [...] Read more.
Soil organic carbon (SOC) is an important part of the global C pool and is sensitive to climate change. The SOC content and fractions of rice paddies along four elevations (250, 1150, 1600 and 1800 m) on the same slope in four seasons (spring, summer, autumn and winter) at Yuanyang Terrace in southwest China were investigated, and their relationship with environmental factors was analyzed. The contents of SOC, unprotected SOC (uPOM), physically protected SOC (pPOM) and biochemically protected SOC (bcPOM) in rice paddies at a low elevation (250 m), were significantly lower by 49–51% than those at relatively high elevations (1600 m and 1800 m). Among the SOC fractions, the highest proportion (33–50%) was uPOM, followed by pPOM and bcPOM (accounting for 17–40%), and the lowest proportion was chemically protected SOC (cPOM). In addition, there were interseasonal differences among the contents of SOC fractions, with a significantly higher content of SOC, uPOM and pPOM at an elevation of 1600 m in summer than in the other three seasons, whereas the cPOM content at an elevation of 250 m in spring was significantly higher than in the other three higher elevations. According to the redundancy analysis (RDA), total nitrogen was the key environmental factor, with an explanatory degree of 56% affecting the contents of SOC and its fractions. Thus, the SOC content increased with increasing elevation, and physical and biochemical protection were potential stabilization mechanisms responsible for their stability in the rice paddy of Yuanyang Terrace. These results provides empirical evidence for the elevational distribution patterns and seasonal dynamics of SOC fractions in rice paddies across Yuanyang Terrace. These findings highlight the importance of physical and biochemical protection mechanisms in stabilizing SOC in rice paddies, which could enhance long-term C sequestration and contribute to climate change mitigation in terraced agroecosystems. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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19 pages, 2089 KB  
Article
Estimation of Soil Organic Carbon Content of Grassland in West Songnen Plain Using Machine Learning Algorithms and Sentinel-1/2 Data
by Haoming Li, Jingyao Xia, Yadi Yang, Yansu Bo and Xiaoyan Li
Agriculture 2025, 15(15), 1640; https://doi.org/10.3390/agriculture15151640 - 29 Jul 2025
Viewed by 239
Abstract
Based on multi-source data, including synthetic aperture radar (Sentinel-1, S1) and optical satellite images (Sentinel-2, S2), topographic data, and climate data, this study explored the performance and feasibility of different variable combinations in predicting SOC using three machine learning models. We designed the [...] Read more.
Based on multi-source data, including synthetic aperture radar (Sentinel-1, S1) and optical satellite images (Sentinel-2, S2), topographic data, and climate data, this study explored the performance and feasibility of different variable combinations in predicting SOC using three machine learning models. We designed the three models based on 244 samples from the study area, using 70% of the samples for the training set and 30% for the testing set. Nine experiments were conducted under three variable scenarios to select the optimal model. We used this optimal model to achieve high-precision predictions of SOC content. Our results indicated that both S1 and S2 data are significant for SOC prediction, and the use of multi-sensor data yielded more accurate results than single-sensor data. The RF model based on the integration of S1, S2, topography, and climate data achieved the highest prediction accuracy. In terms of variable importance, the S2 data exhibited the highest contribution to SOC prediction (31.03%). The SOC contents within the study region varied between 4.16 g/kg and 29.19 g/kg, showing a clear spatial trend of higher concentrations in the east than in the west. Overall, the proposed model showed strong performance in estimating grassland SOC and offered valuable scientific guidance for grassland conservation in the western Songnen Plain. Full article
(This article belongs to the Section Artificial Intelligence and Digital Agriculture)
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17 pages, 1397 KB  
Article
Comparison of Soil Organic Carbon Measurement Methods
by Wing K. P. Ng, Pete J. Maxfield, Adrian P. Crew, Dayane L. Teixeira, Tim Bevan and Matt J. Bell
Agronomy 2025, 15(8), 1826; https://doi.org/10.3390/agronomy15081826 - 28 Jul 2025
Viewed by 474
Abstract
To enhance agricultural soil health and soil organic carbon (SOC) sequestration, it is important to accurately measure SOC. The aim of this study was to compare common methods for measuring SOC in soils in order to determine the most effective approach among different [...] Read more.
To enhance agricultural soil health and soil organic carbon (SOC) sequestration, it is important to accurately measure SOC. The aim of this study was to compare common methods for measuring SOC in soils in order to determine the most effective approach among different agricultural land types. The measurement methods of loss-on-ignition (LOI), automated dry combustion (Dumas), and real-time near-infrared spectroscopy (NIRS) were compared. A total of 95 soil core samples, ranging in clay and calcareous content, were collected across a range of agricultural land types from forty-eight fields across five farms in the Southwest of England. There were similar and positive correlations between all three methods for measuring SOC (ranging from r = 0.549 to 0.579; all p < 0.001). On average, permanent grass fields had higher SOC content (6.6%) than arable and temporary ley fields (4.6% and 4.5%, respectively), with the difference of 2% indicating a higher carbon storage potential in permanent grassland fields. Newly predicted conversion equations of linear regression were developed among the three measurement methods according to all the fields and land types. The correlation of the conversation equations among the three methods in permanent grass fields was strong and significant compared to those in both arable and temporary ley fields. The analysed results could help understand soil carbon management and maximise sequestration. Moreover, the approach of using real-time NIRS analysis with a rechargeable portable NIRS soil device can offer a convenient and cost-saving alternative for monitoring preliminary SOC changes timely on or offsite without personnel risks from the high-temperature furnace and chemical reagent adopted in the LOI and Dumas processes, respectively, at the laboratory. Therefore, the study suggests that faster, lower-cost, and safer methods like NIRS for analysing initial SOC measurements are now available to provide similar SOC results as traditional soil analysis methods of the LOI and Dumas. Further studies on assessing SOC levels in different farm locations, land, and soil types across seasons using NIRS will improve benchmarked SOC data for farm stakeholders in making evidence-informed agricultural practices. Full article
(This article belongs to the Section Soil and Plant Nutrition)
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21 pages, 2263 KB  
Article
Elevational Patterns and Drivers of Soil Total, Microbial, and Enzymatic C:N:P Stoichiometry in Karst Peak-Cluster Depressions in Southwestern China
by Siyu Chen, Chaohao Xu, Cong Hu, Chaofang Zhong, Zhonghua Zhang and Gang Hu
Forests 2025, 16(8), 1216; https://doi.org/10.3390/f16081216 - 24 Jul 2025
Viewed by 371
Abstract
Elevational gradients in temperature, moisture, and vegetation strongly influence soil nutrient content and stoichiometry in mountainous regions. However, exactly how total, microbial, and enzymatic carbon (C), nitrogen (N), and phosphorus (P) stoichiometry vary with elevation in karst peak-cluster depressions remains poorly understood. To [...] Read more.
Elevational gradients in temperature, moisture, and vegetation strongly influence soil nutrient content and stoichiometry in mountainous regions. However, exactly how total, microbial, and enzymatic carbon (C), nitrogen (N), and phosphorus (P) stoichiometry vary with elevation in karst peak-cluster depressions remains poorly understood. To address this, we studied soil total, microbial, and enzymatic C:N:P stoichiometry in seasonal rainforests within karst peak-cluster depressions in southwestern China at different elevations (200, 300, 400, and 500 m asl) and depths (0–20 and 20–40 cm). We found that soil organic carbon (SOC), total nitrogen (TN), and the C:P and N:P ratios increased significantly with elevation, whereas total phosphorus (TP) decreased. Microbial phosphorus (MBP) also declined with elevation, while the microbial N:P ratio rose. Activities of nitrogen- (β-N-acetylglucosaminidase and L-leucine aminopeptidase combined) and phosphorus-related enzymes (alkaline phosphatase) increased markedly with elevation, suggesting potential phosphorus limitation for plant growth at higher elevations. Our results suggest that total, microbial, and enzymatic soil stoichiometry are collectively shaped by topography and soil physicochemical properties, with elevation, pH, and exchangeable calcium (ECa) acting as the key drivers. Microbial stoichiometry exhibited positive interactions with soil stoichiometry, while enzymatic stoichiometry did not fully conform to the expectations of resource allocation theory, likely due to the functional specificity of phosphatase. Overall, these findings enhance our understanding of C–N–P biogeochemical coupling in karst ecosystems, highlight potential nutrient limitations, and provide a scientific basis for sustainable forest management in tropical karst regions. Full article
(This article belongs to the Section Forest Soil)
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19 pages, 2388 KB  
Article
Impact of Grassland Management System Intensity on Composition of Functional Groups and Soil Chemical Properties in Semi-Natural Grasslands
by Urška Lisec, Maja Prevolnik Povše, Miran Podvršnik and Branko Kramberger
Plants 2025, 14(15), 2274; https://doi.org/10.3390/plants14152274 - 24 Jul 2025
Viewed by 395
Abstract
Semi-natural grasslands are some of the most species-rich habitats in Europe and provide important ecosystem services such as biodiversity conservation, carbon sequestration and soil fertility maintenance. This study investigates how different intensities of grassland management affect the composition of functional groups and soil [...] Read more.
Semi-natural grasslands are some of the most species-rich habitats in Europe and provide important ecosystem services such as biodiversity conservation, carbon sequestration and soil fertility maintenance. This study investigates how different intensities of grassland management affect the composition of functional groups and soil chemical properties. Five grassland management systems were analyzed: Cut3—three cuts per year; LGI—low grazing intensity; CG—combined cutting and grazing; Cut4—four cuts per year; and HGI—high grazing intensity. The functional groups assessed were grasses, legumes and forbs, while soil samples from three depths (0–10, 10–20 and 20–30 cm) were analyzed for their chemical properties (soil organic carbon—SOC; soil total nitrogen—STN; inorganic soil carbon—SIC; soil organic matter—SOM; potassium oxide—K2O; phosphorus pentoxide—P2O5; C/N ratio; and pH) and physical properties (volumetric soil water content—VWC; bulk density—BD; and porosity—POR). The results showed that less intensive systems had a higher proportion of legumes, while species diversity, as measured via the Shannon index, was the highest in the Cut4 system. The CG system tended to have the highest SOC and STN at a 0–10 cm depth, with a similar trend observed for SOCstock at a 0–30 cm depth. The Cut4, HGI and CG systems also had an increased STNstock. Both grazing systems had the highest P2O5 content. A tendency towards a higher BD was observed in the top 10 cm of soil in the more intensive systems. Choosing a management strategy that is tailored to local climate and site conditions is crucial for maintaining grassland stability, enhancing carbon sequestration and promoting long-term sustainability in the context of climate change. Full article
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21 pages, 4580 KB  
Article
Response of Patch Characteristics of Carex alatauensis S. R. Zhang to Establishment Age in Artificial Grasslands on the Qinghai–Tibet Plateau, China
by Liangyu Lyu, Chao Wang, Pei Gao, Fayi Li, Qingqing Liu and Jianjun Shi
Plants 2025, 14(15), 2257; https://doi.org/10.3390/plants14152257 - 22 Jul 2025
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Abstract
To clarify the ecological mechanisms underlying the succession of artificial grasslands to native alpine meadows and systematically reveal the patterns of ecological restoration in artificial grasslands in the Qinghai–Tibet Plateau, this study provides a theoretical basis for alpine meadow ecological restoration. In this [...] Read more.
To clarify the ecological mechanisms underlying the succession of artificial grasslands to native alpine meadows and systematically reveal the patterns of ecological restoration in artificial grasslands in the Qinghai–Tibet Plateau, this study provides a theoretical basis for alpine meadow ecological restoration. In this study, artificial grassland and degraded grassland (CK) with different restoration years (20 years, 16 years, 14 years, and 2 years) in the Qinghai–Tibet Plateau were taken as research objects. We focused on the tillering characteristics, patch number, community structure evolution, and soil properties of the dominant species, C. alatauensis, and systematically explored the ecological restoration law by comparing and analyzing ecological indicators in different restoration years. The results showed the following: (1) With the extension of restoration years, the asexual reproduction ability of C. alatauensis was enhanced, the patches became large, and aboveground/underground biomass significantly accumulated. (2) Community structure optimization meant that the coverage and biomass of Cyperaceae plants increased with restoration age, while those of Poaceae plants decreased. The diversity of four species in 20A of restored grasslands showed significant increases (10.71–19.18%) compared to 2A of restored grasslands. (3) Soil improvement effect: The contents of soil organic carbon (SOC), total phosphorus (TP), nitrate nitrogen (NN), and available phosphorus (AP) increased significantly with the restoration years (in 20A, the SOC content in the 0–10 cm soil layer increased by 57.5% compared with CK), and the soil pH gradually approached neutrality. (4) In artificial grasslands with different restoration ages (20A, 16A, and 14A), significant or highly significant correlations existed between C. alatauensis tiller characteristics and community and soil properties. In conclusion, C. alatauensis in artificial grasslands drives population enhancement, community succession, and soil improvement through patch expansion. Full article
(This article belongs to the Section Plant–Soil Interactions)
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16 pages, 2268 KB  
Article
Epichloë Endophyte Alters Bacterial Nitrogen-Cycling Gene Abundance in the Rhizosphere Soil of Perennial Ryegrass
by Munire Maimaitiyiming, Yanxiang Huang, Letian Jia, Mofan Wu and Zhenjiang Chen
Biology 2025, 14(7), 879; https://doi.org/10.3390/biology14070879 - 18 Jul 2025
Viewed by 347
Abstract
Perennial ryegrass (Lolium perenne), an important forage and turfgrass species, can establish a mutualistic symbiosis with the fungal endophyte Epichloë festucae var. lolii. Although the physiological and ecological impacts of endophyte infection on ryegrass have been extensively investigated, the response of [...] Read more.
Perennial ryegrass (Lolium perenne), an important forage and turfgrass species, can establish a mutualistic symbiosis with the fungal endophyte Epichloë festucae var. lolii. Although the physiological and ecological impacts of endophyte infection on ryegrass have been extensively investigated, the response of the soil microbial community and nitrogen-cycling gene to this relationship has received much less attention. The present study emphasized abundance and diversity variation in the AOB-amoA, nirK and nosZ functional genes in the rhizosphere soil of the endophyte–ryegrass symbiosis following litter addition. We sampled four times: at T0 (prior to first litter addition), T1 (post 120 d of 1st litter addition), T2 (post 120 d of 2nd litter addition) and T3 (post 120 d of 3rd litter addition) times. Real-time fluorescence quantitative PCR (qPCR) and PCR amplification and sequencing were used to characterize the abundance and diversity of the AOB-amoA, nirK and nosZ genes in rhizosphere soils of endophyte-infected (E+) plants and endophyte-free (E−) plants. A significant enhancement of total Phosphorus (P), Soil Organic Carbon (SOC), Ammonium ion (NH4+) and Nitrate ion (NO3) contents in the rhizosphere soil was recorded in endophyte-infected plants at different sampling times compared to endophyte-free plants (p ≤ 0.05). The absolute abundance of the AOB-amoA gene at T0 and T1 times was higher, as was the absolute abundance of the nosZ gene at T0, T1 and T3 times in the E+ plant rhizophere soils relative to E− plant rhizosphere soils. A significant change in relative abundance of the AOB-amoA and nosZ genes in the host rhizophere soils of endophyte-infected plants at T1 and T3 times was observed. The experiment failed to show any significant alteration in abundance and diversity of the nirK gene, and diversity of the AOB-amoA and nosZ genes. Analysis of the abundance and diversity of the nirK gene indicated that changes in soil properties accounted for approximately 70.38% of the variation along the first axis and 16.69% along the second axis, and soil NH4+ (p = 0.002, 50.4%) and soil C/P ratio (p = 0.012, 15.8%) had a strong effect. The changes in community abundance and diversity of the AOB-amoA and nosZ genes were mainly related to soil pH, N/P ratio and NH4+ content. The results demonstrate that the existence of tripartite interactions among the foliar endophyte E. festucae var. Lolii, L. perenne and soil nitrogen-cycling gene has important implications for reducing soil losses on N. Full article
(This article belongs to the Collection Plant Growth-Promoting Bacteria: Mechanisms and Applications)
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