Characteristics Of Soil Organic Carbon Research Articles

Characteristics of Soil Organic Carbon and Its Influencing Factors of Different Plant Communities in the Yellow River Delta

Changes in soil organic carbon （SOC） are of great importance to the evolution of soil quality. The distribution characteristics of soil organic carbon （SOC）, easily oxidizable organic carbon （EOC）, dissolved organic carbon （DOC）, and particulate organic carbon （POC） were investigated in the 0-50 cm soil layer of the Phragmites australis, Suaeda salsa, and Tamarix chinensis communities of the supratidal zone in the Yellow River Delta as the research subjects. Then, the composition and sources of soil dissolved organic matter （DOM） were analyzed based on the UV-vis spectroscopy, three-dimensional excitation emission matrix spectroscopy, and parallel factor analysis （PARAFAC）. Finally, the key factors affecting the characteristics of soil organic carbon and DOM fractions of different plant communities were finally revealed in combination with the physicochemical properties of the soil. The results showed that： ① Comparing different communities, the S. salsa community had the highest ω（SOC） at 7.53 g·kg-1, the T. chinensis community had the highest ω（DOC） at 0.98 g·kg-1, and the P. australis community had significantly higher ω（EOC） and ω（POC） than those of the S. salsa and T. chinensis communities at 1.47 g·kg-1 and 0.65 g·kg-1, respectively. The vertical distribution showed a tendency to decrease with deeper soil layers, except for POC concentration. ② The main components of soil DOM of the P. australis, S. salsa, and T. chinensis communities were humus, protein-like substances, and fulvic acid-like substances, of which exogenous components accounted for 55.80%, 56.41%, and 52.81% in the above communities, respectively. ③ Comparing different communities, the humification degree of the P. australis community was significantly higher than that of the S. salsa and T. chinensi communities, but its aromaticity and proportion of biological sources were significantly lower than those of the T. chinensi community. On the vertical profile of the soil, DOM aromaticity and humification degree gradually increased with the deepening of the soil layer, and the deeper soils were mainly dominated by small molecular weight DOM with a lower proportion of hydrophobic fraction. ④ Redundant analysis showed that N （P<0.01）, NO2--N （P<0.01）, and NH4+-N （P<0.05） were the key factors affecting the changes in soil organic carbon and DOM fractions.

Distribution and Storage Characteristics of Soil Organic Carbon in Tidal Wetland of Dandou Sea, Guangxi

In order to study the distribution characteristics of soil organic carbon (SOC) and soil organic carbon storage (SOCS) among different wetland types in Dandou Sea tidal wetland in Guangxi, firstly, based on Sentinel–2 imaging and random forest algorithm, combined with the existing tidal wetland data, a 10 m resolution tidal wetland dataset in Guangxi from 2019 to 2023 was generated, covering mangroves, salt marshes and tidal flats. The results show that the overall accuracy of the recognition results is higher than 96%, and the Kappa coefficient is higher than 0.95, which indicates high accuracy. Subsequently, the distribution characteristics and influencing factors of SOC and SOCS in different habitats were analyzed. The results showed that the SOC content of mangroves and salt marshes was higher than that of tidal flats. The SOC content of mangrove, salt marshes and tidal flats in 0–60 cm soil layer was 5.30–10.42 g/kg, 7.60–9.84 g/kg, and 1.29–2.25 g/kg, respectively. The changes of SOCS were 12.41–26.48 t/ha, 19.58–24.15 t/ha, and 3.61–6.86 t/ha, respectively. With the increase of soil depth, the SOC and SOCS of mangroves decreased gradually, and the SOC and SOCS of salt marshes increased gradually, and SOC and SOCS were mainly affected by soil bulk density (BD), soil moisture content (MC) and pH.

Vertical distribution characteristics of soil organic carbon and vegetation types under different elevation gradients in Cangshan, Dali.

The Cangshan National Nature Reserve of Dali City was adopted as the research object to clarify the vertical distribution characteristics of soil organic carbon (SOC) and vegetation types at different elevations in western Yunnan. The contents of SOC, light fraction organic carbon (LFOC), heavy fraction organic carbon (HFOC), and water-soluble organic carbon (WSOC) in the 0-30 cm soil layer at different elevations (2,400, 2,600, 2,800, 3,000, 3,200, 3,400, and 3,600 m) were determined, and the above-ground vegetation types at different elevations were investigated. Results showed that the SOC content was the highest in 0-20 cm surface soil and gradually decreased with the deepening of the soil layer. It increased then decreased with the increase in elevation, and it peaked at 3,000 m. The LFOC content was between 1.28 and 7.3515 gkg-1. It exhibited a decreasing trend and little change in profile distribution. The HFOC content ranged between 12.9727 and 23.3708gkg-1; it increased then decreased with the increase in profile depth. The WSOC content was between 235.5783 and 392.3925 mgkg-1, and the response sensitivity to elevation change was weak. With the increase in elevation, WSOC/SOC and LFOC/SOC showed a similar trend, whereas HFOC presented an opposite trend. This observation indicates that the active organic carbon content at 3,600 m was lower than that at 2,400 m, and the middle elevation was conducive to the storage of active organic carbon. Meanwhile, the physical and chemical properties of soil affected the distribution of organic carbon to a certain extent. The vegetation type survey showed that the above-ground dominant species within 2,400-2,800 m were Pinus yunnanensis and Pinus armandii. Many evergreen and mixed coniferous broadleaf forests were distributed from 3,000 m to 3,200 m. Species of Abies delavayi were mainly distributed from 3,400m to 3,600m. This research serves as a reference for the study of forest soil carbon stability in high-elevation areas and plays an important role in formulating reasonable land use management policies, protecting forest soil, reducing organic carbon loss, and investigating the carbon sequestration stability of forest ecosystems.

Change Characteristics of Soil Organic Carbon and Soil Available Nutrients and Their Relationship in the Subalpine Shrub Zone of Qilian Mountains in China

Studying the spatial and temporal distribution of soil organic carbon (SOC) content in high-altitude mountainous areas and its correlation with soil nutrients provides a basis for understanding soil carbon stocks and the factors affecting the local carbon cycle. Based on soil samples collected from a semi-sunny slope and semi-shady slope in the subalpine shrub zone of the eastern Qilian Mountains from May to October 2019, we studied the temporal and spatial changes in SOC and soil available nutrients and their relationships. The results showed that SOC content and soil nutrients were greater on the semi-shady slope than on the semi-sunny slope during the growing season and decreased with an increase in soil depth in different slope directions, showing obvious surface aggregation. The soil available nitrogen (SAN) content was consistent with the SOC content and exhibited greater synchronization. SOC was significantly positively correlated with soil available nutrients in the study area during the whole growing season. However, the correlation between SOC and soil nutrients varied among the different soil layers and slope orientations. The SOC content was more obviously correlated with the SAN content in the soil layer at a depth of 30–40 cm (r = 0.67, p &lt; 0.05) on the semi-shady slope. The SOC content was more obviously correlated with soil-available phosphorus (SAP) content in the soil layer at a depth of 30–40 cm (r = 0.57) on the semi-sunny slop. The SOC content was more obviously correlated with the SAP content in the soil layer at a depth of 60–70 cm (r = 0.55) and with the soil-available potassium (SAK) content in the soil layer at a depth of 70–80 cm (r = 0.84) on the semi-sunny slope.

Preliminary investigation of soil organic carbon distribution and turnover patterns, and potential pollution sources in and around a typical coking plant in North China

The variation characteristics of soil organic carbon (SOC) in and around the coking plant area are still unclear. In this work, the concentration and stable carbon isotope composition of SOC in coke plant soils were investigated to preliminarily identify the sources of SOC in and around the plant area, and to characterize soil carbon turnover. Meanwhile, the carbon isotopic technique was used to initially identify the soil pollution processes and sources in and around the coking plant area. The results demonstrate that the SOC content (12.76 mg g−1) of the surface soil in the coking plant is about 6 times higher than that outside the coking plant (2.05 mg g−1), and the variation range of δ13C value of the surface soil in the plant (−24.63～-18.55‰) is larger than that of the soil outside the plant (−24.92～-20.22‰). The SOC concentration decreases gradually from the center of the plant outward with increasing distance, and the δ13C in the middle and north of the plant tends to be positive compared with the δ13C in the west and southeast of the plant. As the increase of soil depth, the SOC content and δ13C value in the plant increases. On the contrary, δ13C value and SOC content outside the plant decreases, with a minor variation. Based on the carbon isotope method, the SOC in and around the coking plant area is mainly from industrial activities (e.g., coal burning and coking), and partly from C3 plants. Notably, organic waste gases containing heavy hydrocarbons, light oils, and organic compounds accumulated in the northern and northeastern areas outside the plant due to south and southwest winds, which may pose an environmental health risk.

Soil C, N and P stoichiometry in different forest stand types in the middle and lower reaches of the Beijiang River, China.

We examined the vertical distribution characteristics of soil organic carbon (C), total nitrogen (N), total phosphorus (P) and their ecological stoichiometric ratios in 0-80 cm soil profile under three forest stand types in the middle and lower reaches of the Beijiang River, including broad-leaved forest, coniferous forest, and mixed coniferous and broad-leaved forest. The results showed that soil C, N and P contents of the three forest stand types were 12.17-14.25, 1.14-1.31, and 0.27-0.30 g·kg-1, respectively. The contents of C and N decreased with the increases of soil depth. The content of C and N in each soil layer showed that coniferous and broad-leaved mixed forest > coniferous forest > broad-leaved forest. There was no significant difference in P content among the three stand types, and there was no obvious variation in the vertical profile. The soil C/N, C/P, and N/P of the three forest types were 11.2-11.3, 49.0-60.3, and 4.5-5.7, respectively. There was no significant difference in soil C/N among the three stand types. The highest soil C/P and N/P were found in the mixed forest. There was no interaction between soil depth and stand type in affecting soil C, N, P contents and their stoichiometric ratios. There was significant positive correlation between C and N, and between N and C/P in each stand type and soil layer. Soil C/P and N/P had stronger ecological indicating effects on stand types. The coniferous and broad-leaved mixed forest was strongly limited by P availability.

Soil organic carbon distribution and factors affecting carbon accumulation in natural and plantation forests in tropical China

Tropical rainforests are the most complex forest ecosystem in the world, and play an important role in the global carbon cycle. To investigate the accumulation characteristics of soil organic carbon (SOC) in tropical rainforests of different origins, soil samples from plantation and natural forests of tropical mountain rainforests in Wuzhi Mountain (WM), Qixian Mountain (QM) and Diaoluo Mountain (DM) in eastern Hainan Island, China, were collected at various depths (0–10, 10–30 and 30–50 cm). SOC concentrations of different-forest-origin soils were analysed and compared, and the effects of soil physicochemical parameters on SOC concentration in natural and plantation forests were investigated. SOC concentrations in plantation forests in WM, QM and DM were higher than those in natural forests, although the difference was not statistically significant. In the 0–50 cm soil depth, the SOC concentrations of different-forest-origin soils decreased with increasing soil depth, with SOC concentrations in the surface layer (0–10 cm) of natural forests being significantly higher than those in the middle layer (10–30 cm) and bottom layer (30–50 cm) (P < 0.05). Natural forests have lower pH than plantation forests. Correlation analysis revealed significant negative correlation (P < 0.05) between SOC concentration in both forest origins and soil pH. The proportion of clay and silt is greater in natural forests than in plantation forests, but the proportion of sand is greater in plantation forests.

Characteristics of Soil Organic Carbon (SOC) Loss with Water Erosion in Sloping Farmland of Southwestern China during Maize (Zea mays L.) Growth Stages

Due to frequent human disturbance and the influence of crop growth and development, the migration of soil organic carbon (SOC) in sloping farmland is considerably different to those in other ecosystems. The impacts of maize over its entire growth period on the SOC loss in sloping farmland on purple soils under different erosion stages were investigated, in 2016. This was undertaken using rainfall simulation tests on 15° slopes with a rainfall intensity of 1.5 mm·min−1, in Sichuan Province, China. In this study, erosion development, fluctuating increasing trends in the surface runoff yield, interflow runoff yield, sediment yield, and dissolved organic carbon (DOC) migration flux were observed. Opposite trends were observed in the DOC mass concentration, total soil organic carbon (TOC) content of the sediment, the SOC content of sediment particle state, the DOC content of the sediment, and the SOC enrichment ratio. The DOC migration flux in the surface runoff and in interflow of the rill erosion stage was 1.39–2.84, 3.22–7.78 times significantly higher than that of the sheet erosion stage at each maize growth stage, respectively (p &lt; 0.05). The average DOC mass concentration in the surface runoff, the total DOC content of the sediment, and the SOC enrichment ratio in the sheet erosion stage increased by 100.58–146.44%, 44.44–126.15%, 141.32–191.26%, respectively, compared with the rill erosion stage. Under the experimental conditions, we found that DOC loss mainly occurred at the seedling and mature stages for maize. We also found that maize growth could promote the production of soil interflow, leading to intense soil loss occurring at the subsurface. Compared with DOC mass concentrations in the surface runoff, there was an increase of 4.90–28.29% in the soil interflow, indicating that soil interflow plays a more important role in DOC loss. The growth of maize could impact formation of surface runoff and interflow, reducing the loss of SOC caused by soil erosion. This study helps to understand the carbon loss process in agricultural production in purple soil areas.

Mineralization Characteristics of Soil Organic Carbon and Its Relationship with Organic Carbon Components in Artificial Robinia pseudoacacia Forest in Loess Hilly Region

In order to explore the characteristics of organic carbon mineralization and the variation law of organic carbon components of an artificial forest in a loess hilly area, an artificial Robinia pseudoacacia forest restored for 13 years and the adjacent slope farmland were selected as the research objects, and indoor culture experiments under three different temperature treatments (15, 25, and 35℃) were carried out. The results indicated that the mineralization rate of soil organic carbon decreased sharply at first and then stabilized. The cumulative release of organic carbon increased rapidly in the initial stage of culture and gradually slowed in the later stage. Soil organic carbon mineralization in sloping farmland was more sensitive to temperature change, and its temperature sensitivity coefficient Q10 was 1.52, whereas that in R. pseudoacacia forest land was only 1.38. According to the fitting of the single reservoir first-order dynamic equation, the soil mineralization potential Cp of R. pseudoacacia forest land and slope farmland was between 2.02-4.32 g·kg-1 and 1.25-3.17 g·kg-1, respectively, that is, the mineralization potential of the R. pseudoacacia forest was higher. During the cultivation period, the content of various active organic carbon components decreased with time, and that in the R. pseudoacacia forest land was greater than that in the slope land. The cumulative carbon release of soil was significantly positively correlated with the contents of MBC and DOC (P<0.05), and Q10 (15-25℃) was negatively correlated with the contents of SOC, EOC, and SWC (P<0.05). These results could provide some reference for the study of soil carbon sequestration in loess hilly regions under climate change.

Characterisation of organic carbon distribution and turnover by stable carbon isotopes in major types of soils in China

Environmental context Soil carbon sequestration plays an important role in achieving the goal of carbon neutrality. We studied the characteristics of organic carbon distribution and sequestration by stable carbon isotopes in nine types of soils in China and found that macro-aggregates possessed more organic carbon with a low degree of decomposition, while the overall direction of organic carbon transfer between aggregates was from macro-aggregates through micro-aggregates to the grain-size fractions of chalky clay. These results provide a foundation for understanding soil carbon sequestration in China’s cultivated lands. Rationale Soil is the largest carbon reservoir of terrestrial ecosystems. Studying carbon turnover in cultivated soils is vital for China to achieve its carbon neutrality goal. Methodology In this research, we investigated the distribution characteristics of soil organic carbon and its turnover among aggregates in nine major soil types in China by 13C stable isotopes. Results Since the second national soil survey in China 1979, the surface soil organic carbon (SOC) content of cultivated lands in boggy soils, black soils and dark brown forest soils in northeastern China has decreased (129.06, 2.70 and 7.78 g kg−1, respectively) while increased in cinnamon soils, brown soils, red soils, latosols, paddy soils and chestnut soils (0.85–7.79 g kg−1). Overall, the SOC content was highest in 1–0.25 mm aggregates, lowest in 0.053–0.02 mm aggregates and higher in &lt;0.02 mm aggregates. The Δ13C value showed that the silt-clay size class fraction &gt; micro-aggregates &gt; macro-aggregates. Discussion The overall turnover direction of SOC among aggregates starts from macro-aggregates to micro-aggregates and ends with the silt-clay size class fraction. The result directly confirms both the ‘hierarchical development model’ and ‘embryonic development model’ of soil aggregate formation. The SOC flow direction and mobility potential between aggregates, as indicated by Δ13C values, suggest that cultivated soils are more susceptible to soil type than wasteland soils.

宁夏草地土壤有机碳空间特征及其影响因素

PDF HTML阅读 XML下载 导出引用 引用提醒 宁夏草地土壤有机碳空间特征及其影响因素 DOI: 10.5846/stxb202201040022 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家自然科学基金项目（42061037） Spatial characteristics of soil organic carbon in grassland of Ningxia and its influencing factors Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:草地是重要的碳汇资源库，在陆地生态系统碳循环中扮演着重要角色。探明草地土壤有机碳的空间分布格局及其影响因素对于推动区域生态系统碳汇管理，实现"双碳"目标和绿色高质量发展具有重要意义。以宁夏三种主要草地类型为研究对象，基于野外样点调查，采用结构方程模型，分析了草地土壤有机碳的空间分布特征及其影响因素。结果表明：不同类型草地土壤有机碳含量表现为草甸草原高于典型草原，荒漠草原最低，垂直剖面上均随土壤深度的增加而降低。草甸草原和荒漠草原有机碳空间变异自表层向下逐渐增大，典型草原在20-40 cm土层变异系数达到最大。有机碳分布在区域上从南部六盘山山地向中部干旱风沙带逐渐降低。路矩分析发现，海拔高度、地上生物量、降水量、温度和土壤含水量可解释土壤有机碳空间变异的91.4%。海拔高度对土壤有机碳总效应最大（作用系数为0.78），海拔高度引起的降水和温度等要素区域分异间接影响土壤有机碳含量；地上生物量对土壤有机碳的直接正向效应最大（0.559）；降水量对土壤有机碳效应分为直接效应和作用于生物量及土壤含水量的间接影响；温度表现为通过生物量对土壤有机碳间接产生负向效应（-0.259）。宁夏草地土壤有机碳的空间分布主要受降水量和与其密切相关的生物量的支配作用。近20年来降水量增多和草地人为干扰减少，宁夏草地碳汇作用显著。 Abstract:Grasslands are important contributors of carbon sequestration among terrestrial ecosystems, which play an important role in the global biogeochemical cycle and energy exchange. Based on field surveys in July-August 2021, soil samples of meadow steppe, typical steppe and desert steppe in Ningxia were collected. The organic carbon contents, bulk density, total nitrogen, and pH of these soil samples were measured. We also monitored factors affecting carbon distribution such as altitude, annual precipitation, annual mean temperature, aboveground biomass and soil water content. Results indicated that content of the soil organic carbon decreased along the vertical soil profile, the average organic carbon content followed the order of meadow steppe > typical steppe > desert steppe. The distribution of grassland soil organic carbon gradually decreased from the Liupan Mountains in the south to the dry sand belt in the middle along the altitude. Soil organic carbon was significantly positively correlated with aboveground biomass, annual precipitation, altitude and soil total nitrogen density, and significantly negatively correlated with annual mean temperature (P<0.001), positively correlated with soil water content, and negatively with soil bulk density (P<0.01), and no obvious correlation with soil pH. Amos structural equation model was applied to evaluate the combined effects of environmental factors on grassland soil organic carbon. The most important factors affecting organic carbon was altitude (r=0.78), which mainly caused regional differentiation of precipitation and temperature to affect soil organic carbon indirectly; followed by aboveground biomass (r=0.559); then annual precipitation (0.539), which not only directly but also indirectly affected the soil organic carbon by altering aboveground biomass and soil water content positively. Annual mean temperature indirectly affected organic carbon negatively by influencing aboveground biomass (r=-0.259). The spatial distribution of grassland organic carbon in Ningxia was dominated by precipitation and aboveground biomass closely related to precipitation. In the past 20 years, with the increase of precipitation and the reduction of grassland anthropogenic disturbance, grassland ecosystem in Ningxia had a very significant carbon sink function. 参考文献 相似文献 引证文献

Effects of Understory Vegetation Heterogeneity on Soil Organic Carbon Components in Cunninghamia lanceolata Plantation

As one of the important factors affecting forest soil organic carbon stocks, the effect of understory vegetation types on soil organic carbon and its components was explored to provide a theoretical basis for understory vegetation management and sustainable management in plantation forests. In order to determine the characteristics of soil organic carbon and its components under different understory vegetation types in Subtropical Cunninghamia lanceolata plantation, Indocalamus tessellatus, Diplazium donianum and Oreocnide frutescenssp were taken as research objects. The mass fractions of total organic carbon, recalcitrant organic carbon, readily oxidizable organic carbon, microbial biomass carbon and dissolved organic carbon in each soil layer at 0–10, 10–20, 20–40 and 40–60 cm were measured, and the change characteristics of soil organic carbon components were also studied and compared. The results showed that: (1) The mass fractions of total organic carbon, recalcitrant organic carbon, readily oxidizable organic carbon and microbial biomass carbon in the soils of the three understory vegetation types showed significant decreasing trends along the profile, while the mass fraction of dissolved organic carbon in 0–40 cm soil layer was significantly higher than those in 40–60 cm soil layer. (2) The mass fraction of total organic carbon (5.98–20.66 g·kg−1) had no significant difference among understory vegetation types. The mass fraction and proportion of microbial biomass carbon were higher in the 0–60 cm soil layer under cover of Indocalamus tessellatus, and the mass fractions of recalcitrant organic carbon in the 20–40 cm soil layer under Indocalamus tessellatus cover (8.57 g·kg−1) was significantly higher than that of Oreocnide frutescenssp (5.73 g·kg−1). The soil layer of 0–20 cm under the Diplazium donianum community has a higher mass fraction and proportion of readily oxidizable organic carbon. (3) Correlation analysis showed that soil organic carbon and its components were positively correlated with total nitrogen, dissolved total nitrogen, dissolved organic nitrogen and microbial biomass nitrogen. There is a significant positive correlation among the components of soil organic carbon. (4) Redundancy analysis showed that soil bulk density (41.6%), microbial biomass nitrogen (41.2%), dissolved total nitrogen (43.7%), total nitrogen (9.9%), dissolved organic nitrogen (43.6%) and pH (6.6%) were the most significant environmental factors affecting organic carbon components in four soil layers. Understory vegetation type can influence the distribution characteristics of soil organic carbon components in Cunninghamia lanceolata plantation, and soil active organic carbon components are more susceptible to the influence of understory vegetation type than total organic carbon and recalcitrant organic carbon.

The Characteristics of Soil Organic Carbon (SOC) at Forest Stands of Mount-Merbabu National Park and Upland Farming

This study examines the characteristics of vegetation and SOC at forest stands of Mount-Merbabu National Park (Pine (Pinus merkusii), Puspa (Schima noronhae Theaceae), Acacia (Acacia decurren Fabaceae), Bintamin (Cupressus sp), and Mixed) and upland farming at a soil depth of 0-70 cm. Observations of characteristics of vegetation stands were made by observing plot units measuring 50 m x 50 m and three replicates, while the observations of SOC included: organic-C and bulk density soil at a depth of 0-70 cm and three replicate. The research data were analyzed descriptively, followed by the F-Test and DMRT Test at 5% level. The results showed that the SOC content decreased with increasing soil depth (0-10, 10-20, 20-30, 30-50, 50-70 cm). At soil depth (0-70 cm), the highest SOC concentration and SOC stocks were in the Puspa (53.40 g C kg−1 or 437.18 ton C ha−1), followed by Mixed (50.01 g C kg−1 or 303.62 ton C ha−1), Bintamin (28.08 C kg−1 or 198.70 ton C ha−1), Acacia (24.39 g C kg−1 or 233.94 ton C ha−1), and the lowest is Pine (20.13 g C kg−1 or 150.83 ton C ha−1); while the upland farming (15.28 g C kg−1 or 103.38 ton C ha−1). Puspa can be recommended as a good type of revegetate plant.

Soil stoichiometry characteristics under different land use types in the Horqin Sandy Land, China

The stoichiometry characteristics of carbon (C), nitrogen (N), and phosphorus (P) is an important indicator of soil quality and ecosystem nutrient limitations. Exploring the effects of land use type and soil depth on soil nutrient stoichiometry can clarify soil nutrient cycling. In this study, we collected soil samples from sites with five different land use types (irrigated cropland, rainfed cropland, sandy grassland, fixed dunes, and mobile dunes) in the Horqin Sandy Land, and evaluated the influences of land use type and soil depth on the contents and stoichiometry characteristics of soil organic carbon (SOC), total nitrogen (TN), and total phosphorus (TP). We found that: 1) SOC (3.23 g·kg-1), TN (0.37 g·kg-1), and TP (0.15 g·kg-1) contents and stoichiometry characteristics (C:N, C:P, N:P was 9.07, 25.56, 2.97, respectively) to a depth of 10 cm in the Horqin Sandy Land were significantly lower than the mean values of soils in China. 2) Soil stoichiometry characteristics differed significantly among land use types. The contents of SOC, TN, and TP to a depth of 100 cm were highest in irrigated cropland, followed by sandy grassland, rainfed cropland, fixed dunes, and mobile dunes. The C:N ratios in sandy grassland, irrigated cropland, and rainfed cropland were significantly higher than those in the fixed dune and mobile dune sites. C:P ratios in the sandy grassland, fixed dunes, irrigated cropland, and rainfed cropland were significantly higher than that in the mobile dunes. The N:P ratio differed little among the five land use types. 3) SOC and TN contents in the sandy grassland, fixed dunes, irrigated cropland, and rainfed cropland decreased with increasing soil depth. SOC, TN, and C:P in the mobile dunes and TP and C:N in all land use types showed no variation among depths. The C:P ratio of sandy grassland, fixed dunes, irrigated cropland, and rainfed cropland and the N:P ratio of sandy grassland decreased with increasing soil depth. 4) SOC, TN, and TP contents and the C:N ratio were significantly negatively correlated with the contents of medium and fine sands and with soil bulk density, but significantly positively correlated with silt+clay, and very fine sand contents. Desertification led to losses of SOC and nutrients in the Horqin Sandy Land, and exacerbated soil N deficiency. Inputs of water and ferti-lizer helped cropland to maintain a relatively high level of soil nutrients.

Characteristics of Soil Organic Carbon in Croplands and Affecting Factors in Hubei Province

SOC storage (SOCS) plays a vital role in global climate change. Understanding the spatial pattern and features of soil organic carbon (SOC) and its influencing factors is important for increasing SOC fixation. However, few studies exist on the organic carbon reserves of farmland on a regional scale. This study revealed the SOCD and SOCS values and distribution using Hubei Province as a sampling region. The results demonstrated that the spatial distributions of farmland system carbon storage and density were uneven, and the spatial heterogeneity was related to geography, cultivated area, and soil type. The SOCD ranged from 0.559 to 10.613 kg/m2, with an average of 3.3710 ± 0.0337 kg/m2, and the soil carbon reserve of the farmland system was ~17.81 Tg. The SOCD varied with topography and soil type: in mountainous cultivated land, it was generally higher than that in hilly land and in the plains. However, the plain cultivated areas contained the highest carbon reserves. Within the farmland system, paddy soil, the dominant soil type, exhibited higher SOCD and larger SOC storage capacity. Soil types with the same physicochemical properties exhibited different organic carbon storage capacity in different geomorphic and regional environments. Specifically, paddy soil was found to have higher SOCD and SOCS than the other soil types, and its soil carbon storage capacity was high; the SOC reserves of wheat-rice tillage were the largest among the main tillage methods. Boosting the soil carbon sink requires fundamental improvement in soil properties by improving soil texture, using conservation tillage to increase soil organic matter, and reducing unnecessary human interference.

Relationship between Soil Organic Carbon, Soil Nutrients, and Land Use in Linyi City (East China)

The distribution characteristics of soil organic carbon (SOC) and soil nutrients under different land-use types in Linyi City, East China, were studied. The spatial distribution of SOC under different land-use types and the relationship between SOC and soil nutrients were analyzed using remote sensing interpretation and soil sample analyses. The results showed that SOC in Linyi was mainly stored in drylands and paddy fields. SOC and total nitrogen (TN) levels were positively correlated for most land use types. There was a positive linear correlation between SOC and total K in the paddy fields. The coefficients of variation for SOC and TN differed greatly among the land use types studied. Total SOC storage was 8772.73 × 103 kg in the surface 0.2 m soil layer. The order of total SOC storage was drylands (6771.45 × 103 ton) &gt; paddy field (764.67 × 103 ton) &gt; nurseries (510.79 × 103 ton) &gt; forest land (413.49 × 103 ton) &gt; low-cover grasslands (238 × 103 ton) &gt; bare land (74.35 × 103 ton). With the largest SOC storage, and C density, respectively, drylands and paddy fields are conducive to enhancing soil C sequestration, achieving low-carbon goals, and mitigating climate change.

Molecular-level characteristics of soil organic carbon in rhizosheaths from a semiarid grassland of North China

Rhizosheaths are aggregated, sheath-like soils that physically adhere to root surface, and they form on herbaceous plant roots worldwide, especially in semiarid grasslands. Representing a strong root−soil−microbe interaction, the rhizosheaths are expected to have distinct soil organic carbon (SOC) signatures from rhizosphere soils of non-rhizosheath forming plants. However, such signatures remain unclear, which hinders our understanding of root effects on SOC cycling in grasslands. We compared SOC characteristics between rhizosheath and non-rhizosheath soils of eight herbaceous plant species, collected from a semiarid grassland of North China, using solid-state 13C nuclear magnetic resonance spectroscopy and biomarker analyses. We further examined the temporal dynamics of SOC characteristics of rhizosheath soils from early, middle, and late plant growth stages. Compared to non-rhizosheath SOC, rhizosheath SOC had more root inputs of both labile substrates (carbohydrates and free alkanoic acids) and relatively recalcitrant suberin- and lignin-derived compounds. Moreover, the labile inputs provided more substrates for microbial degradation of cutin-derived compounds. These indicators of labile substrate availability increased significantly from the early to late growth stages. Overall, our findings clarify the molecular characteristics of rhizosheath SOC and its temporal dynamics, both of which suggest a critical role of rhizosheath in shaping the rhizosphere microenvironment and regulating SOC cycling.

Effects of Organic Fertilizer Replacing Chemical Fertilizer on Organic Carbon Mineralization and Active Organic Carbon in Dryland Yellow Soil

At present, the effect characteristics and mechanism of organic fertilizer replacing chemical fertilizer on organic carbon mineralization and active organic carbon in dryland yellow soil remain unclear. In order to explore the effect of organic fertilizer replacing chemical fertilizer on organic carbon mineralization and active organic carbon in dryland yellow soil, we used soil with no fertilization (CK), only chemical fertilizer (NP), 50% organic fertilizer replacing chemical fertilizer (1/2(NPM)), and 100% organic fertilizer replacing chemical fertilizer (M). We examined the indoor mineralization culture of organic carbon and explored the characteristics of soil organic carbon and the change in active organic carbon under the condition of organic fertilizer replacing chemical fertilizer. The results showed that organic fertilizer replacing chemical fertilizer increased soil pH, organic carbon (SOC), total nitrogen (TN), and C/N. During the culture period, the soil organic carbon mineralization rate of all treatments decreased sharply in the initial stage (2-4 days), decreased slightly in the middle stage (4-20 days), and tended to be stable in the last stage (20-60 days). After fertilization, the cumulative mineralization of soil organic carbon significantly increased by 7.9%-27.7%. Compared with that in the NP treatment, the cumulative mineralization of soil organic carbon decreased by 5.2% in the 1/2(NPM) treatment and increased by 12.2% in the 1/2(NPM) treatment. Before mineralization culture, the substitution of organic fertilizer for chemical fertilizer had no significant effect on soil recalcitrant organic carbon (ROC) but significantly increased the content of microbial biomass carbon (MBC). The content of dissolved organic carbon (DOC) was significantly increased in the 1/2(NPM) treatment and decreased in the M treatment. After 60 days of culture, the content of soil active organic carbon in all treatments decreased compared with the initial content, of which MBC decreased the most (30.6%-41.2%). The accumulated mineralization of organic carbon was significantly positively correlated with soil pH and SOC and significantly positively correlated with the initial value of MBC and the change value before and after culture. To summarize, 100% organic fertilizer replacing chemical fertilizer significantly promoted soil organic carbon mineralization and reduced soil organic carbon stability; 50% organic fertilizer replacing chemical fertilizer inhibited soil organic carbon mineralization, which was beneficial to soil sequestration and fertilization; and 50% organic fertilizer replacing chemical fertilizer significantly increased soil active organic carbon content, and MBC was used as the main carbon source in the process of soil organic carbon mineralization.

黄土丘陵区退耕小流域土壤有机碳分布特征及地形植被对其的影响

PDF HTML阅读 XML下载 导出引用 引用提醒 黄土丘陵区退耕小流域土壤有机碳分布特征及地形植被对其的影响 DOI: 10.5846/stxb202107081840 作者: 作者单位: 作者简介: 通讯作者: 中图分类号: 基金项目: 国家重点研发计划项目（2021YFD1900700）；陕西省杰出青年科学基金项目（2021JC-19） Distribution characteristics of soil organic carbon and the effect of topographic and vegetation on small watershed of returned farmland in the loess hilly region Author: Affiliation: Fund Project: 摘要 | 图/表 | 访问统计 | 参考文献 | 相似文献 | 引证文献 | 资源附件 | 文章评论 摘要:针对黄土丘陵区退耕还林（草）工程实施20年固碳效果研究薄弱的问题，以典型退耕小流域为对象，在不同地形（峁坡、沟肩、沟谷）和植被类型（次生草地、撂荒山杏林、撂荒坡耕地）共布设147个样点采集0-100 cm土层样品并测定，以研究土壤有机碳（SOC）分布特征及地形、植被对其的影响。结果表明：小流域峁坡剖面（0-100 cm）土层SOC含量平均为2.43 g/kg。地形和植被类型对小流域SOC分布特征产生了重要影响：沟肩表层和剖面SOC含量均最高且显著（P<0.05）高于沟谷，但与峁坡无显著差异；次生草地表层（0-20 cm）和亚表层（20-40 cm） SOC含量均显著（P<0.05）高于撂荒山杏林和撂荒坡耕地。地统计学分析显示小流域0-20 cm土层SOC含量有最大块金值且块金系数为49.6%，即表层SOC具有最大块金效应且受到结构因素与随机因素共同影响；剖面SOC分布格局表现出与表层土壤相似的特征。总之，退耕还林（草）碳汇效应显著，且在地形和植被类型作用下呈现显著的空间异质性特征。 Abstract:The "Grain to Green" project has been implemented for more than 20 years in the loess hilly region. However, its carbon sequestration effect is rarely evaluated. To this end, a total of 147 sample sites were collected in different topography (hillslope, gully shoulder, and gully) and vegetation types (secondary grassland, abandoned apricot forest, and abandoned slope cropland) in a small watershed in the region to collect samples from 0-20 cm, 20-40 cm, 40-60 cm, 60-80 cm and 80-100 cm soil layers. The distribution characteristics of soil organic carbon (SOC) and the influence of topography and vegetation were studied by statistics and geostatistics. The results showed that the average SOC content in the 0-100 cm profile of Xifuzigou watershed was 2.43 g/kg. Topography and vegetation types had important effects on the distribution characteristics of the SOC in small watershed. The SOC content in the surface and profile of gully shoulder was the highest and significantly higher (P<0.05) than gully, but had no significant difference with hillslope. The SOC in the surface layer (0-20 cm) and subsurface layer (20-40 cm) of the secondary grassland was significantly higher (P<0.05) than that of abandoned apricot forest and abandoned slope cropland. Geostatistical analysis showed that the 0-20 cm soil layer had the largest nugget and the nugget coefficient was 49.6%, and the 0-100 cm profile's nugget coefficient was 15.7%. The results indicated that the surface SOC had the largest nugget effect and was influenced by both structural and random factors, and the profile SOC had strongly spatial correlation which distribution was dominated by structural factors. The distribution pattern of the SOC in 0-100 cm profile was similar to that in surface soil which high values of SOC content were distributed in the secondary grassland and abandoned apricot forest, while the low values were mainly in abandoned slope cropland and dam land. At the small watershed scale, the distribution of SOC was consistent with vegetation types, but had no significant correlation with microtopography (slope, aspect and position), which indicated that the land-use/land cover dramatic changes weakened the effect of topography on SOC distribution. However, the results cannot reflect the carbon sequestration effect in the region because there are great differences in landform in the loess hilly region, and the implementation of the project varies greatly in shape and form. In conclusion, the carbon sink effect of "Grain to Green" is significant, and presents significantly spatial heterogeneity under the effect of terrain and vegetation type. 参考文献 相似文献 引证文献

Mechanism and Evolution of Soil Organic Carbon Coupling with Rocky Desertification in South China Karst

To study the spatial distribution characteristics of soil organic carbon (SOC) coupled with rocky desertification, 1212 soil samples from 152 soil profiles were sampled from different karst landforms, including karst low hills/virgin forest (KLH) in Libo County, a karst peak-cluster depression (KPCD) in Xingyi County, a karst canyon (KC) in Guanling County, a karst plateau basin (KPB) in Puding County and a karst trough valley (KTV) in Yinjiang County. The spatial distribution characteristics of the responses of SOC, SOC density (SOCD), rocky desertification and soil bulk density (SBD) to different influencing factors were analyzed. The relationships among SOC, SOCD, rocky desertification and SBD were analyzed using Pearson correlation analysis. The SOC storage capacity was characterized by using SOCD, and then the SOC storage capacity in different evolution stages of karst landforms was assessed. The SOC contents of KLH, KPCD, KC, KPB and KTV ranged from 6.16 to 38.20 g·kg−1, 7.42 to 27.08 g·kg−1, 6.28 to 35.17 g·kg−1, 4.62 to 23.79 g·kg−1 and 5.24 to 37.85 g·kg−1, respectively, and their average SOCD values (0–100 cm) were 7.37, 10.79, 7.06, 8.51 and 7.84 kg·m−2, respectively. The karst landforms as ordered by SOC storage capacity were KPCD &gt; KPB &gt; KLH &gt; KTV &gt; KC. The SOC content was negatively correlated with the SBD; light rocky desertification may lead to SOC accumulation. The rocky desertification degree and SBD were closely associated with slope position and gradient. Rocky desertification first increased, then decreased from mountain foot to summit, and increased with increasing slope gradient. However, the SBD decreased from mountain foot to summit and with increasing slope gradient. The SOC contents on the northern aspect of the mountains were generally higher than the other aspects. In summary, rock outcrops controlled the SOC contents in the studied regions. The slope position, gradient and aspect influenced the composition and distribution of vegetation, which influenced the evolution of rocky desertification. Therefore, these factors indirectly affected the SOC content. Additionally, the SOCD decreased with increasing rocky desertification. During the different evolution stages of karst landforms, the SOC storage capacity first decreases, then increases.