• Good News: 243 Papers from the 'Journal of Soil and Water Conservation' Included in CNKI's High-Impact Paper List
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    Volume 37,  2023 Issue 6
    • JIANG Kaixin, MO Shuhong, YU Kunxia, LI Zhanbin

      2023,37(6):1-10, DOI: 10.13870/j.cnki.stbcxb.2023.06.001

      Abstract:

      Yudiba dam serves as an effective measure for controlling gully erosion and mitigating soil and water loss in the Loess Plateau. Its role in reducing sediment yield and transport in watersheds is achieved by temporarily obstructing or slowing down floodwaters, thereby retaining sediment and preventing silting into the river. With the ecological protection of the basin becoming more and more scientific and reasonable, it is necessary to quantitatively and accurately analyze the sediment retention of Yudiba dams in different stages in order to evaluate their real and specific benefits in the control of water and soil loss, which can provide a reference for the precise implementation of high-quality development in the Yellow River Basin. By consulting the literature and data of related research on Yudiba dams at home and abroad, combined with field investigation and sampling, laboratory instrument testing and subsequent related research experience, this paper systematically summarizes seven methods for analyzing the sediment retention of Yudiba dams: field investigation, topographic mapping method, mathematical attribution method, cause analysis method, weight coefficient method, model simulation method and dating analysis in fingerprint identification technology. The principle, steps, applicability and problems to be solved of each method are described, and the follow-up sediment retention analysis of Yudai Dam is prospected, with a view to providing reference for further accurate quantitative analysis of sediment retention of Yudiba dams.

    • ZHENG Jinde, PAN Yanfei, XU Qinxue, FANG Rongjie, ZHANG Shuaipu, FU Zhiyong

      2023,37(6):11-17, DOI: 10.13870/j.cnki.stbcxb.2023.06.002

      Abstract:

      In order to investigate the characteristics of rainfall erosion of young citrus orchards on calcareous soil and red soil slopes in karst areas of northwestern Guangxi, an indoor artificial simulated rainfall experiment was conducted to study the runoff and sediment yield characteristics of young citrus orchards on calcareous soil and red soil slopes under three rainfall intensities (30, 60, and 90 mm/h). The results showed that: (1) When the rainfall intensity was 30 and 60 mm/h, the total runoff yield of red soil citrus orchards was 2.46 and 1.83 times that of calcareous soil citrus orchards, respectively, and the red soil citrus orchards was dominated by surface runoff yield, while the calcareous soil citrus orchards was dominated by subsurface flow yield; when the rainfall intensity was 90 mm/h, there was no significant difference in the total amount of runoff between the two (p>0.05), and both of them were mainly by surface runoff. (2) The surface runoff intensity of calcareous soil citrus orchards and red soil citrus orchards increased with the increase of rainfall intensity. However, with the increase of rainfall intensity, the subsurface flow intensity of calcareous soil citrus orchards showed a trend of first increasing and then decreasing, while the subsurface flow intensity of red soil citrus orchards was decreasing. (3) When the rainfall intensity was 60 mm/h, the total sediment yield of red soil citrus orange orchards was 3.74 times that of the calcareous soil citrus orchards, and when the rainfall intensity was 90 mm/h, the total sediment yield of the calcareous soil citrus orchards was 2.86 times that of red soil citrus orchards. During the rainfall process, the sediment yield of calcareous soil citrus orchards fluctuates sharply with the increase of rainfall duration, while the sediment yield of red soil citrus orchards was relatively small with the increase of rainfall duration. (4) When the rainfall intensity was more than 60 mm/h, there was a significant linear relationship between the cumulative sediment yield and cumulative runoff yield of calcareous soil and red soil orchards, and the greater the rainfall intensity, the more obvious the linear relationship was. The research results can provide reference and reasonable suggestions for the prevention and control of soil erosion in young citrus orchards on calcareous soil and red soil slopes in karst areas.

    • GU Fangzheng, ZHANG Huilan, WANG Linghan, XIA Shaoqin, SUN Hu

      2023,37(6):18-24,33, DOI: 10.13870/j.cnki.stbcxb.2023.06.003

      Abstract:

      Roughness is a key factor affecting the hydrodynamic characteristics of overland flow. In order to explore the hydraulic characteristics of overland flow under the influence of gradient roughness, using particle image velocimetry (PIV) to observe and analyze the velocity profile, turbulence intensity, Reynolds stress and wall shear stress of the overland flow under the three groups of flow rates. The results showed that: (1) The flow velocity decreased with the increase of roughness; the logarithmic formula of velocity distribution was obtained by fitting the dimensionless velocity. The increase of roughness was inversely proportional to the fitting constant A and proportional to the integral coefficient B. (2) The trend of streamwise turbulence intensity of gradient surface roughness was similar to that of smooth bed slope. The streamwise turbulence intensity decreased with the increase of relative water depth. With the increase of roughness, there was a nonsignificant difference in the intensity of streamwise turbulence. The turbulence intensity under the gradient rough bed was consistent with the Nezu empirical formula, and the flow rate was proportional to the empirical coefficient. (3) Under different flow rates, the Reynolds stress distribution of the graded rough bed was similar to that of the smooth bed. Under the influence of roughness, the maximum Reynolds stress appeared at y/H = 0.2~0.4. With the increase of roughness, the wall shear stress increased gradually. The synthesis showed that the method of increasing PIV resolution could be applied to the study of hydraulic characteristics of overland flow. Exploring the influence of gradient roughness on slope flow and exploring the hydrodynamic characteristics of slope flow provide new ideas for theoretical research of soil and water conservation.

    • LU Chao, MAZHOU Jiatai, LI Jiahui, ZHANG Kuandi

      2023,37(6):25-33, DOI: 10.13870/j.cnki.stbcxb.2023.06.004

      Abstract:

      In order to reveal the change mechanism of soil erosion resistance in seasonal freeze-thaw region and determine the main controlling factors affecting soil erosion resistance, the Loess soil (SM silty loam), Aeolian sandy soil (WS sandy loam) and Black soil (KS clay loam) were studied by indoor freeze-thaw simulation, flume erosion test and soil shear test. The results showed that: (1) With the increase of freeze-thaw cycles, the value of rill erodibility gradually increased, while the critical shear stress decreased. After ten freeze-thaw cycles, the rill erodibility of SM silty loam, WS sandy loam and KS clay loam increased by 76%, 63% and 11%, respectively, and the critical shear stress decreased by 37%, 13% and 91%, respectively. (2) Rill erodibility decreased with the increase of soil shear strength, cohesion and internal friction angle, while the critical shear stress showed the opposite trend. Compared with the internal friction angle, cohesion was more suitable to characterize soil erosion resistance. The rill erodibility of SM silty loam, WS sandy loam and KS clay loam was predicted by cohesion, and the determination coefficients R2 were 0.42, 0.78 and 0.50, respectively, with an average of 0.57. The prediction effect on the critical shear stress was poor, and R2 were 0.16, 0.14 and 0.18, respectively, with an average of only 0.16. (3) According to the results of Pearson correlation analysis, the prediction models of rill erodibility (R2=0.85) and critical shear stress (R2=0.79) were established based on initial soil moisture content, freeze-thaw cycles, mechanical properties and soil parameters, respectively. Studies have shown that the effects of freeze-thaw cycles on soil erosion are enormous in areas with seasonal freeze-thaw region. The findings can serve as a reference for optimizing soil and water conservation practices and controlling soil erosion across different regions.

    • GAO Ziqi, Lü Liqun, MA Chao, ZHOU Guanyu, HUANG Feng, TAO Zhengxiang, LIANG Jinhang

      2023,37(6):34-41, DOI: 10.13870/j.cnki.stbcxb.2023.06.005

      Abstract:

      In order to study the division of debris flow vulnerability and the sensitivity evaluation of environmental factors, 9 environmental factors, including precipitation, elevation, slope, aspect, runoff, lithology, fault, normalized differential vegetation index and soil erosion modulus, were selected to evaluate the vulnerability of 187 debris flow gullies based on the maximum entropy (Maxent) model. The results showed that the main factors leading to debris flow were runoff, elevation, precipitation, lithology, fault, slope, normalized differential vegetation index, soil erosion modulus and slope aspect. Based on the probability of debris flow hazards, the vulnerability zoning was carried out. It was found that the Gongshan Derung and Nu Autonomous County-Fugong section had the highest vulnerability, with an AUC of 0.974 and a standard deviation of 0.010. The results of the model analysis were consistent with the actual results. Compared with mountain torrents, the sensitivity of debris flow to environmental factors is more complex than that of mountain torrents. The reason of the complex sensitivity of environmental factors of debris flow is proved by the method of energy analysis. Runoff energy is shown to have the highest contribution to the formation of disasters in the Salween River Grand Canyon Debris.

    • YU Kunxia, LI Xue, XU Bingxiang, LI Zhanbin, LI Peng, ZHANG Guojun, ZHANG Xiaoming, ZHAO Yang, MA Wentao

      2023,37(6):42-49, DOI: 10.13870/j.cnki.stbcxb.2023.06.006

      Abstract:

      In order to analyze the impact of climate change and ecological construction measures such as vegetation and silt dams on runoff changes, the Qingshui River and Kushui River, typical watersheds into the Yellow River in Ningxia, were selected as the research objects. The Pettitt mutation method were used to detect the change points of meteorological, hydrological, and ecological construction measure series, and the multivariate linear regression equations between the land surface parameter and ecological construction measures were constructed, rainfall runoff model coupled ecological construction measures was derived based on the Budyko theory, the applicability of the model was evaluated, and the elastic coefficient method was used to quantify the contribution rate of different ecological construction measures to runoff changes. The results indicated that the runoffs in the study watersheds showed decreasing trends, and the change points of annual runoff occurred around 2000. The land surface parameters had significant positive correlations with the NDVI and silt dam index, and the simulated values from the rainfall-runoff model constructed by the introduction of the NDVI and the silt dam index are close to the observed values. The contribution rate of ecological construction measures to the reduction of runoff was as high as 78.5% in the Qingshui River basin, and vegetation and silt dams contributed 23.11% and 46.50%, respectively. The impact of ecological construction measures on runoff was much greater than that of climate change. The contribution rate of rainfall to runoff reduction in the Kushui River Basin can reach 47.30%, and the contribution rate of ecological construction measures was 59.57%, with vegetation and silt dams contributing 18.57% and 13.96% respectively, while the contribution rate of other ecological construction measures to the reduction of runoff was 27.04%. Ecological construction was the main driving factor causing changes in runoff in the Ningxia Yellow River Basin. The research results can provide theoretical support for optimizing the layout of ecological construction in Ningxia.

    • ZHU Qiming, LIU June, ZHOU Zhengchao

      2023,37(6):50-56,64, DOI: 10.13870/j.cnki.stbcxb.2023.06.007

      Abstract:

      In order to reveal the spatial distribution characteristics and influencing factors of soil erodibility (K-factor) on the Loess Plateau, this research estimated the values of K-factor on the Loess Plateau based on EPIC model, geometric mean grain size model and Torri model. The impacts of soil physical and chemical properties, elevation, slope, and other factors on the spatial distribution of K-factor were compared using geographic detectors. The findings indicated that: (1) The mean values of K-factor on the Loess plateau estimated by EPIC model, geometric mean grain size model, and Torri model were 0.036, 0.034 and 0.041, respectively. The dominant soils on the Loess Plateau exhibited medium erodibility and medium-high erodibility, with significant differences in the estimated K-factor values among the models (F=4.460, p<0.01). (2) The K-factor of Loess Plateau showed significant spatial heterogeneity, with higher K-factor in the east and southwest and lower K-factor in the northwest. There were statistical differences in the proportion of medium erodible and medium-high erodible areas among different provinces. (3) Soil physicochemical properties (sand content,silt content, clay content, gravel content, bulk density, pH, cation exchange, basic saturation, exchangeable salt group, carbonate, sulfate, exchangeable sodium salt, electrical conductivity), elevation, slope, and slope direction showed highly significant effect on K-factor (p<0.01). The influence of soil physical and chemical properties on the spatial distribution of K-factor was stronger than those of elevation, slope, and slope direction, and the interaction between factors had more influence on K-factor than individual factors. The study could provide some theoretical basis for the accurate prevention and soil water erosion controlling and soil improvement on the Loess Plateau.

    • LU Ang, TIAN Peng, ZHAO Guangju, MU Xingmin, GENG Ren, ZHANG Shuyu, YANG Lin, ZUO Bate

      2023,37(6):57-64, DOI: 10.13870/j.cnki.stbcxb.2023.06.008

      Abstract:

      In order to better understand the water and sediment transport characteristics in the arid and semi-arid region of the Loess Plateau under complex geomorphological conditions, a distributed watershed water and sediment process model suitable for the Loess Plateau was constructed based on the vertical mixing production mechanism and kinematic wave equation, coupled with watershed soil erosion and sediment transport modules, and the influence of terraces on water and sediment movement was considered. Measured runoff and sediment data of multiple years of flood events in the Xichuan River basin, a tributary of the Yanhe River in Loess Plateau, were used for calibration and validation of the model. The Nash-Sutcliffe efficiency coefficients of runoff simulation were higher than 0.56, with an average value greater than 0.70. The simulated flood peak shape, peak value, and peak time of the simulated floods were in good agreement with the measured floods. However, the model simulation accuracy of soil erosion and sediment transport was relatively low, with a mean Nash-Sutcliffe efficiency coefficient of 0.79 during the calibration period, but only 0.45 during the verification period. The overall trend of the simulation results was consistent with the measured values, but the peak sediment transport simulation values were lower than the measured values. The model can simulate the flood runoff process in watersheds in the Loess Plateau with relatively high accuracy, however the simulated sediment transport values were lower than the measured values, and this was due to both the error propagation of the production convergence flow module and the insufficient consideration of gravity erosion. Therefore, in the future, the model will consider gravity erosion processes such as landslides and rockfalls to improve simulation accuracy and efficiency, providing an effective tool for simulating watershed water and sediment processes and integrated watershed management.

    • XUE Huazhu, JIN Lei, DONG Guotao, ZHANG Haojie, LI Zichuang

      2023,37(6):65-73,82, DOI: 10.13870/j.cnki.stbcxb.2023.06.009

      Abstract:

      In order to explore the law of soil freeze-thaw in Hexi Corridor, based on the hourly surface temperature data of ERA5-LAND, the changes of surface soil freeze-thaw state in the past 40 years were analyzed by dividing different freeze-thaw stages and combining Mann-Kendall trend test and linear regression method. The results showed that: (1) The number of occurrence days in the spring transition period were more in plains than in mountainous areas, and the average annual occurrence days were more than 65 days. The number of occurrence days of complete melting period was more in the north than in the south, more in the east than in the west at the same latitude, and the number of occurrence days in more than 200 days was increasing. The number of average annual occurrence days in the autumn transition period was the least, about 50 days, and the number of days of complete freezing increased with the increase of altitude, among which the spatial distribution of the number of days in the spring transition period changed significantly with time. (2) The start date of the spring transition period and the complete melting period was gradually postponed from north to south, and the maximum difference between the north and the south was more than 90 days, and the spatial distribution of the start date of the complete melting period in different periods changed significantly. The start date of the autumn transition period was the opposite of the former, gradually advancing from north to south, and there was no obvious difference in spatial distribution between different periods. Most areas were completely frozen in December, and high-altitude mountainous areas were fully frozen in November. (3) The start date of the spring transition period was lagging behind in most areas of the study area, and the start date of the complete melting period was advanced, so the number of days of the spring transition period decreased at a rate of 0.2 d/a, while the start date of the autumn transition period in most areas was lagging, resulting in the increase of the number of days of complete melting period at a rate of 0.3 d/a. The number of days of complete freezing period in the northern part of the study area increased, while the southern Qilian Mountains showed a decreasing trend, and the start date of the complete freezing period was generally delayed at a rate of 0.03 d/a. (4) The number of days of complete melting in mountainous areas, oases and desert areas in the past 40 years increased at the rates of 0.393, 0.321 and 0.288 d/a, the start date was advanced by 0.134, 0.188 and 0.206 d/a, the number of days of complete freezing period decreased by 0.353, 0.219, and 0.016 d/a, respectively, and the start date was delayed at the rate of 0.06, 0.1, 0.01 d/a. Under the trend of global warming, for every 1°C increase in annual average temperature, the number of days of complete melting increased by 8.1 days, the start date was advanced by 4.53 days, the number of days of complete freezing period decreased by 9.02 days, and the start date was delayed by 3.27 days. The results can provide a theoretical basis for the study of soil freeze-thaw response to climate change.

    • LIU Zixuan, GAO Yuhao, CHEN Jiazhou, JIANG Ning, WANG Qiuxia

      2023,37(6):74-82, DOI: 10.13870/j.cnki.stbcxb.2023.06.010

      Abstract:

      In order to investigate the reasons for the special variation in the fine furrow morphology of the granitic red soil the rill and to explain how soil configuration influences the development of the rill morphology. we designed three soil configurations (H, S, and HS) with different runoff rates. Three soil configurations, namely, a singlered soil layer (H), single sandy soil layer (S) and upper red and lower sandy laminated soil layer (HS), were designed to simulate indoor fine furrow scouring experiments with different runoff rates (low runoff rate 3 L/min, high runoff rate 6 L/min) and different slopes (medium slope 20°, steep slope 40°). The results showed that: under the H treatment, the gully morphology developed more towards "V" and "U"; under the S treatment, the gully formed a deep and wide trapezoidal cross-section with a narrow top and a wide bottom for a short period of time during the process of the rill development, and then collapsed; under the HS treatment, the gully morphology was able to develop into a trapezoidal section and could continue to expand and develop. Compared with H and S, 21 gully bank failures occurred in the HS steep slope (40°) treatment, of which 63% had single failures of >1 kg. The HS steep slope (40°) treatment had more frequent gully bank failures. The fluctuations of Re and Fr were more drastic than those in the H and S treatments, which is more favourable to the formation of trapezoidal sections.the upper red layer of HS had the lowest water content of 0.31 cm3/cm3 and the highest shear strength of 178 kPa at the time of HS the rill collapse compared to H and S. The lower sand soil layer of HS had a higher water content of 0.33 cm3/cm3 and the lowest shear strength of 54 kPa. The soil configuration of upper red and lower sandy laminated soil layer was the niche the ephemercil gully where the rill morphology of the granitic red soil rill developed into an upper-narrower and lower-deeper and wider trapezoidal profile steep slopes and high runoff volume are more favourable to the formation and development of specific patterns in the rill, and the niche furrows are the initial stage of the development of the Benggang. The results could provide a theoretical basis for the prevention and control of the initial development of the Benggang.

    • ZHANG Zuoyuan, XIA Bin, HAO Wanglin, WANG Ruoyao, XIE Yan, XU Mingxiang

      2023,37(6):83-90, DOI: 10.13870/j.cnki.stbcxb.2023.06.011

      Abstract:

      The purpose of this study is to clarify the pore distribution characteristics of layered soil widely existing in nature. The soil profile of typical dam land in the Loess Plateau was taken as the research object, and the three-dimensional structure of topsoil, plow pan and core soil was analyzed by CT scanning technology. The changes of pore parameters of layered soil with soil structure and the pore characteristics of interface layer were discussed. The results showed that: (1) Slender pores ( pore shape coefficient ≤0.2 ) were the main forms of soil pores in each soil layer. The pore parameters of each soil layer were significantly different. The total porosity of the tillage layer was the highest, and the macropores (≥1 mm) were more distributed. The total number of pores in plow pan was the highest, containing more isolated small pores (≥0.1~0.5 mm) and tiny pores (≥0.06~0.1 mm), but the connectivity was the worst. The pore parameters of the core soil layer were mostly between the upper two layers. (2) The layered soil in the dam section had a certain thickness of the interface layer, and each pore parameter had a sudden change point at the interface of the soil layer, with obvious boundary phenomenon. The pore characteristic parameters showed the law of gradual change of transition position and abrupt change of interface position. In the interface layer, the total soil porosity and connectivity of the plow pan decreased by 41.6% and 69.8%, respectively, compared with the tillage layer. The total soil porosity and connectivity of the interface layer in the subsoil layer were significantly increased by 30.4% and 52.3%, respectively, compared with the plow pan. (3) The size of pores was closely related to the pore shape, with large pore morphology mostly slender and micropore shapes being regular. (4) The deeper the soil layer, the stronger the correlation between connectivity and total porosity, total number of pores, pore size distribution and pore shape. The appearance of interface layer changed the soil pore quality of adjacent soil layer. The artificial action changed the soil pore characteristics of the tillage layer and the plow pan, which was mainly manifested in the disturbance of the tillage layer, which made the plow pan passively pressure-bearing, while the soil layer was less disturbed, and the soil as a whole presented a natural state. The results of this study can enrich the understanding of heterogeneous soil structure and provide a scientific basis for understanding the characteristics of layered soil pores and their possible effects on soil water, air and heat transport at the micro level.

    • LI Boyong, FENG Qingyu, HE Hongbin, CHEN Le, CHEN Liding

      2023,37(6):91-96,103, DOI: 10.13870/j.cnki.stbcxb.2023.06.012

      Abstract:

      Accurate extraction of the current characteristics of check dam is very important for the evaluation of check dam, and the comprehensive characteristic information of check dam can provide an important basis for the reinforcement of diseased and dangerous dam. However, the current check dam feature information extraction still lacks scientific and efficient technology. To address this problem, the proposed method was based on the unmanned aerial vehicle (UAV) tilt photography technology to extract the characteristics of the current status of check dam operation. UAV aerial images were used as the base data to generat a 3D real scene model and a high-precision DEM for the extraction and measurement of important current information such as the number, location, remaining storage capacity, and effective dam height of the check dam. and then analyze the distribution, composition structure, degree of siltation, dam-controlled watershed area and other characteristics of siltation dams in a small watershed. This technology was applied to the small watershed of Shejiagou in Zizhou County, Yulin City, Shaanxi Province, to extract detailed information on the current status characteristics of one large-scale dam and three mediumsized dams. After comparing with the measured data in the field, the relative error of the check dam body information was less than 3.8%. The identified large dams had insufficient remaining capacity and were in a largely silt-filled state, and the crest has obvious subsidence, which has a significant risk of dam failure under extreme precipitation conditions. The proportion of the dam land cultivated area to the small watershed area was only 2.17%, there was still land uncultivated as farmland. The research reaults can provide a new method and idea for dynamic monitoring and scientific management of check dams in small watersheds.

    • WANG Wei, YU Fangqian, LU Fuyun, MA Yuying, CHEN Yang, CHENG Xiaolei

      2023,37(6):97-103, DOI: 10.13870/j.cnki.stbcxb.2023.06.013

      Abstract:

      Based on the heat transfer process in thin water streams, a tracer method was proposed to measure the flow velocity of water streams and a corresponding measurement system was designed. Different test conditions (5°, 10° and 20° slope, 2, 5 and 8 L/min flow rate) were designed on an indoor test slope to investigate the feasibility of the heat tracer measurement of thin water flow velocity and its influencing factors, using the salt tracer method as a control. The results showed that the proposed system measured the transport processes of the thermal tracer accurately and the flow velocities calculated basing on the thermal transport processes had a significant linear relationship with that by the salt tracer. The measured velocities ranged from 0.408 to 1.522 m/s with high accuracy, and the flow velocity by thermal tracer was 1.006 times of the salt tracer with the R2 of 0.993, which indicted the high reliability of the thermal tracing method. As affected by the tracer physical properties, the release mode had a significant effect on the measurement of sheet flow velocities under some hydraulic conditions, and it indicted that the velocities measured by salt and thermal tracer represented velocity of distinct layers of the flow. By using the combined salt-thermal tracer, the average of velocities by thermal and salt tracer can be taken as the velocity of the sheet flow, to improve the representativeness of the measurements under certain hydraulic conditions. The results of the study provided an alternative method for the accurate measurement of sheet flow velocities on slopes with complex underlying surface and high salt content, or under conditions of chemical free. Accurate measurement of thin flow velocities is of great importance for understanding in the field of surface hydrology and soil erosion.

    • PAN Jiapeng, ZHANG Kecun, AN Zhishan, ZHANG Hongxue, XUE Chengjie

      2023,37(6):104-110, DOI: 10.13870/j.cnki.stbcxb.2023.06.014

      Abstract:

      In order to explore the protection benefits of three typical mechanical sand control engineering measures after implementation, through wind tunnel simulation experiments, taking the typical mechanical sand control engineering in Heishanzui area of Dunhuang as a reference, the wind and solid sand resistance benefits of grass grid and nylon grid sand barrier and sand-blocking fence were systematically compared and analyzed. The results show that both grass grid and nylon grid sand barrier can effectively reduce the wind speed, when the indicate wind speed is 20 m/s, the wind reduction rates at 1.5 cm height reach 82.5% and 80.9%, meanwhile, the surface roughness of quicksand is greatly increased, which significantly affects the local wind speed. In addition, these two sand barriers have obvious differences in the ability to waken the wind speed in different heights. The grass grid and nylon grid sand barrier also have significant influence on the local wind-sand flow structure, the sand-fixing ability of grass grid sand barriers is mainly reflected in the near surface. The average sediment transport rate before and after the sand barrier is reduced by 44.2 %, and it has a profound impact on the local flow field structure. Comprehensive analysis shows that the grass grid and nylon grid sand barrier have good windproof and sand-fixing benefits, and the sand-blocking fence has significant sand-blocking benefits. The research results can provide guidance for the construction of local mechanical sand control projects, and provide reference for the layout of sand control projects in other areas.

    • ZHANG Jie, MA Pengfei, WU Suli, LI Shengzhong, LI Min, ZHU Yonghua, XING Yingying

      2023,37(6):111-118, DOI: 10.13870/j.cnki.stbcxb.2023.06.015

      Abstract:

      In order to find out the shallow buried drip irrigation mode of saving water and increasing grain yield of maize, field planting experiments were carried out in Tongliao City, Inner Mongolia in 2021. Based on different irrigation levels of low water (W1=125.4 mm), medium water (W2=153.6 mm) and high water (W3=166.8 mm), as well as 100% water volume of drip irrigation as control (CK=179.8 mm), the characteristics of soil water change under different treatments and their effects on crop water consumption, water use efficiency and plant growth were analyzed. The results showed that the water content of 0-60 cm cultivated soil changed significantly with the increase of irrigation water; With the development of the growth period, the soil water content decreased from jointing stage to filling stage; The water consumption of corn crops is different as a whole, as CK >W3 >W2 >W1; The variation trend of maize growth characteristics was quite different, and W2 treatment had the highest plant height, stem diameter and leaf area index; The overall change of water consumption of maize in each growth period showed a fluctuating trend, reaching the peak in JT growth period; The yield of maize did not increase with the increase of irrigation amount. The yield of maize in W2 treatment was the highest, 5.65% higher than that in CK treatment, and the water use efficiency was the highest, 3.48 kg/m3. Before further optimizing water-saving technology and membrane pollution, W2 treatment of shallow buried drip irrigation may be the appropriate method for farmers. The research results can provide reference for water-saving irrigation of corn in semi-arid areas of China.

    • CHEN Shangmao, GUO Peng, DENG Bo, WEI Leijia, MA Ze, CHEN Dan, BI Lidong

      2023,37(6):119-125, DOI: 10.13870/j.cnki.stbcxb.2023.06.016

      Abstract:

      To investigate the effect of exogenous additions on the characteristics of soil drying and shrinkage crack. Three utilization types of soil samples were selected for paddy field, dry field and forest land and four exogenous additives including quicklime (1 g/kg), fulvic acid (10 g/kg), fish pond sediment (250 g/kg), and biochar (15 g/kg), were added to conduct soil drying and shrinkage tests. The results showed that, in addition to quicklime, the change trend of soil drying shrinkage crack characteristics of different land types under different soil amendment treatments was very consistent, and the surface density, length density and average width of crack showed the change trend of cultivated layer paddy field>dry field>forest land, and plow bottom paddy field>forest land>dry field. Quicklime has no significant effect on soil dry shrinkage crack characteristics; fulvic acid increased the surface density of soil dry shrinkage cracks and the average width, but had no significant effect on the length density of soil dry shrinkage cracks; fish pond sediment increased the surface density of soil cracks and the length density, but had no effect on the average width of dry shrinkage cracks; biochar reduced the surface density of soil cracks and the average width of cracks, but increased the average length density of cracks. Compared with the blank control, the degree of influence of different exogenous additives on the density of soil fracture surface were as follows: Cultivated layer fish pond sediment>biochar>fulvic acid>quicklime, plow bottom fulvic acid>fish pond sediment>biochar>quicklime; the degree of influence on fracture length density was as follows: Cultivated layer biochar >fish pond sediment>quicklime>fulvic acid, plow bottom biochar>fish pond sediment>fulvic acid>quicklime in the plough bottom layer. Exogenous additives have an important effect on the characteristics of soil cracks. Quicklime has no significant effect on the development of soil cracks. Fulvic acid and fish pond sediment can promote the development of soil cracks, and biochar can inhibit the development of soil cracks. The results can be used to improve the physical and chemical properties of soil using improved soil agents in agricultural production.

    • ZHAO Yibo, YU Yang, SUN Baoping

      2023,37(6):126-133,144, DOI: 10.13870/j.cnki.stbcxb.2023.06.017

      Abstract:

      To understand the match between supply and demand of ecosystem services, the spatial and temporal trends of supply and demand and their influencing factors. Using water production services in Shanxi Province as an entry point, and based on physical geography and social statistical data for 1990, 2000, 2010, and 2020, used geostatistical analysis and InVEST model to analyze the spatio-temporal changes characteristics of supply and demand. The results showed that: (1) In terms of the spatiotemporal patterns supply and demand for water production services in Shanxi Province showed an increasing trend over the 30-year period. The southeast region of Shanxi (Jinzhong, Changzhi and Jincheng cities) was the main supply area for water production services, while the areas with high demand for water production services were mainly the urban areas of Taiyuan, Datong, Changzhi and Yangquan. (2) In terms of matching the supply and demand of water production services, the area of regions undersupplied with water production services increased sharply from 1.82% to 16.80% in 1990 to 2000, while it decreased sharply from 16.95% to 5.34% in 2010 to 2020, with the spatial matching of supply and demand improving. (3) Through spatial autocorrelation analysis, there was an obvious spatial mismatch between the supply and demand of water production services in Shanxi Province. The research results provide theoretical support for comprehensively sorting out the supply and demand characteristics of ecosystem services in Shanxi Province.

    • YIN Haojie, WANG Rongrong, JIANG Guiying, CHE Ziqiang, CHEN Tianpeng, HU Jiajie, GUO Rougu, PANG Tiantian, LEI Qiqi

      2023,37(6):134-144, DOI: 10.13870/j.cnki.stbcxb.2023.06.018

      Abstract:

      In order to explore the effects of soil drought at different growth stages on photosynthetic physiological characteristics and yield of different drought resistant wheat varieties. Taking "Xinchun 22 (XC22)" with weak drought resistance variety and "Xinchun 6'(XC6)" with strong drought resistance variety as the materials, under soil column cultivation and field conditions, five treatments were set up: conventional irrigation (CK), mild drought at tillering stage (W1), moderate drought at tillering stage (W2), mild drought at jointing stage (M1) and moderate drought at jointing stage (M2), respectively. The changes of leaf chlorophyll content, leaf area index (LAI), gas exchange parameters, chlorophyll fluorescence parameters, above-ground dry matter accumulation, panicle weight and yield of wheat were studied. The results showed that the drought-resistant variety "XC22" was more affected by water stress and its recovery ability was weaker after rewatering. Only W1 treatment could recover to the level of stalemate with CK. Compared with "XC22", the "compensation effect" of strong drought resistant variety "XC6" was more obvious after M1 treatment. The RuBPC enzyme activity, gas exchange parameters and chlorophyll fluorescence parameters could quickly recover to CK level after rehydration, which was stronger than other treatments. At milk stage, the net photosynthetic rate (Pn), stomatal conductance (Gs), transpiration rate (Tr) and maximum fluorescence yield under dark adaptation (Fm), maximum fluorescence yield under light adaptation (Fm'), actual photosynthetic quantum yield (ΦPSⅡ) and photochemical quenching coefficient (qp) of PSⅡ were significantly increased by 11.39%, 7.50%, 7.38% and 7.86%, 6.78%, 17.24%, 2.48%, respectively, compared with CK. Mild drought treatment did not reduce dry matter accumulation and yield of wheat, but contributed to the increase of ear weight, and the dry matter accumulation, ear weight and yield of "XC6" under M1 treatment were significantly higher than CK. The correlation and path analysis between photosynthetic parameters and yield showed that yield was significantly positively correlated with Pn, Gs, Fm, Fm' and qp, Pn was the most important promoting factor in yield formation. The recovery and maintenance of photosynthetic physiological characteristics of spring wheat after anthesis were more strongly affected by water stress at jointing stage. Under the drip irrigation model in Xinjiang, mild drought stress at the early growth stage was beneficial to improve the photosynthetic performance of drought-resistant wheat varieties after rewatering, increase the accumulation of aboveground dry matter, promote the transport of photosynthate to reproductive organs, and facilitate the formation of yield.

    • Lü Hao, WANG Xing, SONG Naiping, CHEN Juan, ZHANG Yifei, WU Xudong, YU Dian, YANG Xinguo, WANG Lei, CHEN Lin

      2023,37(6):145-152, DOI: 10.13870/j.cnki.stbcxb.2023.06.019

      Abstract:

      To clarify the response of soil moisture to extreme drought precipitation in typical plant communities in the desert steppe. In this study, the soil water content of four typical plant communities (Agropyron mongolicum, Sophora alopecuroides, Stipa breviflora, and Achnatherum splendens) in this region is studied. The 0—120 cm soil water content of these communities was monitored from 2020 to 2021, respectively, to analyze the dynamic characteristics of soil water content and its response to precipitation during the consumption, recovery, and stabilization periods. The results showed that during the soil water consumption period, the soil water maintained a deficit state of 4.56%~7.87%, and this state extended from 0—40 cm shallow soil layers to 80—120 cm deep soil layers with the continuous drought. During the soil moisture recovery period, the concentrated Ⅴ grade precipitation (single >20 mm) could restore the soil moisture in the depth of 80—120 cm, and the soil moisture was mainly recovered in the shallow layers of 0—40 cm with the continuous drought. During the soil moisture stabilization period, the soil water content in each layer of the four plant communities was >10% as the drought continued. By comprehensive comparison of the four plant communities, the soil water content of Stipa breviflora community was relatively high in each period, and the soil water recovery of this community was synchronized in the shallow layers and deep layers, which has important reference value for vegetation restoration and conservation in the water-restricted areas.

    • LUO Pizhao, WANG Yunqi, LI Tong, QI Zihan, HE Xiangchang, LI Kewen

      2023,37(6):153-160, DOI: 10.13870/j.cnki.stbcxb.2023.06.020

      Abstract:

      In order to study the variation of strength characteristics with moisture content of natural slopes. The influence of moisture content on soil failure, shear strength and initial tangent modulus was carried out by designing reconstituted soil with different volume moisture content (20%, 27%, 35%, 40%, 45%) and two root content (RAR=0.1%, 0.3%). The results showed that: (1) The specimen rupture mode was mostly shear deformation and shear expansion deformation, and when the moisture content was 20% and 27%, the obvious shear penetration surface fracture zone appeared, and the rest of the moisture content was shear deformation. (2) The effect of moisture content on the shear strength of the root soil complex was mainly reflected in the cohesion, and when the moisture content increased from 20% to 45%, the cohesion of the two kinds of root-soil complex decreased by 67% and 72%; when the moisture content was lower than 35%, it could be expressed by logarithmic relationship, and the cohesion decreased significantly with the increase of moisture content; when the moisture content reached more than 35%, it could be expressed by linear relationship, and the decline rate of cohesion slowed down; the shear strength increased with the increase of root content. (3) The relationship between the initial tangential modulus and the moisture content of the root-soil complex under different root content and confining pressure could be fitted by linear relationship, and when the moisture content increased from 20% to 45%, the initial tangential modulus of the two root-soil complex with root content decreased by 43% and 47% on average. Comprehensively considering the influence of elastic-plasticity and plant factors on soil displacement or deformation, the accuracy of slope stability calculation could be improved. The research results can provide scientific reference for the management of plant slope and soil and water conservation vegetation construction, and enrich the scientific theory in the field of root soil consolidation.

    • WAN Zhigang, DING Wenguang, PU Xiaoting, WU Yansong, WANG Yiyue

      2023,37(6):161-169, DOI: 10.13870/j.cnki.stbcxb.2023.06.021

      Abstract:

      To accurately characterize the spatial and temporal heterogeneity of water yield in Qilian Mountains National Park and explore the influencing factors and driving mechanisms affecting water yield. The InVEST model was used to visualise the spatial and temporal pattern of water yield in the Qilian Mountains National Park from 1990 to 2018 based on the parameters of precipitation, evapotranspiration of reference crops, soil depth, root depth, and land use type, using a geo-detector and combined with a scenario simulation methods to assess and quantify the effects of climate, land use, vegetation, terrain, and other factors on the spatial heterogeneity and changes in water yield in the Qilian Mountains National Park. The results showed that: (1) From 1990 to 2018, the water yield in the study area increased significantly with a trend of 0.56×108 m3/a, with a spatial increasing trend from west to east. (2) Farmland and Forestland had the largest water yield depth, and Unused land and Grassland were the main contributors to water yield in the study area. The high-value water yield depth areas were located at high altitudes between 3 200 m to 4 600 m. (3) Precipitation was the first driver of spatial heterogeneity of water yield, and the interaction with actual evapotranspiration and land use type dominates. (4) From 1990 to 2018, climate change was the main driver of changes in water yield, with a positive effect on total water yield, followed by land use change, which mainly affects the spatial distribution of water yield change but had little effect on total water yield. The research results can further provide the basic theoretical for the water resources management and sustainable development of Qilian Mountain National Park.

    • YANG Shuya, SHI Haibin, MIAO Qingfeng, LIU Wei, ZHAO Yi, YAN Yan, BIAN Liqiang, ZHAO Wei

      2023,37(6):170-179, DOI: 10.13870/j.cnki.stbcxb.2023.06.022

      Abstract:

      In order to explore the evolution law of groundwater environment before and after the deep water-saving reconstruction in ShenWu Irrigation District, aiming at the groundwater depth, salinity and their relationship, the spatial and temporal changes of groundwater depth and salinity were analyzed by using the method of regional well distribution, positioning and long-term monitoring, and the classical geostatistics theory. The results showed that: (1) After the deep water-saving reconstruction, the groundwater depth in Shen-Wu-irrigated area showed an increasing trend, and the average groundwater depth increased from 1.83 m before the water-saving reconstruction to 3.36 m after the water-saving reconstruction, with an increase rate of 83.9%. The buried depth in the center and south of the irrigation area is larger, and a funnel is generated locally. The maximum buried depth increases to 9.37 m, while the buried depth in the north of the irrigation area changes below 0.6 m. (2) The implementation of the water-saving reconstruction project significantly increased the salinity of groundwater, from 1 296 mg/L before the water-saving reconstruction to 2 634 mg/L after the water-saving reconstruction, an increase of 103.47%. The salinity of groundwater in ShenWu Irrigation District is higher in the southeast and northwest, but lower in the central area. With the implementation of the water-saving reconstruction project, the area of fresh water is gradually reduced, while the area of brackish water is gradually increased. (3) There is an exponential relationship between groundwater depth and salinity in the study area. Groundwater salinity decreases with the increase of groundwater depth, and the coefficient of determination of the two is 0.170 8. From the perspective of space, the area with small groundwater depth corresponds to the high salinity of groundwater, and the area with large groundwater depth corresponds to the low salinity of groundwater, so as to find out the change law of groundwater level and water quality in the irrigation area, so as to provide scientific basis for soil salinization prevention and control.

    • ZHONG Jianjun, LI Lin, WEI Shiguang, SHEN Kaihui, ZHOU Jinggang, WEN Zhifeng, ZHAO Yi, YANG Xintian

      2023,37(6):180-186,193, DOI: 10.13870/j.cnki.stbcxb.2023.06.023

      Abstract:

      In order to explore the distribution of soil carbon, nitrogen and phosphorus storage in Karst forest in the Lijiang River Basin, and to provide a theoretical basis for protecting the fragile Karst ecosystem in the Lijiang River Basin, a total of 15 natural forest quadrats of 20 m × 20 m were set up in the typical Karst forests in the upper, middle and lower reaches of the Lijiang River, and the forest vegetation was surveyed for each tree. The 0-20, 20-40 cm soil layers were collected by five-point collection method to analyze the spatial distribution of soil carbon, nitrogen and phosphorus storage and driving factors, and to quantify the contribution of various biological and abiotic factors to the formation of soil nutrient storage pattern in karst forest. The results showed that: (1) The average distribution of soil carbon, nitrogen and phosphorus storage in the Karst forest in the Lijiang River Basin was upstream > downstream > midstream. In the Karst forest soil of the Lijiang River Basin, the storage of carbon, nitrogen and phosphorus was 55.8~192.0, 3.1~14.8, and 6.0~12.0 kg/m2, respectively. The storage of carbon and nitrogen in 20 cm soil layer in the same watershed was significantly higher than that in 20-40 cm soil layer, while phosphorus storage did not show significant difference in the soil layers of different depth in the Lijiang River Basin. (2) Carbon storage showed a significant positive correlation with C/P, N/P, Shannon-Wiener index and Simpson index of forest species diversity; nitrogen storage had a significant positive correlation with C/P, N/P, Shannon Wiener index and Simpson index, while a significant negative correlation with C/N; the phosphorus storage had a significant negative correlation with C/N, and there was no significant correlation with forest species diversity. (3) The stoichiometric characteristics of Karst forest soil chemistry in the Lijiang River Basin were the direct driving factors driving the distribution of soil carbon, nitrogen and phosphorus storages, and the stoichiometric characteristics of deep soil were the most important direct driving factors. Secondly, forest species diversity played an important role in the immobilization and input of soil nutrients, directly affecting and driving the formation of soil carbon and nitrogen storage distribution pattern. The formation of phosphorus storage was not driven by the impact of forest vegetation conditions. In the Karst forest soil in the Lijiang River basin, the stoichiometric characteristics and the diversity of forest plants had played an important role in the formation and decomposition of soil carbon, nitrogen and phosphorus reserves. It is advocated to improve the water and fertilizer storage functions of forest soil in the Lijiang River Basin by improving the species diversity of forest vegetation in the Lijiang River Basin, while protecting the fragile karst forest ecosystem in the Lijiang River Basin.

    • JIANG Yaoyu, WANG Bin, CHEN Zuming, WANG Wengang

      2023,37(6):187-193, DOI: 10.13870/j.cnki.stbcxb.2023.06.024

      Abstract:

      To quantitatively analyze the coupling characteristics of water and heat in the profile of typical black soil cultivated land during the freezing process, the topsoil in the typical black soil region in NE China was taken as the research object. Through indoor single soil column simulation experiments and combination with COMSOL Multiphysics model PDE module, the coupling solution of temperature field and moisture field during black soil freezing process was achieved. Results showed that: (1) The COMSOL model could realize the hydrothermal coupling analysis of the freezing process of black soil profile, and the fitting effect of temperature field (R2=0.83, RMSE=0.91 ℃) and water field (R2=0.88, RMSE=0.02 cm/cm3) was good, which could meet the fitting accuracy requirements. (2) The temperature change rate of black soil cultivated land profile exhibited a trend of rapid cooling followed by a slow approach to stability, and the closer to the cold end, the faster the rate at which soil temperature decreased to the stability stage. (3) The frozen black soil cultivated land profile underwent significant water redistribution during the freezing process. An ice crystal aggregation phenomenon was observed at the warm end, which occured at a fast rate, while the cold end showed the opposite phenomenon [0.000 34~0.000 42 cm/(cm3·h)]. The research results can provide technical support for analyzing the water heat transport law of frozen black soil, as well as a theoretical basis for the study of the mechanism of frozen thawing and hydraulic composite erosion of black soil profiles and dynamic simulation of water-heat in profiles.

    • QI Mi, WANG Fei, HUA Yongchun, WANG Mingyuan

      2023,37(6):194-200, DOI: 10.13870/j.cnki.stbcxb.2023.06.025

      Abstract:

      In order to achieve the "Dual carbon" target of the Inner Mongolia Autonomous Region, based on the land use data (LULC) in 2000, 2010 and 2020 and followed the 14th Five-Year Plan of Inner Mongolia Autonomous Region, three scenarios of natural development, cultivated land protection and ecological protection were established. The PLUS model was used to forecast and analyze the spatial distribution of land use in 2030 of Inner Mongolia Autonomous Region. The changes of carbon storage under different development scenarios in the Region were analyzed with the InVEST Model. The research results showed that: (1) The area of forest land and construction land in Inner Mongolia increased from 2000 to 2020, while the area of cultivated land, water area, grassland and unused land showed a downward trend, and the main transfer direction was from cultivated land to construction land. (2) Under the state of natural development, the area of cultivated land, grassland, water area, and unused land decreased, while the area of forest land and construction land showed an upward trend; under the state of ecological protection, the area of forest land, grassland, and water area increased compared with the natural development scenario; under the cultivated land protection scenario, the cultivated land area showed an expansion trend compared with the natural development scenario, and the expanded area reached 4.69×104 hm2. (3) In 2000, 2010, and 2020, the carbon storage in Inner Mongolia reached 1.371 7×1010, 1.370 9×1010 and 1.370 6×1010 t, respectively, showing a decreasing trend year by year. In 2030, the total carbon storage under the three scenarios of natural development, cultivated land protection and ecological protection was 1.370 1×1010, 1.370 6×1010 and 1.371 9×1010 t, respectively. Compared with the natural development scenario, the carbon storage of cultivated land protection and ecological protection was larger, indicating that the implementation of protection measures could effectively control the decline of carbon storage. Therefore, the implementation of cultivated land protection and ecological protection policies could control the expansion of cultivated land into construction land and unused land, and improve the land use structure, and help to delay the loss of regional carbon storage.

    • GE Maoquan, WANG Chun, XU Hongda, YANG Fajun, WU Ziwei, LIN Shaoying, ZHANG Yongxun, LI Xiande, WANG Weiqi

      2023,37(6):201-208, DOI: 10.13870/j.cnki.stbcxb.2023.06.026

      Abstract:

      The soil of tea garden in Bailin Town (BL), Diantou Town (DT), Panxi Town (PX), Guanyang Town (GY) and Taimushan Town (TMS) in Fuding City, Fujian Province were taken as the research object. The composition and stability of aggregates, organic carbon content, carbon sequestration contribution rate and infrared spectrum of organic carbon of each particle size aggregates were studied to reveal the distribution and molecular structure characteristics of soil organic carbon in tea garden soil from the aggregate scale. The results showed that: (1) The composition of soil aggregates differed among sampling sites, but with the deepening of soil layer, the content of macroaggregates (0.25~2 mm) and microaggregates (0.053~0.25 mm) decreased, while the content of silt-clay aggregates (<0.053 mm) increased in all sampling sites. (2) Decreased in mean weight diameter (MWD) and geometric mean diameter (GMD) and increased in fractal dimension (D) of all sampled sites with deepening of the soil layer and decreased in structural stability of the agglomerates. (3) The organic carbon content of the aggregates decreased with the deepening of the soil layer, and the contribution rate of carbon sequestration of aggregates was mainly controlled by the percentage of aggregates, and the contribution rate of carbon sequestration of macroaggregates was relatively larger. (4) The organic carbon of each size aggregates was mainly derived from polysaccharide carbon or aliphatic carbon. The silt-clay aggregates in 0—15 cm soil layer had more stable carbon than those in macroaggregates and microaggregates. The aggregates in the 15—30 cm soil layer had more stable carbon than the corresponding size aggregates in the 0—15 cm soil layer. The research results can provide theoretical reference for the scientific management of tea garden soil organic carbon.

    • YANG Fajun, WANG Weiqi, WU Ziwei, XU Hongda, GE Maoquan, LIN Shaoying, LI Xiande, ZHNAG Yongxun, WU Chuanhui

      2023,37(6):209-218, DOI: 10.13870/j.cnki.stbcxb.2023.06.027

      Abstract:

      In order to study the effects of soil carbon(C), nitrogen (N), phosphorus (P), potassium (K) content and their eco stoichiometric ratio on soil microbial community structure, soil nutrient-to-metrological ratio and its influence on the characteristics of bacterial communities were systematically measured and analyzed by taking tea gardens in Fuding City, Fujian Province as the research object. The results showed that: (1) The mean contents of C, N, P and K in tea garden soil were 18.39, 1.96, 0.91, 15.57 g/kg, and the mean values of soil C∶N, C∶P, C∶K, N∶P, N∶K, N∶K, were 9.24, 61, 1.24, 3.32, 0.13 and 22.39, respectively. (2) The dominant bacteria in the soil were Paludibaculum, Mycobacterium, and Acidobacteria; the dominant bacteria genera were Paludibaculum, Mycobacterium and Bradyrhizobium, and the composition and structure of bacterial communities in different tea plantations were similar, but the bacterial diversity index was significantly different (p<0.05). (3) The correlation analysis results of soil bacteria and nutrient and their measurement ratio in tea gardens at the genus level showed that K was significantly positively correlated with Thermodesulfovibrio and Gaiella (p<0.01), P was positively correlated with Clostridium, Rhodanobacter, and Geobacter (p<0.001), while N was significantly negatively correlated with Pseudomonas (p<0.01), K was significantly negatively correlated with Kitasatospora and Phenylobacterium (p<0.01). Soil C∶N, C∶P, N∶P, P∶K were significantly positively correlated with Chthoniobacter, Dictyobacter, Paraburkholderia, and Bacillus (p<0.05), and were negatively correlated with Bradyrhizobium, Vicinamibacter, Gaiella, and Pseudomonas (p<0.001). (4) The functional prediction results showed that most of the predicted functions of tea garden bacteria were mainly metabolic activities, which had a positive effect on soil nutrient cycling in tea gardens and improving soil carbon sequestration efficiency through metabolic activities. Therefore, this study is of great significance for the study of soil microbial diversity in tea gardens based on nutrient management.

    • FENG Guoping, TIAN Guohang

      2023,37(6):219-227, DOI: 10.13870/j.cnki.stbcxb.2023.06.028

      Abstract:

      Land cover change is a significant factor contributing to the variation in carbon sources and sinks in terrestrial ecosystem. Investigating the relationship between land use transition and carbon dynamics is crucial for optimizing regional land use planning and achieving sustainable development and the "dual carbon" goals. This study employed spatial analysis technology to analyze the temporal and spatial changes of carbon sources and sinks. By considering three future development scenarios, it predicted the future dynamics of carbon sources and sinks in Zhumadian City. The results showed that: (1) The net carbon emission of Zhumadian City had exhibited an increasing trend, rising from 268.13×104 t in 2005 to 578.04×104 t in 2020, with an increment of 309.91×104 t. (2) Land use transitions in Zhumadian City involved a reduction in carbon stocks primarily due to the conversion of cropland to construction land and forestland to cropland, while the increase in carbon stocks primarily stemmed from the conversion of cropland to forestland and construction land to water area. (3) Applying the grey model and PLUS model, future spatiotemporal changes in land use and carbon dynamics in Zhumadian City were projected. The results indicated a continuous rise in net carbon emissions, although the rate of increase significantly slowed down under the scenario of cultivated land protection. Based on the preservation of cultivated land, Zhumadian City should restrain the expansion of construction land into ecological areas, expedite agricultural technological reforms, and foster low-carbon circular development.

    • CHEN Lei, ZHANG Zhuodong, LI Yetong

      2023,37(6):228-237, DOI: 10.13870/j.cnki.stbcxb.2023.06.029

      Abstract:

      In order to investigate the effect of rock outcrops on soil physicochemical properties, four rock outcrops and one control group were used to analyse the spatial variability of soil physicochemical properties. The results showed that: (1) In the sloping cropland with rock outcropping, the variation range of soil bulk density, clay, silt, and sand was 0.87~1.42 g/cm3, 25.70%~41.80%, 38.11%~51.60% and 13.76%~27.54%, respectively. The spatial variation of soil bulk density, clay and silt was weak and higher spatial variability than that of the control. The spatial variability of sand grains was moderate and lower than that of the control. (2) The spatial variability of soil total carbon, total nitrogen, total phosphorus and total potassium ranged from 9.82 to 23.13, 0.94 to 2.15, 0.65 to 2.93 and 7.38 to 20.35 g/kg, respectively, while the spatial variability of soil effective phosphorus and fast-acting potassium ranged from 1.44 to 2.63 and 7.35 to 106.02 mg/kg, respectively, all with medium and higher spatial variability than the control group. (3) Soil bulk density, clay and silt were negatively correlated with other soil physicochemical properties, and the correlation was more significant in the sloping cropland with rock outcropping than that of the control group. There was a significant negative correlation between sand and clay, and a positive correlation between sand and other soil chemical properties. (4) The number, gradient, ratio, and height of rock outcropping had a complex impact on soil physical and chemical properties. The spatial variation of soil physicochemical properties varied with the characteristics of different rock outcropping. The research results contribute to a deeper understanding of the impact of rock outcropping on the erosion process and mechanism on karst slope, and provide scientific reference for soil erosion and soil conservation work.

    • ZHAO Na, LI Ruidong, WANG Xiaoli, DUAN Jianjun, ZHENG Qinwen, LI Mingrui

      2023,37(6):238-245, DOI: 10.13870/j.cnki.stbcxb.2023.06.030

      Abstract:

      In order to explore the effects of adding calcium carbonate on active organic carbon components and microbial community composition under different temperature conditions, the typical yellow soil in Guizhou province was taken as the research object, and six treatments were set up (the treatments with and without adding calcium carbonate at culture temperatures of 15, 25, 35 ℃) by isotope labeling method. By analyzing the effects of calcium carbonate addition on soil active organic carbon and microbial community composition at different temperatures, the distribution rule of foreign carbon in soil active carbon pool was revealed, with a view to providing a theoretical basis for organic carbon sequestration and improvement of typical yellow soil in Guizhou. The results showed that: The addition of calcium carbonate significantly increased the contents of DOC and MBC in soil at different temperatures (p<0.01), and the contents of DOC in soil treated with calcium carbonate reached the maximum value on the 5th day of culture. Compared with the treatment without calcium carbonate, the soil DOC content in the treatment with calcium carbonate were significantly increased by 83.41%, 80.37% and 90.41% at 15, 25 and 35 ℃, respectively. The temperature of calcium carbonate addition had significant effects on soil DOC and MBC (p<0.05). On the 15th and 60th day of culture, the contents of DOC and MBC in soil showed significant differences at different temperatures, and the overall content of DOC in soil was 35 ℃>15 ℃>25 ℃, and the overall content of MBC was 15 ℃>25 ℃>35 ℃. Isotopic labeling showed that the contents of 13C-DOC and 13C-MBC peaked at 15, 25 and 35 ℃ on the 1st and 5th day of culture, and the contribution rate of 13C-DOC to the total soil DOC was 16.85%, 21.20% and 15.22%, respectively. The contribution rate of 13C-MBC to total soil MBC was 11.95%, 10.49% and 17.18%, respectively. The addition of calcium carbonate significantly increased soil pH. High-throughput sequencing showed that the input of exogenous calcium carbonate had significant effects on the relative abundance and community structure of bacterial community composition, but had little effect on fungal community composition at day 60 of culture. The addition of calcium carbonate increased the relative abundance of Proteobacteria and decreased the relative abundance of Chlorocurvula. Correlation analysis showed that soil pH was positively correlated with the dominant bacteria Proteobacteria and Basidiomycota, and negatively correlated with Chloroflexi and Ascomycota. The chloromycetes was significantly negatively correlated with soil DOC, while the actinomycetes was significantly positively correlated with soil MBC, 13C-DOC and basidiomycetes was significantly positively correlated with DOC, 13C-MBC and 13C-DOC. In conclusion, the effect of exogenous calcium carbonate on soil active organic carbon was greater than that of temperature. Exogenous calcium carbonate increased soil pH, soil DOC and MBC contents, and changed the composition and abundance of soil microbial community. Therefore, calcium carbonate addition is an effective measure for sequestration and improvement of organic carbon in yellow soil.

    • YU Wenfei, WANG Peipei, LIU Jun'e, ZHOU Zhengchao, YOU Ben

      2023,37(6):246-254, DOI: 10.13870/j.cnki.stbcxb.2023.06.031

      Abstract:

      In order to investigate the changes of organic carbon content fractions in aggregates of different particle sizes under the effects of vegetation roots and their main influencing factors, two typical vegetation species (Artemisia gmelinii Web. and Stipa bungeana Trin.) growing naturally on the Loess Plateau were were chosen as subjects, while abandoned land for one year served as control (CK). The mass ratio of each particle size aggregates and their soil organic carbon (SOC), particulate organic carbon (POC) and mineral associated organic carbon (MAOC) contents were determined and the relationships between the basic properties of the soil, the characteristics of the root system and the carbon fractions of each different particle size aggregates were analyzed. The results revealed the following findings: (1) Compared to CK, contents of POC and MAOC were significantly higher in Artemisia gmelinii Web. and Stipa bungeana Trin, with POC contents varying more than MAOC. The experimental land of Artemisia gmelinii Web. and Stipa bungeana Trin. significantly increased the carbon fraction contents of macro-aggregates (>0.25 mm) by 7.44~8.26 times and 3.76~4.37 times respectively, which had the bigger increase than that of the micro-aggregates. (2) The organic carbon content of large macro-aggregates was significantly correlated with POC and MAOC, that of small macro-aggregates was significantly correlated with POC, and that of micro-aggregates was significantly correlated with MAOC. The inclusive effects of POC and the binding effects of MAOC by the aggregates coexisted, and both of them acted in different ways to influence the changes of organic carbon in aggregates, and then affected the total organic carbon of the soil, of which the organic carbon content of small aggregates was the most important influencing factor. (3) Soil aggregate carbon fractions were significantly correlated with vegetation root parameters, where root surface area density (RSAD) and root weight density (RWD) played major roles in influencing the aggregate carbon fractions, explaining variance of 50.5% and 17.0% respectively. Through the effects of carbon fractions on organic carbon in soil aggregates of all particle sizes, plant roots can effectively enhance soil organic carbon contents and improve soil quality, and the results of this study provide a reference for soil carbon sequestration and vegetation restoration in the Loess Plateau region.

    • LI Dandan, PENG Yi, FENG Gu, ZHANG Lin

      2023,37(6):255-261, DOI: 10.13870/j.cnki.stbcxb.2023.06.032

      Abstract:

      In order to improve the safe and sustainable utilization of phosphorus in high-fertility soil, and explore the C∶P ratio of high-fertility soil. Soil of three typical crop types (grain crop-maize, local characteristic high value economic crop-tobacco and vegetables with high value and high nutrient input) from 27 sample sites in Erhai Lake Basin were selected to analyze the characteristics of soil carbon and phosphorus content and C∶P ratio. The results showed that: (1) The soil organic carbon (SOC) content was 31.91 g/kg, and there were no significant difference in SOC content among the different crop types. (2) The contents of available inorganic phosphorus (NaHCO3 extracted inorganic phosphorus, NaHCO3-Pi) and available organic phosphorus (NaHCO3 extracted organic phosphorus, NaHCO3-Po) were 156.7 mg/kg and 63.43 mg/kg, respectively. There were no significant difference in the contents of available inorganic and organic phosphorus (NaHCO3-Pi/NaHCO3-Po) among the different crop types, and the results were as follows: vegetable field > tobacco field > maiza field. (3) The C∶NaHCO3-Pi ratio and C∶NaHCO3-Po ratio of farmland soil in Erhai Lake Basin were 321.42 and 1138.25, respectively. The C∶NaHCO3-Pi ratio of farmland soil in Erhai Lake Basin was significantly lower than the China and the southwest China. The C∶NaHCO3-Pi ratio of vegetable field was significantly lower than that of maize field. Our results showed that the soil carbon and phosphorus content in Erhai Lake Basin was high, especially the high phosphorus content, leading to a significant decrease in soil C∶P ratio. The C∶P ratio of high input vegetable land was significantly lower than that of maize field, which not only impacted the transformation of phosphorus by soil microorganisms, but also brought about phosphorus pollution. Therefore, the safe and sustainable utilization of phosphorus in high fertility soil can be achieved by regulating the C∶P ratio. Adding materials with high C∶P ratio, such as crop straw, can increase the soil C∶P ratio, increase the immobilization of soil phosphorus by microbes, and store soil phosphorus in microbial phosphorus pool, which can reduce the loss of soil phosphorus to water.

    • DENG Milin, YE Guiping, XU Chao, WAN Song, HE Jizheng, LIN Yongxin

      2023,37(6):262-267, DOI: 10.13870/j.cnki.stbcxb.2023.06.033

      Abstract:

      To reveal the response of soil N2O emissions to forest types and nitrogen addition in subtropical forests, soil samples were collected from Castanopsis carlesii secondary forests, Cunninghamia lanceolata plantation and Pinus massoniana plantation located in Sanming City, Fujian Province. A microcosm was carried out and the soils were amended with NH4NO3 at four levels: no nitrogen addition (N0 mg/kg), low nitrogen addition (N10 mg/kg), medium nitrogen addition (N25 mg/kg) and high nitrogen addition (N50 mg/kg) to determine N2O flux. The results showed that nitrogen addition generally decreased soil pH, while increased soil NH4+-N and NO3--N contents. The cumulative N2O emissions in C. lanceolata and P. Massoniana plantations with no nitrogen addition were 9.67 and 9.62 mg/kg, respectively, and were significantly higher than 6.81mg/kg in C. carlesii secondary forest. Similar trend was found in soils with low nitrogen addition. However, in the medium and high nitrogen addition treatments, there were no significant differences in cumulative N2O emissions among the three forest stand types. Nitrogen addition increased soil N2O emission in all the three forest types, with the effect size of low nitrogen addition on N2O emissions in secondary forest soil being 0.01, significantly lower than the effect size of 0.45 in C. lanceolata and P. massoniana plantation soils. Conversely, the effect sizes of medium and high nitrogen additions on N2O emission were significantly higher in secondary forests than plantations. These results indicated that N2O emissions in secondary forests was more likely to be stimulated by medium or high nitrogen addition. Cumulative N2O emissions were positively associated with soil NH4+-N and NO3--N contents (p<0.01), rather than soil pH, indicating that available nitrogen was the main factor controlling soil N2O emissions in forest soils under nitrogen additions. Taken together, N2O emissions were higher in plantation soils than in secondary forest soil, but N2O emissions in secondary forests soil were more sensitive to medium and high nitrogen additions.

    • SONG Shujun, CUI Xiaoru, CHEN Qixian, CHEN Xiong, YANG Rong

      2023,37(6):268-275, DOI: 10.13870/j.cnki.stbcxb.2023.06.034

      Abstract:

      The responses of soil trace elements to green manure fallow were investigated to provide reference for soil nutrient management and agricultural production in the large region of farmland. Based on the three-year multi-point monitoring data in the dryland farming area of central Gansu, six indexes of soil trace elements, including available Fe, available Mn, available Cu, available Zn, available Mo, and available B, were selected to compare and analyze the differences of soil trace elements before and after fallow planting of green manure. The results showed that: (1) Compared with the basic soil, after three years of fallow, the contents of available Mn, available Cu, and available Zn in soil were significantly increased by 18.8%, 22.5%, 14.3%, respectively (p<0.05). The contents of available Fe and available B showed significant decreasing trends (p<0.05), while available Mo did not change significantly. (2) Regression analysis showed that the magnitude of variation of available Fe, available Mn and available Cu were all negatively linearly related to the basal content of trace elements before fallow, while effective Zn and effective Mo were all negatively logarithmic (p<0.05), and had a significant enhancement effect on agricultural soils with basal content of available Mn, available Cu, available Zn, and available Mo of less than 8.0, 0.9, 0.3, 0.06 mg/kg, respectively. There were significant negative linear correlations (p<0.05) between the magnitude of changes in available Fe, Mn, Cu and the pre-fallow basic nutrient contents of soil organic matter and total nitrogen. (3) Further correlation analysis of trace elements and macronutrients in the soil after fallowing showed that available Fe, Mn, and Zn were significantly positively correlated with soil organic matter, total nitrogen, available phosphorus and available potassium. Except for available Mo, the other five trace elements were significantly negatively correlated with soil pH. In conclusion, the implementation of fallow mode of green manure planting can improve the contents of available Mn, Cu, and Zn in the dryland farming area of central Gansu to some extent, particularly good for soils of Mn-deficient, and it is more effective for soils with low basic soil nutrient content and alkaline soils.

    • GAO Haocheng, MU Ren, JIAO Ting, CHEN Xin, MA Shumin, ZHANG Xia

      2023,37(6):276-282, DOI: 10.13870/j.cnki.stbcxb.2023.06.035

      Abstract:

      In order to investigate the effects of different nitrogen addition levels on soil physicochemical properties and available nutrients of drooping paniculus calcareous grassland under alpine ecological condition, the experiment of nitrogen addition was carried out in the 2nd age paniculus calcareous artificial grassland at Tianzhu Alpine Grassland Experimental station. A single factor experimental design was used to determine the nitrogen addition dose in the experiment site according to the nitrogen deposition distribution pattern in China, and five nitrogen addition levels of control N0 (no nitrogen), N1 (12 kg/hm2), N2 (24 kg/hm2), N3 (48 kg/hm2) and N4 (96 kg/hm2) were set, with four times per treatment. Fertilization was performed twice in early July and early August 2021, and rhizosphere and non-rhizosphere soil samples of each treatment were collected for determination in September. The results showed that the nitrogen application level had significant effects on the content of alkali-hydrolyzed nitrogen in rhizosphere soil and the soil bulk density in non-rhizosphere soil (p<0.01), and had significant effects on the content of organic matter and available phosphorus in rhizosphere soil (p<0.05). In rhizosphere soil, soil water content increased with the increase of nitrogen application level. Soil pH value decreased slowly and reached the lowest value under N4 treatment. Under N3 treatment, alkali-hydrolytic nitrogen, available phosphorus and available potassium in rhizosphere soil were significantly increased by 8.92%, 44.38% and 16.00% compared with control group (p<0.05). Soil organic matter content was also significantly higher than that in control group (p<0.05). In non-rhizosphere soil, with the increase of nitrogen application level, soil alkali-hydrolytic nitrogen and available phosphorus contents increased first and then decreased, and the peak value was reached under N3 treatment (p<0.05). Soil pH value increased first and then decreased. The content of soil organic matter reached the peak value at the level of N4 (p<0.05). Under the same nitrogen application level, the contents of water content, available phosphorus and available potassium in rhizosphere soil were lower than those in non-rhizosphere soil except N3 level. pH, organic matter content and alkali-hydrolyzed nitrogen content of rhizosphere soil were higher than those of non-rhizosphere soil. The comprehensive analysis of grey correlation degree showed that N3 treatment and N4 treatments had the greatest effects on physicochemical properties and available nutrients of rhizosphere and non-rhizosphere soil, respectively.

    • XUAN Meiling, LIAO Shu, YUE Kai, WU Fuzhong, WU Qiuxia, ZHU Jingjing, NI Xiangyin

      2023,37(6):283-289,297, DOI: 10.13870/j.cnki.stbcxb.2023.06.036

      Abstract:

      To assess whether soil nitrogen leaching would be affected by the planting subtropical evergreen broad-leaved secondary forests of different ages and Chinese fir (Cunninghamia lanceolata) plantations, soil column microcosm in situ culture experiment was used to compare the soil total nitrogen, nitrate and ammonium concentrations and fluxes between 9-year-old and 45-year-old secondary forests (with Castanopsis carlesii as the dominant tree species), and between C. carlesii and C. lanceolata plantations (both 9-year-old). The results showed that: (1) The concentrations of total nitrogen and nitrate in the four forest soils showed a general pattern of 45-year-old secondary forest > 9-year-old secondary forest > C. lanceolata plantation > C. carlesii plantation. The concentration of ammonium nitrogen was 45 years old secondary forest > C. lanceolata plantation > 9 years old secondary forest > C.carlesii plantation. (2) The fluxes of total nitrogen and nitrate of the four forest types in soil leaching solutions were as follows: 9-year-old secondary forest > 45-year-old secondary forest > C. lanceolata plantation > C. carlesii plantation, and soil ammonium leaching fluxes varied significantly among the four forest types between may and August, showing a order of C. lanceolata plantation > 45-year-old secondary forest > 9-year-old secondary forest > C. carlesii plantation. (3) The annual leaching fluxes of total nitrogen were 14.24, 13.27, 7.26 and 10.97 g/(m2·a), the nitrate leaching fluxes were 10.88, 9.97, 5.35 and 8.44, and the ammonium leaching fluxes were 1.97, 2.18, 1.59 and 2.26 g/(m2·a), in the 9-year-old and 45-year-old secondary forests, C. carlesii plantation and C. lanceolata plantation, respectively. In summary, the leaching loss of soil total nitrogen and nitrate decreased along the growth of subtropical evergreen broad-leaved secondary forest age, but the plantations of C. lanceolata accelerate nitrogen leaching loss from soils relative to the native tree species.

    • WU Jin, LIU Yaojun, ZHENG Han, WANG Xi, LI Qi, XIE Wenbin, QIN Yue, DUAN Jian, LI Zhongwu

      2023,37(6):290-297, DOI: 10.13870/j.cnki.stbcxb.2023.06.037

      Abstract:

      In order to study the relationship between terrace wall stability and vegetation succession, the terrace walls of different vegetation restoration years (2 years, 5 years, 10 years, and 30 years) and different vegetation restoration stages (bare land, moss, moss-grass, and moss-grass-shrub) were selected as the research objects, and soil samples of surface (0—5 cm) and subsurface (5—20 cm) were collected. The effects of restoration years and succession stages on soil aggregates and their organic carbon were analyzed. The results showed that the content of soil macroaggregates (>0.25 mm) increased with the increase of succession stage, and the proportion of macroaggregates was higher with the longer recovery years of the same succession stage, and the proportion of macroaggregates reached 91.63% in the 30 years moss-grass-scrub stage. Soil mean weight diameter (MWD) and geometric mean diameter (GMD) in 0—5 cm and 5—20 cm soil layers showed a gradual increasing trend with the increase of restoration time, with 30-year soil MWD and GMD ranging from 1.07 to 1.41 and 0.88 to 1.17 mm, respectively, and showing the characteristics of moss-grass-scrub > moss-grass > moss > bare land in different succession stages. Soil organic carbon content was significantly correlated with macroaggregates (r=0.83, p<0.001), indicating that vegetation succession and planting years had positive effects on soil carbon sequestration. Vegetation succession and vegetation recovery time can improve soil structure, stability and corrosion resistance of soil aggregates. The research results can provide theoretical reference for optimizing terrace development.

    • CHEN Dongkai, LUO Han, XIE Yongsheng, Lü Jiaorong

      2023,37(6):298-304, DOI: 10.13870/j.cnki.stbcxb.2023.06.038

      Abstract:

      In order to improve the utilization efficiency of soil water and fertilizer, the water-collecting and impermeability measures suitable for the development of apple orchards in Weibei area were explored. Through field experiments, the effects of different water-collecting and impermeability measures on soil moisture, nitrate nitrogen and fine roots of dense planting dwarf rootstock apple orchard were analyzed. The results showed that: In the vertical direction, the treatment of seepage control layer, ridging coated, ridging laminating impermeable layer process could effectively increase the soil moisture content, nitrate nitrogen content and fine root length density of 0—40 cm soil layer, and the soil moisture content and fine root length density under the treatment of ridging coated and ridging laminating impermeable layer process were higher than those under the treatment of seepage control layer. The nitrate nitrogen content was lower than that under the treatment of seepage control layer. In the range of 50—100 cm soil layer, three processing measures all reduced soil nitrate nitrogen content, effectively alleviated the leaching accumulation of nitrate nitrogen. In the horizontal direction, the soil water content and root length density in the planting area (under plants and between plants) increased by 15.1%, 5.0%, and the nitrate nitrogen content decreased by 8.6% under the treatment of ridging coated and ridging laminating impermeable layer process. But there was no significant difference between the treatment of seepage control layer and clean tillage. In the fertilization area (midpoints), the three treatments increased the soil moisture content and the density of fine root length, and decreased the soil nitrate nitrogen content. Treatment of ridging laminating impermeable layer process had the best effect, which increased the soil moisture content and the density of fine root length by 48.6%,48.3%, respectively, and reduced the nitrate nitrogen content by 17.4%. Among all the measures, the treatment of ridging laminating impermeable layer process had the best control effect on orchard soil environment and fruit tree root system. The results of this study provided a reference for the application and popularization of the water-collecting and impermeability measures in dense planting dwarf rootstock apple orchard in Weibei area.

    • WANG Xin, WANG Ruoshui, CHEN Li, WANG Lisha, XIONG Chang, ZHANG Meng, DAI Houshuai, ZHANG Yanqin

      2023,37(6):305-314,324, DOI: 10.13870/j.cnki.stbcxb.2023.06.039

      Abstract:

      To investigate the effects of different drip irrigation belt layout modes on the distribution of soil phenolic acids, enzyme activities, and microorganisms in the fruit characteristics-crop intercropping system, and to preliminarily explore the relationship between soil phenolic acids and soil biological factors under intercropping drip irrigation conditions, a typical apple (Malus pumila L.)-soybean (Glycine max L.) intercropping system in the loess region of western Shanxi was used was the research object, with three types of drip irrigation belt spacing (L1, L2, L3). The spatial distribution changes of soil phenolic substances, enzyme activity, and microbial quantity under different water distributions were analyzed, and based on this, stepwise regression model was used to analyze the interrelationships among these three soil factors. The results showed that except for benzoic acid and phloroglucinol, the distance between drip irrigation belts had a significant impact on the distribution of phenolic acids (p<0.05), and had a significant impact on the enzyme activity and the distribution of microbial population except for catalase (p<0.05). In the vertical direction, different drip irrigation belt layout modes resulted in more distribution of phenolic acids in deep soil, the number of microorganisms and some enzyme activities first decreased and then increased with the deepening of soil layer in L1 and L2 treatments; In the horizontal direction, the effects of different drip irrigation belt layout modes on the distribution of soil phenolic acids, bacteria, and fungi were consistent with the intercropping control treatment, increasing with the increase of distance from the tree. Under the condition of drip irrigation, phenolic acids except p-hydroxybenzoic acid were significantly inhibited by urease, catalase and actinomycetes, and the total amount of phenolic acids in intercropping soil was less than that in monocropping. L1 treatment had the highest soil enzyme activity and total microbial biomass, while L2 treatment had the lowest accumulation of phenolic acids in the soil. Among them, L2 treatment had a relatively high level of soil enzyme activity on the basis of the lowest accumulation of phenolic acids. Therefore, it is recommended to adopt the pattern of arrange a drip irrigation belt at intervals of one row of soybean in the fruit-crop intercropping system, improving the soil micro-ecological environment can alleviate the inhibition of allelochemicals at the same time.

    • SONG Ying, GAO Mingxiu, XU Zexin, ZHAO Jinghui

      2023,37(6):315-324, DOI: 10.13870/j.cnki.stbcxb.2023.06.040

      Abstract:

      In order to clarify the multidimensional spatial distribution characteristics and the water-salt coupling relationship of soil salinity, the Shandong part of the Bohai Rim Plain was taken as the research area. Data were obtained through field measurements and indoor analyses, and descriptive statistical analysis of soil water-salt characteristics were carried out based on classical statistical methods. GIS software was used to analyze the two-dimensional spatial distribution of soil salinity and water content, and GMS software visualization was used to and analyze the three-dimensional spatial differentiation characteristics of soil salinity. A soil water-salt coupling coordination model was constructed to quantitatively analyze the degree of influence of different factors on water-salt coupling coordination. The results showed that: (1) The median soil salinity in the study area was 2.08 g/kg, with moderately saline soils dominating, and the overall soil salinity showed a gradual increase from top to bottom; the mean value of surface soil water content was 15.38%, and the whole region was relatively water-scarce. (2) In the two-dimensions, the area with soil water content less than 20% was 17 519.48 km2, which accounted for a total of 86.64%; the soil salinity in the surface layer (0—20 cm) was dominated by mildly saline soils, with an area of 10 051.87 km2, accounting for 49.71% of the total area. Soil water content and soil salinity both showed an increasing trend from south to north. (3) The water-salt coupling degree in the area north of Dongying District was mostly greater than 0.66, while the coupling degree in the area south (except Pingdu and Laizhou City) was mostly concentrated in the range of 0.40-0.66, forming a spatial pattern in which the intensity of water-salt interaction in the area north of Dongying District as a whole was greater than that in the area south. (4) The southern part of the study area was dominated by low coordination and medium coordination, while the northern part was dominated by higher coordination and high coordination. elevation, average temperature, average rainfall and NDVI had the strongest influence on the coordination of water-salt coupling, with correlation coefficients of 0.26, 0.25, 0.25 and 0.21 respectively. The results of the study can provide a theoretical basis for the rational development and utilization of saline soil resources in the Bohai Sea Plain region.

    • KONG Qianqian, ZHU Lianyong, ZHU Zhu, LUO Qi, ZHANG Lei, YAO Baolin

      2023,37(6):325-332, DOI: 10.13870/j.cnki.stbcxb.2023.06.041

      Abstract:

      To explore the differences and characteristics of the effects of different biochar additions on salinity and ion leaching in saline soil. This study used indoor soil column simulation experiments to add 0.5% of pig manure (PMB), cotton straw (CSB), and maize straw (MSB) biochar to the soil surface (0-10 cm), the leaching process was divided into three stages: rapid descent (P1), slow descent (P2), and stable descent (P3). To investigate the leaching effect of different biochar on salt ions in saline soil of southern Xinjiang, the infiltration rate, flow rate, cumulative leaching concentration of anions and cations, soil profile moisture content, and residual soluble ion content were measured. The results showed that compared to the treatment without adding biochar (CK), the application of biochar could improve the flow rate and infiltration rate of the leachate at each stage. During the rapid decline in electrical conductivity stage, the flow rate of CSB treatment increased by 20%, and the infiltration rate of PMB treatment increased by 29%. MSB treatment first reduced the EC value to 5 mS/cm, but the improvement in ion removal ability was small. The application of biochar had a certain impact on the sequence of ion leaching at each stage, that was, it promoted the leaching of Ca2+, Na+, SO42-, and Cl-, and inhibited the leaching of K+. At the end of leaching, biochar can significantly reduce the residual salt content of soil. CSB treatment can improve the water retention capacity of topsoil, keeping the sodium adsorption ratio (SAR) always at a low level and providing the best elution effect for residual anions in the soil. This shows that CSB treatment is a potential soil conditioner. The results provide theoretical reference for salinized soil improvement in southern Xinjiang.

    • LI Juan, ZHANG Yongfu, YU Tingting, YAN Ruiqi

      2023,37(6):333-340, DOI: 10.13870/j.cnki.stbcxb.2023.06.042

      Abstract:

      In order to monitor the spatiotemporal variations of ecological environment quality in the Aksu region comprehensively and timely, this study utilized the Google Earth Engine (GEE) platform to construct a remote sensing ecological index (RSEI) based on MODIS multispectral sensor data from 2005, 2010, 2015, and 2020. Additionally, the Moran index and Geo-detector were employed to investigate the spatial and temporal evolution of ecological quality and identify impact factors in the Aksu region. The findings indicated that: (1) The RSEI in the Aksu area increased from 0.24 to 0.27 between 2005 and 2020, exhibiting a fluctuating upward trend in ecological environmental quality. The high RSEI values were predominantly observed in the northern edge and central oasis region, while the low values were concentrated in the desert and Gobi region. (2) Throughout 2005-2020, the overall Moran index of the RSEI ranged between 0.80 and 0.87, signifying a strong positive correlation in the Aksu region, with high-high (H-H) and low-low (L-L) clusters being dominant. (3) From 2005 to 2020, the explanatory power of various factors in spatial heterogeneity (q-value) varied to different extents, with land use and rainfall identified as key drivers. Furthermore, the influence of interaction detection surpassed that of individual factors. This research provides valuable data and methodological references for the protection of the local ecological environment.

    • JIN Yiran, TAN Tenghui, TANG Qi, HUA Li, GUO Zhonglu

      2023,37(6):341-349, DOI: 10.13870/j.cnki.stbcxb.2023.06.043

      Abstract:

      The Northeast Black Soil Belt is a crucial commercial grain production base in China, in recent years, soil quality degradation, soil erosion and other issues have a direct impact on the security of ecology and security of food supply. In order to clarify the characteristics of land use change and evaluate the ecological sensitivity of the Northeast Black Soil Belt, we take the five periods of land use data of the Northeast Black Soil Belt in the years of 2000, 2005, 2010, 2015 and 2020 as the basis, and use the methods such as transfer matrices, geodetector, and comprehensive ecological risk evaluation to study the landscape pattern and ecological risk change trends. The results were as follows: (1) During the period of 2000—2020,unused land and water land use in the study area changed most obviously, increasing and decreasing by 1 035.7 and 975.8 km2, respectively, and arable land was the land use with more drastic changes in phases; (2) Different natural factors exhibited significant differences in explaining land use types in the study area. Temperature was the dominant factor influencing land use changes, while wind speed showed significant synergistic enhancement when interacting with elevation, temperature, evaporation, geothermy, atmospheric pressure, humidity and daylight duration factors in land use changes. (3) Over time, the overall ecological sensitivity of the study area has improved. Highly sensitive regions had decreased, mildly sensitive regions had increased. Additionally, there was a trend of high-value ecological sensitivity areas moving northward and low-value areas moving southward, the high-value ecological sensitivity regions may be related to erosion which dominated by wind erosion. The analysis of macro-scale landscape pattern changes and ecological risk assessment are of great significance to the formulation and implementation of regional ecological environmental protection policies.

    • HU Tao, SONG Zilin, GU Jie, WANG Xiaojuan, SUN Yifan, JIANG Lan, ZHANG Yiran, CHEN Zhihui, LIU Yucheng

      2023,37(6):350-357, DOI: 10.13870/j.cnki.stbcxb.2023.06.044

      Abstract:

      In order to investigate the pollution risk of multidrug-resistant bacteria in biogas residue from anaerobic digestion of cattle manure, five antibiotics (erythromycin, ampicillin, chlortetracyline, streptomycin and ciprofloxacin) that commonly used in livestock and poultry breeding were used to screen the culturable antibiotic-resistant bacteria from biogas residue of cattle manure. The results showed that the proportion of multidrug-resistant bacteria was as high as 76.5%, with 11 and 21 strains of bacteria resistant to five and four antibiotics, respectively. All multidrug-resistant bacteria were resistant to ampicillin, and bacteria resistant to erythromycin, chlortetracyline and streptomycin accounted for 92.0%, 89.3% and 61.3% of the total multidrug-resistant bacteria count, respectively. Through bacterial 16S rRNA sequencing, 32 strains with more than four kinds of resistance were identified as Shigella flexneri, Morganella morganii and Ochrobactrum pseudointermedia, respectively, all of which were important clinical pathogens. Resistance genes carried by seven typical multi-drug resistant bacteria strains were analyzed using whole genome sequencing, and a total of 28 antibiotic resistance genes were detected, corresponding to nine antibiotic resistance types. Analysis of the antibiotic resistance genes and insertion sequences locus information revealed that multidrug-resistant bacteria generally carried plasmids containing both resistance genes and insertion sequences, indicating that these resistance genes had high mobility and strong transmission risk. In conclusion, the biogas residue of cow manure contains a large number of multidrug-resistant bacteria, which can be regarded as a reservoir of antibiotic resistance genes, and attention should be paid to the environmental risk monitoring and assessment during the agricultural resource utilisation of biogas residue.

    • WANG Honghong, DONG Zhigang, ZHANG Yifan, FU Huifang

      2023,37(6):358-367, DOI: 10.13870/j.cnki.stbcxb.2023.06.045

      Abstract:

      In order to understand the Journal of Soil and Water Conservation, based on the full text database of China National Knowledge Infrastructure (CNKI) and the literature data of the journal, the bibliometric method was used to study and analyze the publication status of the Journal of Soil and Water Conservation from 2011 to 2022, understand its publication characteristics, development trend, and publication quality, and provide reference for the construction and development of the Journal of Soil and Water Conservation. The results show that a total of 3 948 papers were published in the Journal of Soil and Water Conservation from 2011 to 2022, with an overall upward trend in annual publication volume. The main disciplines of journal publication are agricultural basic science and agronomy. The ratio of paper funding shows a stepwise increasing trend, with a ratio of 1.00, and the number of publications for the fund projects is mainly from the National Natural Science Foundation of China, accounting for an average of 73.26%. The authors of the paper are widely distributed, mainly from 31 provinces (municipalities, autonomous regions) across the country, and are agricultural and forestry higher education institutions and research institutes. The total citation frequency of journals has maintained an increasing trend, and the citation frequency of influencing factors and articles has been increasing year by year, ranking in the Q1 zone of agricultural basic science disciplines. The overall influence of the Journal of Soil and Water Conservation is on the rise year by year. In addition to the authors of our school, we should also actively attract submissions from outside authors. The research results to some extent reveal the research hotspots and development trends of the soil and water conservation industry, which can provide scientific references for readers and related research.

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    • Spatiotemporal Characteristics of Land Use/Cover Changes in the Yellow River Basin over the Past 40 Years

      Liao Meiyu, Fang Xiuqin

      Abstract:

      The study of spatial and temporal characteristics of land use/cover is important for the conservation and rational development of land resources in the Yellow River Basin, and can provide important references for the implementation of ecological conservation and high-quality development strategies in the Yellow River Basin. The year-by-year land use/cover data of the Yellow River Basin from 1980 to 2021 was used to explore the land use/cover change characteristics of the Yellow River Basin for nearly 40 years by using Mann-Kendall and sliding t-test, geographic information TUPU, standard deviation ellipse and gravity center transfer model. The results show that (1) The forest, shrubland, water, and construction land significantly increasing and cropland, grassland, and wetland significantly decreasing from 1980 to 2021. (2) The periods of land use/cover change in the watershed can be divided into 1980-1992, 1993-2001, 2002-2012, and 2013-2021, and the quantitative structure is gradually characterized by rapid changes. The construction land, wetland and water are more sensitive to change. The land-use structure is gradually becoming more balanced, showing phased changes that are highly correlated with the implementation of major strategic measures and are more in line with the phasing. (3) The middle and upper reaches of the basin are dominated by the 2012-2021 and intermittent change type, interconversion of cropland and grassland, while the lower reaches are dominated by the 2001-2012 and 2012-2021 change type, conversion of cropland to construction land and grassland. Frequent changes are found in northern Ningxia, eastern Inner Mongolia and some areas distributed along the Yellow River system in the basin. (4) The centers of gravity of wetland, water and construction land all move westward, showing concentrated distribution to the southwest, scattered to the east and concentrated distribution to the northwest, respectively. The overall trend of land use structure has become better under the policy direction, and in the future we should focus on wetlands as well as areas with frequent land use changes.

      • 1
    • Freeze-thaw induced gully wall collapse and related factors in northeast China

      jia chen yang, zhang ke li

      Abstract:

      Gully erosion is one of the most important factors to cause land degradation. In the black soil area of northeast China, gully erosion is more severe and deeply affected by freeze-thaw effects. However, there is little research on the evaluation of freeze-thaw cycles (FTCs) on gully erosion. Due to the fact that gully wall collapse is the main response of gully erosion to FTCs, the contribution of FTCs to gully erosion can be evaluated by measuring the volume of gully wall collapse during FTCs. Between 2016 and 2018, field investigations were conducted on a total of 463 collapse points in 36 gullies. Based on the survey results, there are two main types of gully wall collapse: massy soil collapse and loose soil accumulation. At each collapse point, measure the morphological parameters of two types of accumulations, including the volume of collapsed soil, the width and depth of the gully cross-section, and the shear force and hardness of the corresponding gully wall soil. The result shows that: (1) the average strength of gully wall collapse caused by FTCs during the three-year study period is 16.12 m3/km/y. The two types of freeze-thaw collapse occur randomly within the gully, with the single point freeze-thaw collapse mainly concentrated in 0-3 m3, but massy soil collapse will produce a larger amount of soil. (2) the width and depth of gully cross-section is the most important factors to induce the collapse of gully wall, furthermore, the volume of collapse soil will quickly increase once the width to depth ratio>2.71. (3) the amount of gully collapse is also closely related to the shear force and hardness of the soil on the gully wall. The research results provide data support for quantitatively evaluating the contribution of FTCs to gully erosion.

      • 1
    • Effects of Contoured Reverse-Slope Terrace on the Microecology of Rhizosphere in Different Farming Systems

      LU Lianxin, ZHAO Yangyi

      Abstract:

      [Objective] To examine the impact of contoured reverse-slope terrace (CRT) on the microecological features of the rhizosphere in maize continuous cropping and maize-kidney bean rotation systems. [Method] Four treatments that were established comprise of continuous cropping on undisturbed sloping farmland (CK1), continuous cropping on contoured reverse-slope terrace (CRT1), rotational cropping on undisturbed sloping farmland (CK2), and rotational cropping on contoured reverse-slope terrace (CRT2). The maize-kidney bean rotation wheel was used as the research object, and the maize continuous cropping was used as the control. A combination of field in situ monitoring sampling and indoor experimental analysis was used. The crop root exudates and soil microbial community composition and structural characteristics of were analysed by GC-MS and high-throughput sequencing techniques. To reveal the effects of contoured reverse-slope terrace (CRT) on the species and content of root exudates and the composition and diversity of soil microbial community in maize continuous cropping and maize-kidney bean rotation. [Result] The results of the study showed that, (1) the changes in the relative content of root exudates were more prominent on CRT measures and more significant in the maize-kidney bean rotation. (2) The effect of CRT2 treatment on increasing the number, richness and diversity of soil microbial communities was more significant. (3) The correlation of root exudates, soil microbial community, and soil environmental factors was more significant in the CRT2 treatment than others, that under root exudates-soil microbial community interactions. [Conclusion] Contoured reverse-slope terrace changed the root exudates content of maize continuous cropping and maize-kidney bean rotation, and increased the number, diversity and richness of soil microbial community. And the enhancement effect of this measure in combination with maize-kidney bean rotation was better, and the improvement of root-soil microbial community was more significant. To provide a theoretical basis for growing crops on sloping arable land, choosing farming methods and improving the soil microenvironment and comprehensive management of soil erosion.

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    • Ecosystem service functions in the upper reaches of the Yellow River in Sichuan based on land use change value evaluation

      XU nuojin, YU xinxiao

      Abstract:

      Through the quantitative study of the relationship between land use change and ecosystem service value in the upper reaches of the Yellow River in the past 20 years, the comprehensive ecological management effect of the upper reaches of the Yellow River was evaluated, which provided a basis for improving the spatial planning, ecological environmental protection and management of ethnic regions, and promoted the high-quality development of the Yellow River Basin. Using the land use data of the Sichuan section of the upper reaches of the Yellow River in 2000, 2010 and 2020, the land use changes were analyzed based on the land use dynamics and land use matrix, and the economic value of the ecosystem service value equivalent in the Sichuan section of the upper reaches of the Yellow River was revised with reference to the equivalent ecosystem service value per unit area of the terrestrial ecosystem in China, and the impact of land use change on the ecosystem service value in the Sichuan section of the upper reaches of the Yellow River from 2000 to 2020 was quantitatively studied. The results show that: (1) From 2000 to 2020, the land use area of forestland, desert, wetland and water system in the upper reaches of the Yellow River in Sichuan showed an upward trend, while arable land, shrubs, grassland and glacial snow cover showed a downward trend, and the land use change in 2010-2020 was more significant than that in 2000-2010. (2) In 2000, 2010 and 2020, the value of ecosystem services in the Sichuan section of the upper reaches of the Yellow River was 1.27×1010 yuan, 2.51×1010 yuan and 3.92×1010 yuan, respectively, showing an upward trend, and sensitivity analysis showed that the analysis results were reliable. Among the land use types, grassland was the land with the most significant contribution to the total ecosystem value, with grassland ecological service contribution rates of 93.9% and 72.9% in 2000-2010 and 2010-2020, respectively, followed by wetland and forestland. (3) In the study area, the value of each individual ecosystem service showed an increasing trend in 20 years, and the sub-values of regional ecological service functions were all regulation services> support services> supply services > cultural services, and climate regulation, hydrological regulation, soil conservation and biodiversity were the most significant service values among the 11 individual functions, and the sum of the four accounted for more than 58.5% of the total value. Land use change in the upper reaches of the Yellow River in Sichuan will affect the change of regional ecosystem service value, with grassland having the most significant impact, followed by wetlands and forest lands. The results of ecological governance have gradually increased in the past 20 years, and the ecological environment has continuously improved.

      • 1
    • Analysis on the Evolution Characteristics and Driving Forces of Territorial Space Pattern in the Qinling-Daba Mountain Area

      YINLI, WEIWEI

      Abstract:

      [Objective]To scientifically understand the spatio-temporal evolution and driving mechanism of urban space, agricultural space and ecological space in the Qinling-Daba Mountain area is of great significant. [Methods]Therefore, based on the methods of land transfer matrix, topographic position analysis and random forest regression, this paper studies the evolution characteristics and driving mechanism of 'three-function space' in the Qinling-Daba Mountain area from 2000 to 2020. [Results]The results show that: (1) In the past 20 years, the urban space in the Qinling-Daba Mountain area have been expanding violently, and the agricultural and ecological space has been shrinking continuously. The population of the counties which account for 58.33 % of the total population has been decreasing, while the urban space is still expanding. There is a serious differentiation between population growth and urban expansion. (2) The urban and agricultural space is gradually increasing, and the ecological space is decreasing. The new urban and agricultural space is moving up 1~2 terrain positions on average, and the downstream Danjiangkou Reservoir heightening project has a significant indigenous impact on the spatial distribution gradient of the overall land in mountainous areas. (3) The dynamic cross-conversion between agricultural space and ecological space is the dominant type of the study area, and the influence of fiscal expenditure on it is the most obvious. Agricultural space is the main source of new urban space, and the scale of urban degradation into agricultural and ecological space is remarkable. (4) Land development policy, mountainous terrain attributes, traffic location conditions and socio-economic factors jointly restrict the evolution results. The intensity of each type of factors in different transformation directions and the number of prominent indigenous factors are significantly different.[Conclusion] The optimization of the land spatial pattern in the study area can be concentrated from the newly added towns to the key development zones, scientifically guide the agricultural and ecological space to conform to the terrain gradient layout, carefully carry out the construction of water conservancy projects, and plan the overall layout of the "Three zones and Three lines" in the region.

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    • Response and Mechanism of Source-sink-transportation During the Compensation Effects of Post-drought

      Li Tao-Tao, Wang Shiwen

      Abstract:

      Crops often suffer from interval drought and rehydration (rainfall or irrigation) during the whole growth period, especially in arid and semi-arid areas. Under drought stress, the growth and development of crops are inhibited, and the yield is reduced; meanwhile, the plants drought tolerance will be induced. In order to compensate loss of yield or growth induced by drought stress, rehydration after drought stress shows compensatory growth, which produces compensation or even over compensation effect on yield. The compensation effect of post drought is the result of crop's positive response to drought stress and compensatory growth after rehydration. It can effectively improve crop yield and water use efficiency in crop production in arid areas. Source sink relationship is widely used to explain the crop yield formation, and regulating the source sink relationship is one of key way to improve crop yield. The compensation effect of post drought is highly related to the source sink response of crops. Based on the current research progress, this paper tries to explain the compensation effect of post drought in source and sink way. Under the drought stress, in the source, the stomata were closed, photosynthesis was decreased and soluble carbohydrate accumulation was increased, while sink activity was often increased. After rehydration, the metabolism of soluble carbohydrate in the source (leaf) was enhanced, which enhanced the photosynthesis and the ability of carbohydrate synthesis; meanwhile, the sink activity (grain) was maintained at a high level, and the rate of assimilate unloading and accumulation was accelerated; the assimilate in the flow remained at a high level. During this process, the activities of sucrose invertase (INV), cell wall invertase (CW-INV) and 1-FEH w3 play important roles in the source sink response to the compensation effect of post-drought. This paper integrated the mechanism of compensation effect of post drought in the perspective of source sink relationship, which provides a theoretical basis for understanding the mechanism of compensation effect of post drought and improving crop water efficient in arid areas.

      • 1
    • Effects of nitrogen and phosphorus additions on aggregate-associated soil carbon and interactions with phosphorus fractions in evergreen broad-leaved forest

      He Lingyun, Wang Fangchao

      Abstract:

      In order to explore how phosphorus input regulates the effects of atmospheric nitrogen deposition on soil aggregate organic carbon content and the coupling relationship between carbon and phosphorus, a long-term monitoring test platform for nutrient addition for 6 years (2015-2021) was established in the soil of evergreen broad-leaved forest, including 4 treatments: Control (P0+N0, 0 kg P ha-1 a -1 +0 kg N ha-1 a -1), nitrogen addition (P0+N100, 0 kg P ha-1 a -1 +100 kg N ha-1 a -1), phosphorus input (P50+N0, 50 kg P ha-1 a -1 +0 kg N ha-1 a -1) and nitrogen and phosphorus were simultaneously input (P50+N100, 50 kg P ha-1 a -1 +100 kg N ha-1 a -1), 3 replicates were performed, and a total of 12 plots were obtained. 0-10 cm soil samples were collected from the sample site in August 2021 to determine the basic physical and chemical properties, soil particle size distribution, phosphorus components of soil aggregates of different particle sizes, and organic carbon (SOC) content. The results showed that: (1) Under P0 (0 kg P ha-1 a-1 without P input) treatment, nitrogen addition significantly increased the proportion of large aggregates, reduced the content of clay and powder particles, and increased the SOC content of each aggregate particle size. Nitrogen addition significantly decreased and increased the content of LP and RP components in aggregate clay and powder, respectively. (2) Under P50 (50 kg P ha-1 a-1 with P input) treatment, nitrogen addition significantly increased the mean geometric mass diameter (GMD) of soil aggregates, and increased the proportion of large aggregates while decreased the proportion of small aggregates. Nitrogen addition had no significant effect on the content of phosphorus and SOC in aggregates of different particle sizes. (3) Under P0 treatment, soil aggregate SOC showed a positive correlation with refractory phosphorus. Under P50 treatment, SOC of soil aggregates had no significant correlation with all functional phosphorus components. It is concluded that under P0 treatment, nitrogen addition can increase soil organic carbon retention by increasing the insoluble phosphorus in aggregate viscosity and powder particle size of evergreen broad-leaved forest. Under P50 treatment, the effect of nitrogen addition on organic carbon in each particle size may be regulated by biological factors and has nothing to do with the availability of phosphorus. In conclusion, the effect of nitrogen deposition on the coupling relationship between carbon and phosphorus in soil aggregates in evergreen broad-leaved forests is regulated by phosphorus. The results of this study provide data support for the response of forest soil carbon cycling to global climate change.

      • 1
    • Surface particle size characteristics of dry lake beds in grasslands and their effects on dust release

      lisiyao, mengzhongju

      Abstract:

      [Objective] In order to explore the typical surface wind erosion process of the dry lake basin and the mechanism of the formation of saline-alkali dust storm. [Methods] Taking the Chagannaoer dry salt lake in Abaga Banner of Xilin Gol League as the research object, four typical surface ( crust surface, broken surface, activated surface and desertification surface ) were selected according to the dynamic evolution process of salt lake surface from the center of the lake to the shore of the lake. The characteristics of soil particle size distribution, wind speed profile and sediment transport law near the surface from the center of the lake to the shore of the lake were analyzed. [Results]The results show that : (1) From the center of the lake to the shore of the lake, the grain size of 0 - 2 cm sediment particles on the surface shows a trend of gradually thickening, and mainly clay and silt ; (2) The wind speed from the center of the dry salt lake to the shore of the lake showed a decreasing trend. The wind speed profiles of different surfaces basically conformed to the logarithmic distribution of Karman 's velocity, and the fitting effect was good (R2 > 0.9). (3) The amount of sediment transport on the broken surface is the largest, which is about 50 times that of the crust surface, and the sediment transport rate on the crust surface shows a linear law with the change of height due to limited dust supply (R2 = 0.8), and the sediment transport rate on the other three surfaces shows an exponential function with the change of height (R2 > 0.97). (4) At the height of 0~50 cm near the surface, the average particle size of the sand particles carried in the wind-sand flow is between 6 ~9 Φ, which belongs to the silt, and the sorting is poor. The skewness is mainly negative, and the kurtosis is mainly medium and sharp. [Conclusion]On the whole, the wind erosion effect on the broken surface is the strongest, and the wind erosion effect on the crust surface is the weakest. The wind erosion effect in this area can be weakened by increasing the critical starting wind speed threshold of sand particles and the coverage of underlying surface.

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    • Effects of Mushroom Residue Organic Fertilizer Combined with Desulfurized Gypsum on Active Organic Carbon and Its Sensitivity in Saline-Alkali Soil of the Yellow River Delta

      li chuan fu, li yong qiang

      Abstract:

      Abstract: [Objective]The soil salinization in the Yellow River Delta seriously restricts the efficient utilization of soil resources and sustainable development of agriculture. The application of amendments is an effective measure to improve saline-alkali soil in coastal areas. [Methods]In order to explore the effects of mushroom residue organic fertilizer and desulfurized gypsum on the organic carbon components and carbon pool management index (CPMI) of saline-alkali soil, the wheat-maize rotation land in the newly reclaimed of Yellow River Delta was used as the research object, and the randomized block experiment method was conducted to set up four treatments: no fertilization (CK), farmers' common fertilization (CN), mushroom residue organic fertilizer (MCOF), mushroom residue organic fertilizer and desulfurized gypsum (MCOG). Through three years of field experiments, [Results] the results showed that the combined application of mushroom residue organic fertilizer and desulfurized gypsum significantly reduced soil pH, electrical conductivity and alkalinity in 0~20 cm soil layer, and increased soil nutrition content and cation exchange capacity (P<0.05). The contents of total organic carbon (TOC), easily oxidized organic carbon (EOC) and microbial biomass carbon (MBC) in 0~20 cm soil layer were higher than those in 20~40 cm soil layer, while the water-soluble organic carbon (WSOC) was lower than that in 20~40 cm soil layer. In the 0~20 cm soil layer, compared with CN treatment, MCOG treatment significantly increased soil TOC, EOC, WSOC, and MBC by 15.48%, 23.50%, 18.98%, and 51.40%, respectively. The effective rates of EOC and MBC were increased by 13.94% and 30.49%, respectively. There was no significant effect on the effective rate of WSOC. The combined application of organic fertilizer and desulfurized gypsum significantly increased the soil CPMI, which increased by 15.38% and 20.00% compared with CN and CK treatments, respectively. The sensitivity index of MBC was higher than that of other organic carbon components, and the MBC value of MCOG treatment was the highest. Correlation analysis showed that soil TOC content depended on its active components, while the main factors affecting the content and effective efficiency of organic carbon active components, as well as the CPMI, are pH, CEC, and EC. [Conclusion]Therefore, the combined application of mushroom residue organic fertilizer and desulfurized gypsum can significantly decrease soil alkalinity, improve soil fertility and enhance carbon sequestration efficiency of saline-alkali soil, this research provides theoretical basis and data support for expanding organic improvement methods in saline-alkali soil of the Yellow River Delta.

      • 1
    • Response of soil carbon and nitrogen fractions in marshy meadow soils of Gahai wetland area to warming and nitrogen application

      luzhaoyang, maweiwei

      Abstract:

      To examine the attributes of soil carbon and nitrogen fractions in alpine wetland soils under the influence of climate warming and nitrogen deposition, a study was conducted. Four treatments were established, namely control (CK), warming (W), nitrogen application (N), and warming nitrogen (WN). These treatments were designed to simulate potential future scenarios of climate warming and nitrogen deposition in a swamp meadow located in the Gahai Wetland Area. The soil carbon and nitrogen levels were quantified a year and a half following the completion of the experiment.. The results showed that: 1) The utilization of the open top box warming device resulted in a notable elevation of the mean temperature within the 0-15 cm soil layer by 0.53°C. Additionally, this intervention led to a significant decrease in the water content (SMC) and pH levels, as well as the concentrations of soil total nitrogen (TN), microbial nitrogen (MBN), ammonium nitrogen (NH4+-N), organic carbon (SOC), and soluble organic carbon (DOC) within the 0-10 cm soil layer. Conversely, there was an observed increase in the concentration of nitrate nitrogen (NO3--N)..2) Nitrogen application considerably lowered the contents of NH4+-N and SOC in all soil layers, as well as the contents of microbial biomass carbon (MBC) and DOC in soil layers 10-20 cm deep, but increased the contents of TN, MBN, and NO3--N. 3) The application of nitrogen through warming conditions resulted in a large rise in SMC, TN, NO3--N, and MBC content. Conversely, it led to a significant reduction in MBN, NH4+-N, and DOC.. 4) Correlation analysis showed that there was a positive correlation between soil moisture and all physicochemical factors, and soil carbon and nitrogen components were positively correlated.. The results indicated that the simulated warming application of nitrogen alleviated the temperature and nitrogen limitation of plant growth in the Gahai wetland, promoted the accumulation of TN, and had a greater impact on the soil microbiota carbon and nitrogen fractions, which led to the conversion of soil microbial carbon and nitrogen activities and distribution characteristics.

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    • Effects of Erosive Rainfall on Soil Erosion Characteristics of Black Sloping Farmland

      DING Guihui, ZHANG Xingyi

      Abstract:

      [Objective]Rainfall is the driving force of hydraulic erosion in black soil sloping farmland. It is of great significance to study soil erosion characteristics under natural rainfall conditions for soil erosion control. [Methods]Based on 43 erosive rainfall events observed at different ridge-row runoff plots (3°, 5° and 7°) along the slope in Guangrong Small Watershed, Hailun City, Heilongjiang Province during 2021-2022, K-mean clustering method was used to compare the characteristics of runoff and sediment transport under different rain patterns and slopes, and the influencing factors on runoff and sediment transport were discussed. [Results]The results show that the rainfall of short duration, heavy rain and light rainfall (rain type 3) is the main one, followed by the rainfall of medium duration, medium rain intensity and medium rainfall (rain type 2), and the rainfall of long duration, light rain intensity and heavy rainfall (rain type 1) rarely occurs. Under the same rain pattern, the cumulative runoff depth and sediment transport increased with the increase of slope. Under the same slope, different rainfall types have different responses to cumulative runoff depth. Overall, rainfall type 3 has the highest contribution (50.9%-57.9%), rainfall type 2 has the second contribution (37.6%-44.1%), and rainfall type 1 has the lowest. In the event of rain type 2, rainfall erosivity and slope have direct influence on runoff depth, and runoff depth and slope have direct influence on sediment transport. In the event of rain type 3, rainfall erosivity affects runoff depth and then sediment transport through direct and indirect effects. [Conclusion]For all rainfall-type events, rainfall erosivity and slope are the main controlling factors affecting the runoff depth, and the runoff depth and slope are the main controlling factors affecting the sediment transport.

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    • Effects of Different Ecological Measures on Water Use Characteristics of Amorpha fruticosa in Open Pit Coal Mine Areas

      BI Yinli

      Abstract:

      [Purpose] To explore the water use characteristics of typical plants under different ecological measures in the waste dump, improve plant water use efficiency, and accelerate the ecological restoration process in the mining area. [Method] Six ecological measures (control, inoculation, green fertilizer, inoculation+green fertilizer, inoculation+weathered coal, inoculation+green fertilizer+weathered coal) were taken from the waste dump of the Heidaigou Coal Mine to treat Amorpha fruticosa. The stable isotopes of hydrogen and oxygen in water were combined with other methods. [Result] (1) The soil volume moisture content of the waste dump is 3% to 9%, which is lower in 0-30, 70-100 cm soil layers, and higher in 30-70 cm soil layers. (2) The water supply of Amorpha fruticosa comes from precipitation and soil water. The soil water undergoes significant fractionation in the 0-30 cm soil layer, and shows significant differences in different ecological measures, with green fertilizer treatment being the largest and inoculation+green fertilizer treatment being the smallest. (3) There were significant differences in the water use characteristics of Amorpha fruticosa under different ecological measures. The inoculation treatment had a higher water use ratio of 53.4% in the 50-100 cm soil layer; Green fertilizer treatment mainly utilized surface (0-20) soil water, which was 42.6%; The treatment of inoculation and green fertilizer had a relatively uniform proportion of soil water use in each layer. [Conclusion] The inoculation + green fertilizer treatment optimized the water use characteristics of Amorpha fruticosa, increased the utilization ratio of surface and deep water, and can be used as an ecological reclamation measure for waste disposal sites, which promoted the ecological recovery rate and effect of arid mining areas in the western region.

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    • Research progress and prospect of mechanical effects and model construction of root-soil complex

      XieXiangrong, ZhangChuan

      Abstract:

      The characteristics and interaction between plant roots and soil are the key to ecological slope protection. In this paper, the concept and connotation of root-soil complex, the mechanical effect of root-soil complex and the principle, advantages and disadvantages and application scope of mechanical model are summarized and analyzed by literature analysis and comparative analysis. The results show that the root-soil complex is a complex and stable whole based on the coupling relationship of mechanical effects between roots and soil, and the roots are intertwined in the soil, which plays a similar role in strengthening fibers. The mechanical relationship between root and soil is essentially a result of the interaction of soil force, hydraulic force and composite mechanical characteristics of root-soil complex. The soil force characteristics focus on the influence of plant root characteristics on soil, the hydraulic characteristics focus on the influence of water movement and water holding capacity in soil on soil structure, soil physical and chemical properties and root characteristics, and the composite characteristics focus on the direct influence of soil characteristics on plant root characteristics and structure, so that the mechanical relationship between root and soil is in a dynamic balance through the interaction of the three. The research on the composite mechanical model of root-soil complex is slightly less than that of soil force and hydraulic model. The soil mechanical model focuses on the relationship between roots and soil characteristics through experiments and formulas to quantify the reinforcement of roots, while the hydraulic characteristic model quantifies the hydraulic characteristic parameters through numerical simulation, both of which measure the soil consolidation effect according to the comparison between parameters. However, composite mechanics involves both soil and hydraulic characteristics, so it should be the key research direction in the future. In the future, the effects of freeze-thaw cycle, dry-wet alternation and dry-hot cycle on root-soil interaction in different regions, the shear strength of multi-type plant mixtures, the influence mechanism of chemical and microbial effects on soil-water characteristics and the construction of composite models need to be further studied. This paper can provide important theoretical value and engineering reference for vegetation restoration, soil and water conservation and sustainable development in ecologically fragile areas.

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    • Impact of Initial Soil Moisture and Rainfall Energy on Splash Erosion Characteristics of Black Soil Aggregate

      ZHANG Zhuanmin, WANG Bin

      Abstract:

      To investigate the influence of rainfall energy and initial moisture content on the mechanism of soil aggregate splashing erosion, a typical cultivated black soil from the Northeastern region of China was selected as the research object. Artificial simulated rainfall experiments were conducted to explore the splashing erosion characteristics of soil aggregates with varying initial moisture content, rainfall energy, and initial particle size of aggregates. Results showed that: (1) the splash erosion of the soil aggregates was highest when the initial soil moisture level was 4%. Additionally, among the four different initial aggregate size groups, the aggregates with an initial particle size <0.25 mm experienced the greatest splash erosion. In fact, their splash erosion was1.21-5.50 times greater than the other three particle size groups under the same rainfall energy conditions. Furthermore, as the initial soil moisture increased, the splash erosion of the aggregates within each particle size group decreased initially, but then started to increase once the initial soil moisture surpassed 25%. (2) The splash erosion of the black soil aggregates increased with the increase alongside higher rainfall energy. When the rainfall energy reached 909 (J/m2)/h (equivalent to 5 m), the splash erosion of the different-sized black soil aggregates increased significantly. For aggregates with an initial particle size of <0.25 mm, the splash erosion rose by 15.37-20.70 times compared to the rainfall energy of 305 (J/m2)/h (equivalent to 1 m). Similarly, for particle size ranging from 0.25-1 mm, 1-3 mm, and 3-5 mm, the splash erosion increased by 52.30-417.60 times, 51.58-359.36 times, and 68.73-777.99 times, respectively. Notably, a clear threshold was observed for splash erosion of aggregates with different initial particle size. When the rainfall energy exceeded 529 (J/m2)/h (equivalent to 2 m), there was a significant difference in splash erosion between different rainfall energy gradients. (3) The analysis highlighted that rainfall energy was the primary factor affecting splash erosion. It exhibited a direct effect with a correlation coefficient of 0.811, demonstrating a significant positive influence. Conversely, the direct effects of initial soil moisture and initial particle size of aggregations were significantly negative, with correlation coefficients of 0.193 and 0.352, respectively. The research findings can provide a scientific basis for investigating the mechanisms of slope soil erosion in the black soil regions of Northeast China, as well as for establishing process-based models for soil erosion.

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    • Analysis of spatial and temporal evolution and dynamic driving force of soil erosion in the middle reaches of the Yellow River in the rich and coarse sendiment area

      zhangzhuopei, niujianzhi

      Abstract:

      [Objective] To reveal the spatial and temporal evolution characteristics of soil water erosion in the middle reaches of the Yellow River in the rich and coarse sediment area from 2000 to 2020, and analyze its dynamic driving force. [Methods] Based on the RUSLE model, calculate the year-by-year soil water erosion modulus in the rich and coarse sediment area, analyze the change characteristics of soil water erosion intensity in 2000, 2005, 2010, 2015, and 2020, and explore the spatial-temporal characteristics of soil water erosion modulus by using the Sen+MK trend analysis method combined with the Hurst index, and use the factor probing in the parameter-optimal geographical detector with the interactive probing to quantify the explanatory power of six factors, namely, average annual precipitation, elevation, slope, vegetation cover, land use/cover type, and soil type, on the spatial distribution of soil water erosion. [Results]: (1) The area of moderate, intense, very intense, and intense erosion in the rich and coarse sediment area decreased by 48.09%, 77.93%, 83.01%, and 36.13%, respectively, and the area of slight and mild erosion increased by 46.22% and 0.33%, respectively, in the five-period from 2000 to 2020. At this stage, the sandy and coarse sandy area is dominated by slight and mild erosion, and the area of the two is 62.49% and 42.07% respectively. (2) The overall inter-annual change of soil water erosion modulus in the rich and coarse sediment area shows a fluctuating and significant downward trend, from 2,214.89 t/(km2·a) in 2000 to 1,169.44 t/(km2·a) in 2020, and the spatial change of soil water erosion modulus in the rich and coarse sediment area from 2000 to 2020 is mainly in a decreasing state, with an area of 76.13%, and the future area of the rich and coarse sediment area is 76.13%. The spatial change trend of soil water erosion modulus in the sandy and coarse sandy area from 2000 to 2020 is mainly in a decreasing state, with an area share of 76.13%, and the future will still be mainly in a decreasing state, with an area share of 62.50%. (3) The explanatory power of the interactions among the six factors is greater than that of a single factor, and it is mainly manifested as nonlinear enhancement and two-factor enhancement; soil water erosion in the rich and coarse sediment area is dominated by precipitation and land use/cover in 2000-2005, and is dominated by vegetation cover and land use/cover in 2010-2020. [Conclusions]: The soil water erosion condition in the rich and coarse sediment area improved continuously from 2000 to 2020; in the future, a total of 62.50% of the area soil water erosion modulus is in the state of continuous decline and future decline, but there is still a potential risk of increase in 20.44% of the area; the land use/cover pattern was changed by the project of returning farmland to forests and grassland, which made the soil water erosion in the rich and coarse sediment area The driving force of soil water erosion in the rich and coarse sediment area changes dynamically; the slope factor needs to be fully considered when optimizing the land use/cover pattern for the prevention and control of soil water erosion in the rich and coarse sediment area in the future.

      • 1
    • Evaluation of Land Use Change and Carbon Storage in Fujian Province Based on PLUS-InVEST Model

      Huang Tao

      Abstract:

      Fujian Province has a forest coverage rate as high as 66.8%, which ranks first among all provinces in China in terms of forest coverage rate. [Purpose]The purpose of this study is to investigate the impact of land use changes on the spatial and temporal variations of carbon storage in Fujian Province and aim to provide a theoretical basis for exploring the balance between social development and ecological protection. [Method] Based on the PLUS model and the InVEST model's carbon storage module, this study examines the relationship between the spatiotemporal change characteristics of carbon storage and its correlation with land use types in the province from 2000 to 2020. Furthermore, the spatial and temporal changes in carbon storage in Fujian Province from 2020 to 2030 were predicted from three scenarios: natural development, ecological protection and urban development. [Results] The study reveals that the total carbon reserves in the study area in 2000, 2010 and 2020 were 214.77×107, 214.51×107 and 212.93×107 t respectively, indicating a downward trend over the years. The development and transformation of land by human activities is the dominant factor leading to changes in carbon stocks. The conversion of large areas of cultivated land and forest land into urban areas is the primary reason for the decline in carbon stocks. The prediction results show that compared with 2020, carbon storage under the scenarios of natural development, ecological protection, and urban development in 2030 will decrease by 1.47×107 t, increase by 0.17×107 t, and decrease by 1.85×107 t respectively. The ecological protection scenario is the only development scenario that can reverse the decline in carbon stocks. Compared to 2020, the forest area has expanded by 1,900.87 km2 and the forest carbon storage has increased by 2.08 ×107 t. This can effectively protect the ecology while also meeting the land requirements for urban development. [Conclusion] Therefore, prioritizing forest land protection and controlling the expansion of construction land are crucial prerequisites for Fujian Province to achieve carbon peaking and carbon neutrality goals.

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    • Effect Of Soil Aggregate on Preferential Path in Gully System of Dry-hot Valley

      lizhuyu, Zhao Yang Yi

      Abstract:

      [Objective] To investigate the impact of soil aggregate structure on the formation of preferential pathways in the gully system of the dry-hot valley of the Jinsha River and enhance our understanding of soil moisture and solute transport in the gully system. [Method] We selected different sections (catchment area, gully head, gully bed, and gully bottom) of both active and stable gullies in the dry-hot valley of the Jinsha River as our research subjects. We used staining tracers and morphological image analysis techniques to extract the preferential pathways of the soil level profile. Moreover, we employed RDA, gray correlation, and coupled coordination analysis to explore the relationship between soil aggregate structure and preferential pathways. [Result] (1) Soil aggregates in stable gullies were more stable than those in active gullies. Except for specific soil layers, the contents of mechanically stable aggregates (>0.25 mm, DR0.25) and water-stable aggregates (>0.25 mm, WR0.25) and average mass diameter (MWD) in the four parts of the active gully were significantly lower than those in the stable gully (p < 0.05). The aggregate destruction rate (PAD) and unstable aggregate index (ELT) showed the opposite trend. As the gully system extends from the catchment to the bottom of the gully, the fraction of large soil, and the stability of aggregates all decreased. (2) The number and connectivity of preferential pathways in active gullies exceeded those in stable gullies. However, the connectivity of the preferential pathways in the gully system deteriorated as it extended from the catchment to the bottom of the gully. The preferential pathways with a diameter >10 mm served as the primary channel. The Simpson index of active gullies exhibited an increase of 3.12% compared to stable gullies, indicating a higher richness of preferential pathways across different diameter classes. (3) The stability of soil aggregates affected the formation and distribution of preferential pathways. Remarkably, there is a strong correlation between soil aggregate structure and the number of preferential pathways, with MWD and WR0.25 of showing the most substantial effect on the number of preferential pathways (p < 0.01). (4) As the gully system extended from the catchment to the bottom of the gully, the coupling coordination between the soil aggregate structure and the preferential pathways decreased. Overall, the order of performance was as follows: gully head > catchment area > gully bottom > gully bed. [Conclusion] Soil aggregate structure is one of the important driving factors for the formation of preferential paths, and the distribution of preferential paths has a significant impact on the development of gully systems in dry-hot valleys.

      • 1
    • Effects of slope and rainfall intensity on sediment yield in the colluvial deposits of southern Guangxi under simulated rainfalls

      changzhiyong

      Abstract:

      [Purpose] This study aims to reveal the influences of slope gradient and rainfall intensity on the sediment yield characteristics of the colluvial deposits from Benggang and provide scientific basis for soil loss prediction and control of the colluvial deposits in southern Guangxi. [Method] The soil samples from Baisha Town, Hepu County were selected as the research object. The indoor experiment of simulated rainfall was carried out to investigate the sediment yield characteristics under different slope gradients (15°, 20°, 25°) and rainfall intensities (60, 90, 120 mm/h). [Results] The results showed that the variation processes of the erosion rate of the colluvium were relatively stable, and the erosion rate was mostly lower than 5.0 g/m2/s and showed a certain downward trend when the rainfall intensity was 60 mm/h under different slope conditions. While, the erosion rate fluctuated to increase first, and then decreased under the rainfall intensity of 90~120 mm/h. The maximum erosion rate during each rainfall increased with the increase of rainfall intensity and slope gradient, and the maximum erosion rate occurred within 0~25 min, and tended to advance with the increase of slope gradient. The sediment yield amount (3.64~48.07 kg/m2) increased with the increase of rainfall intensity and slope gradient, and the nonlinear regression result between the sediment yield amount and the two factors (a power function) was better than the linear regression result. The correlation between sediment yield amount and the interaction of slope and rainfall intensity was the most significant and showed a high-significant linear function relationship. [Conclusion] The sensitivity coefficient of the sediment yield amount to rainfall intensity was higher than that of slope, and the influence of rainfall intensity on sediment yield was stronger than slope. Slope drainage measures should be taken in the prevention and control of colluvial deposit erosion.

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    • Effects of Different Thickness of Degradable Plastic Film on the Loss of Dissolved Nitrogen and Phosphorus in Sloping Farmland

      Wang Kaili, Fang Nufang

      Abstract:

      Soil nutrient loss of slope farmland can lead to land degradation and non-point source pollution. Degradable mulch film not only has the advantages of polyethylene mulch film, but also is easy to degrade, and is widely used in cultivated land planting. However, the mechanism of its effect on soil nutrient loss is still unclear. To explore the effects of degradable mulch film mulching on runoff and loss of dissolved nitrogen and phosphorus, polyethylene film mulching (PF) with a thickness of 0.003 mm, degradable film mulching with a thickness of 0.006 mm (BF1), 0.008 mm (BF2), 0.010 mm (BF3) and 0.012 mm (BF4), and no mulch (CK) were set up. In in-situ runoff plots, using mulching on ridge tillage peanut planting as the study object, the runoff and concentration of ammonium nitrogen (NH4+-N), nitrate nitrogen (NO3--N), and available phosphorus (PO43--P) in runoff under natural rainfall conditions were measured, and the runoff and nutrient loss characteristics under different thickness of degradable mulch film were analyzed. The results showed that: (1) The degradation time of degradable film increased with the increase of film thickness. (2) The order of cumulative runoff was BF1<BF2<BF3<PF<CK<BF4, and there was significant difference between BF1 and BF4 (P<0.05). (3) Compared with CK, different film mulching can reduce the cumulative loss of nitrogen and phosphorus to varying degrees. BF1 had the most significant effect on reducing the loss of NH4+-N and NO3--N, while BF2 had the most significant effect on reducing the loss of PO43--P. (4)The loss of NO3--N and PO43--P in BF4 was higher than that in other mulches, while the loss of NH4+-N in BF3 was higher than that in other mulches. The results can provide a theoretical basis for the prevention and control of water, soil, and nutrient loss in sloping farmland mulching with plastic film and solving the problems of agricultural non-point source pollution, which is of great importance for the development of green agriculture and sustainable ecological.

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    • Evaluation of the accuracy of extraction of slope and length based on DEM of GF-7 satellite

      Zhao Yunlong, Fu Suhua

      Abstract:

      [Purpose] Slope and slope length are essential topographic factors affecting soil erosion process, and thus should be accurately estimated for erosion modelling. The Gaofen-7 satellite is known for its capacity of high-precision elevation measurement, and therefore holds a great potential for a high-quality extraction of the topographic factors such as slope and slope length. This study aims to evaluate the performance and accuracy of Gaofen-7 satellite in terms of deriving slope and slope length. [Methods] DEMs generated from the GF-7 satellite images, 1:10 000 topographic map and LiDAR images were processed using LS calculation tool to derive slope and slope length for four small watersheds in WuBu County, Shaanxi Province. Performance indicators including correlation coefficient (r), relative bias (RE) and absolute bias (AE) were used to estimate the discrepancy between different data sources. [Results] The results show that: (1) the elevation data of the three sources have extremely strong correlations (r>0.956). Compared with the topographic map and LiDAR, the watershed-average slope derived from GF-7 is lower by 7.50%~9.02% while slope length is higher by 1.83%~19.35%. However, the area distributions of slope length and slope derived from the three data sources have no significant difference. (2) Comparing the results of slope and slope length, the discrepancy in slope (RE: 16.46%~44.26%) derived from different sources is significantly lower than that (RE: 75.25%~140.87%) in slope length. (3) The discrepancy between different sources is enhanced in gully areas (RE of slope: 15.48%~56.63%; RE of slope length: 50.02%~130.79%), while being decreased in inter-gully areas (RE of slope: 21.28%~63.61%; RE of slope length 93.01%~192.51%). [Conclusion] It is feasible to obtain areal grading characters of slope or slope length and slope of specified locations using DEMs generated from Gaofen-7 satellite, while the results of slope length for specified locations are less reliable. In conclusion, the Gaofen-7 satellite has a great advantage in describing the spatial distribution of slope length and slope at the watershed scale, while being less capable of capturing slope length and slope at a specific site.

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    • Effects of snow cover change on the content of base ions and available silicon and aluminum of black soil in Northeast China

      Wang Zilong, Jiang Qiuxiang

      Abstract:

      Northeast China is the largest snow stabilization region in China. The change of snow deposition depth caused by climate warming may affect the frozen state of soil in the northeast black soil region in winter, and further change the physical and chemical environment of soil, so as to change the availability of soil base ions and available silicon and aluminum to crops in the growing season. In order to explore the seasonal variation characteristics of black soil base ions and available silicon and aluminum in northeast farmland under the change of snow depth in winter, the method of artificial snow depth control was adopted. By measuring the environmental factors (temperature and humidity, moisture content, pH value, total organic carbon), base ions, available silicon and active aluminum of the northeast farmland black soil in the snow removal group (SR), snow reduction group (SL), natural snow control group (C) and snow enhancement group (SA), the change process of the content of soil base ions and available silicon aluminum was analyzed. And their responses to soil environmental factors. The results showed that the decrease of snow depth changed the water and heat distribution of the black soil under seasonal snow cover, and the soil temperature of 0-30cm decreased significantly, while the average soil moisture content showed an increasing trend. With the decrease of HCO3- content caused by the decrease of snow cover depth, the average pH values of soil in each group changed by -0.06, -0.04, -0.02 and 0.01, respectively. The decrease of soil alkalescence increased the contents of exchangeable monovalent cations (Na+, K+), while decreased the contents of exchangeable and carbonate bivalent cations (Ca2+ and Mg2+). Carbonate divalent cation and exchange Na+ had positive and negative effects on TOC content, and the average total organic carbon (TOC) content increased by 0.87 g/kg, 1.09 g/kg, 1.32 g/kg and 1.48 g/kg with the decrease of snow cover depth, respectively. The interaction between base ions and soil pH and TOC reduces soil pH and organic matter content under the condition of reduced snow depth, resulting in the decrease of soil adsorption of available silicon, and promotes the conversion of low-active aluminum to high-active aluminum. Finally, the content of available silicon and aluminum humate (Al-HA) in soil is significantly reduced. The contents of exchange aluminum (Ex-Al), monomer hydroxy-Al (Hy-Al) and acid-soluble inorganic aluminum (Col-Al) increased significantly, and the base ions had a potential effect on the available silicon and aluminum indirectly through the interaction with TOC and pH.

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    • Labratory Simulation on Process of Soil and Water Leakage in Fissures in Karst Peak-cluster Depression

      LI Juan, LI Fahu

      Abstract:

      Control on soil and water leakage is the key to prevent rocky desertification in karst areas, but their loss mechanism and influence factors are still unclear. The effects of water pressure (0.3, 1.3, 2.3, and 5.5 m water head height), karst fissure width (0.25, 0.5, 0.75, and 1.0 cm), and soil aggregate size (0 – 1.0, 1.0 – 2.0, 2.0 – 5.0, and 0 – 5.0 mm) on the process of soil and water leakage in karst peak-cluster depression were studied through laboratory simulation tests. The results showed that whether the overlying soil layer is broken down or not determines the rate and amount of soil and water leakage. When overlying soil layer was not broken down, the rate of soil and water leakage decreased with time and gradually approached to be steady. Once the soil layer was broken down, water leakage rate increased sharply and then reached its steady state gradually, while soil leakage rate increased sharply to its peak value and then decreased to its steady one. The greater the water pressure was, the greater the soil and water leakage rates were, and the earlier the time that overlying soil layer was broken down and the rate peak of soil leakage occurred was. The greater the fissure width was, the greater the soil leakage rate was, the smaller the needed water pressure that the soil layer was broken down was, and the earlier the rate peak of soil leakage occurred was. The cumulative amounts of water and soil leakage increased with the increased water pressure or fissure width. The rate and accumulative amount of water leakage from soils that particle groups were missed were not affected significantly by soil aggregate size or fissure width, while that of soil leakage decreased with the increase of soil aggregate size. The cumulative soil leakage from small aggregate grounds decreased with the increase of fissure width but increased from large aggregate grounds accordingly. The greater the water pressure and the fissure width were or the smaller the soil aggregates size was, the more easily the soil layer was broken down. The soil layer with missing soil particle groups was more easily broken down than that with whole particle group. The rates and cumulative amounts of soil and water leakage after soil layer was broken down were significantly greater than that of unbroken soil layer. The research results provide a theoretical basis for revealing the mechanism of soil and water leakage and its control measure choice in karst regions.

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    • An Experimental Study on Effects of Rainfall, Inflow and Slope Gradient on Ephemeral Gully Slope Erosion in Chinese Mollisol Region

      GENG Huajie, ZHENG Fenli

      Abstract:

      Understanding effects of rainfall intensity, inflow rate and slope gradient on hillslope ephemeral gully erosion can provide a scientific basis for controlling soil erosion in the Chinese Mollisol region. This study designed two rainfall intensities (50 and 100 mm/h) and two slope gradients (3° and 7°), and five inflow rates under four combinations of two rainfall intensities and two slope gradients to analyze impacts of rainfall intensity, inflow rate, slope gradient and their interaction on slope soil erosion with ephemeral gully, and to quantify the contribution of ephemeral gully erosion to slope erosion. The results showed as follows: (1) The impact of slope gradient and inflow rate on slope soil erosion was greater than that of rainfall intensity. Under the five inflow rates, when the rainfall intensity increased from 50 mm/h to 100 mm/h, the slope erosion on the slopes of 3° and 7° increased by 52.3%-81.8% and 29.4%-88.4%, respectively; when the slope gradient increased from 3° to 7° , the slope erosion increased by 114.3%-395.5% and 130.0%-320.9%, respectively; when the inflow rate increased from 15 L/min to 75 L/min, the slope erosion increased by 4.6-13.5 times. The increase of inflow rate aggravated slope gradient influmce on slope erosion while weakened rainfall intesisty impacts on slope eroiosn. (2) The effects of rainfall intensity-inflow rate-slope gradient interactions, and inflow rate-slope gradient interactions on slope erosion were the largest impact, followed by the rainfall intensity-inflow rate interaction, and the interaction of rainfall intensity-slope gradient had the lowest impact. Ephemeral gully erosion occupied above 85% of total slope erosion at the different experimental treatments, which increased with inflow rate and slope gradient. (4) The slope erosion rate had positively significant correlations with the flow velocity, shear stress and stream power, while it had negatively significant correlation with the friction coefficient. Compared with the flow velocity and shear stress, the correlation between slope erosion rate and stream power was best.

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    • Effects of freeze-thaw cycles on soil structure under algal crust-covered conditions

      ZHONG Zhiqiang, MA Bo

      Abstract:

      [Objective] In order to study the effects of biological crustal cover and freeze-thaw on soil structure. [Methods] The effects of different freeze-thaw times, initial soil water content before freeze-thaw and biological crusting (algae crust) cover on soil structure characteristics were analyzed by using the indoor simulated freeze-thaw method. [Results] (1) The soil structure index (IGSS) obtained by orthogonal experiment was between 75.57~96.57, the signal-to-noise ratio (S/N) was between 37.55~39.70dB, and the optimal combination of factors determined by the Taguchi method was 15 freeze-thaw cycles, 15% initial water content, and 80% algal crust coverage, and the predicted results were IGSS=98.09, S/N=39.89dB. (2) IGSS was positively correlated with freeze-thaw times, initial water content and algal crusting coverage, and the main effects of each factor on soil structure index were initial water content> freeze-thaw times> algal crusting coverage. The contribution rates of each factor to the change of soil structure index were initial water content (52.17%)> freeze-thaw frequency (31.95%)> algae crusting coverage (2.12%). (3) The change of soil structure index comes from the loss of soil water and pore expansion during the freeze-thaw process, and algae crusting can slow down the loss of water during the freeze-thaw process, thereby slowing down the IGSS change. [Conclusion] In this study, orthogonal experiments were used to discuss the effect of algae crusting cover on soil structure under freeze-thaw conditions, and the results could provide a theoretical reference for the study of soil freeze-thaw process under complex conditions.

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    • Simulation effect analysis of RUSLE model on slope soil erosion restored by reclaimed vegetation in Loess Plateau

      LIAO Jun, JIAO Juying

      Abstract:

      In order to explore the effect of RUSLE model on soil erosion simulation on the slope of reclaimed vegetation on the Loess Plateau, this study is based on the monitoring data of rainfall production and sediment loss of 10 runoff plots in Fangta small watershed of Ansai District, Northern Shaanxi Province during 2016-2022. Through the transformation combination of different commonly used algorithms of various factors of RUSLE model, In this paper, the soil erosion of the restored slope under the combination of 144 factors was simulated, and Nash efficiency coefficient NSE and root mean square error RMSE were used to evaluate the effectiveness of the model. The results show that: The RUSLE model was used to simulate soil erosion with 144 factors. The NSE coefficient of the returned farmland vegetation restoration slope ranged from -38.47 to 0.19, and the root mean square error RMSE ranged from 1.92 to 12.65 t/(hm2·a). The simulation effect of RUSLE model on the returned farmland vegetation restoration slope was poor. The existing factor algorithms are difficult to adapt to the evaluation of soil loss on the slope of vegetation restoration, so it is necessary to further improve the factors of RUSLE model.

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    • Soil quality evaluation of different land use types and its obstacle factors in dip/anti-dip slopes in karst trough valley area

      shihailong, ganfengling

      Abstract:

      The Different rock strata inclinations can affect the soil flow/leakage and soil microorganisms on the erosion slope which results in the great difference of soil quality on the dip/anti-dip slope in the karst trough valley. In order to accurately evaluate the soil quality characteristics of dip/anti-dip slope erosion slope in Qingmuguan Karst trough valley, five typical? land use types (forest land, grassland, bare land, corn land, pepper land) were taken as the research objects. and there were 12 physical and chemical indexes as total data set (TDS). The principal component analysis method was used to combine the norm value to establish the minimum data set (MDS) of the evaluation index, and the soil quality in the study area was evaluated by membership function and nonlinear soil quality evaluation methods. The results showed as follows: 1) The minimum data set of soil quality evaluation indexes (MDS) in karst troughs valleys included capillary water capacity, capillary porosity and total phosphorus. 2) According to the nonlinear soil quality evaluation method, the soil quality of anti-dip slope (0.519) was better than that of dip slope (0.451). The soil quality of anti-dip slope forest land was the best (0.653), and that of pepper land was the worst (0.426). 3) The determination coefficient R2 of the nonlinear evaluation method is higher than the membership function for the dip slope and the anti-dip slope, so the non-linear scoring model is more suitable for the karst trough valley; 4) There were significant differences in soil quality barrier factors, and only total nitrogen was the common barrier factor. In conclusion, it is more beneficial to restore and improve soil quality by appropriately increasing grassland and forest cover in karst trough valley. The results of this study can provide basis for soil quality control and rational fertilization of slope erosion dip/anti-dip slope in karst trough valley according to local conditions.

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Editor in Chief:LIU Baoyuan
Founded in:1987
Governing Body:Chinese Academy of Sciences
Sponsor:Institute of Soil and Water Conservation, CAS & MWR;
Soil Science Society of China
Publisher:Editorial Department of Journal of Soil and Water Conservation
Phone:029-87012707
029-87010802
Address:Editorial Department of Journal of Soil and Water Conservation, No. 26 Xinong Road, Yangling District, Shaanxi Province, China
Postcode:712100
Email:stbcxb@nwsuaf.edu.cn
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