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Exploring the stoichiometric characteristics of understory plants' leaves and soils in different forest types in Mao'ershan can reveal the adaptation strategies of understory plants in Mao'ershan, and provide data support for forest management. In this paper, coniferous and broad-leaved mixed forest (ZK), evergreen broad-leaved secondary forest (CLC) and evergreen broad-leaved forest (CL) in Mao'ershan were selected as three forest types, the leaf stoichiometry of main plants in herb layer and shrub layer, and the soil stoichiometry under three forest types were measured and analyzed. The results were as follows: (1) There was no significant difference in leaf C and N contents between herb layer and shrub layer, but P and K contents in herb layer were extremely significantly higher than that in shrub layer, and N P was significantly lower than that in shrub layer. Plants in herb layer was more likely to be restricted by N, plants in shrub layer was more likely to be restricted by P and the utilization efficiency of N and P were higher. There was no significant difference in leaf stoichiometry of plants in shrub layer among different forest types, but there were significant differences in leaf N content, CN, C P of plants in herb layer among different forest types. Plants in herb layer of ZK had higher nutrient use efficiency. (2) The soil C and N contents of the three forest types showed that CL > CLC > ZK, and there were extremely significant differences among the three forest types. The soil P content of ZK were the highest, while that of C: P and N P were the lowest. (3) Soil in ZK significantly affected some leaf stoichiometry of plants in herb layer and shrub layer, while the other two forest types had no significant effect on underforest plants. To sum up, there are significant or extremely significant differences in soil stoichiometry among different forest types in Mao'ershan. The nutrient requirements and environmental adaptation strategies of plants in herb layer and shrub layer are different. The soil of ZK has a strong influence on the leaf stoichiometry of understory plants, and the soil with low decomposition efficiency of organic matter in this forest type, and the soil is limited by N due to the low decomposition efficiency of organic matter, so the management of N in the mixed forest should be strengthened. [ABSTRACT FROM AUTHOR]

In paddy wetland ecosystems,soil phosphorus adsorption and release characteristics play an important role in crop growth and environmental protection. CiteSpace software was used to visualize and econometrically analyze the research literature on phosphorus adsorption and release in CNKI database from 1992 to 2022,summarized the input and output of phosphorus in paddy wetlands,sorted out the development context of phosphorus adsorption and release research,used price theory to calculate the core author group,and retrospectively explored the main research hotspots and applications of phosphorus adsorption and release in paddy wetlands. The results showed that there were 1 130 articles on phosphorus adsorption and release from 1992 to 2022,and the overall trend of publication volume was rising in waves,and a large number of scholars were paying more and more attention to this field. An analysis of core researchers found that the research team centered on Lin Weijian and Zhan Yanhui of Shanghai Ocean University ranked first in the number of articles,but there was little cooperation between different authors. After cluster analysis of keywords,the research content of phosphorus adsorption and release could be divided into four categories, mainly involving four aspects of phosphorus morphological distribution,influencing factors of phosphorus adsorption and release,evaluation of soil adsorption and phosphorus release capacity,and the use of mathematical models to explore the adsorption and release process of phosphorus. The migration and transformation of phosphorus in paddy wetlands and the environmental risk of phosphorus loss had become research hotspots in this field,and the use of covering technology and biochar were future research trends and would become the key research direction of a large number of scholars. In general,the research on the adsorption and release of phosphorus had received more and more attention,the number of papers and research directions continued to rise and spread,and the application research in paddy wetlands was not extensive enough,and further cooperation between research institutions and scholars should be continuously strengthened,and new technologies should be used to promote the utilization of agricultural resources in rice wetlands and promote the sustainable development of the ecological environment. [ABSTRACT FROM AUTHOR]

Greenhouse vegetable production is currently one of the main agricultural planting methods. The heavy metal pollution is the relatively prominent problem in the greenhouse vegetable field which is under a semi-closed state with high temperature, high humidity and high fertilizer input. Due to the complexity of soil environment, and the diversity of sources and the specificity of distribution of heavy metal pollution, a comprehensive and detailed system for the source apportionment of heavy metals in soils has not been established. Little is reported in literature on the source apportionment of heavy metal pollution in greenhouse vegetable fields. In this paper, the application of source apportionment of heavy metals in greenhouse vegetable fields was reviewed based on the related literature. In view of the limited application of quantitative source apportionment of heavy metals in greenhouse vegetable fields, several suitable methods were recommended and their advantages and disadvantages were summarized. Meantime, the prospect of the research on the source apportionment methods of heavy metals in greenhouse vegetable fields was put forward, so as to provide the technical support to solve the problem of heavy metal pollution in greenhouse vegetable fields from the source. [ABSTRACT FROM AUTHOR]

Mulch film mulching cultivation technology not only increases agricultural production and income, but also causes serious pollution problems because of the long-term use of polyolefin mulch film and low recovery rates. In areas with serious mulch film residue, the soil structure is seriously damaged, the quality of cultivated land is reduced, agricultural operations are blocked, and crop emergence, nutrient absorption and root growth and development are restricted. Biodegradable mulch film can be degraded by microorganisms such as bacteria, fungi and actinomycetes in the natural environment, and finally decomposed into CO2 and H2O, which not only has no pollution to soil but also promotes the growth and development of crops, and has become one of the effective ways to solve the problem of white pollution. With the deepening of the research on biodegradable mulch film, people found that biodegradable mulch film has different effects on soil environment and crop yield, and these effects are quite different in different regions and crops. It is not possible to directly draw the conclusion that biodegradable mulch film is better than PE mulch film through one or several experiments. In this paper, the effects of biodegradable mulch film on soil environment, crop growth and yield in recent years were summarized, and the experimental effects of biodegradable mulch film (BM) and mulch mulch film (PE) were compared, and their advantages and disadvantages were analyzed, and suggestions were put forward to improve the performance of biodegradable mulch film, so as to continuously improve the performance of biodegradable mulch film and realize the sustainable development of agricultural science and technology. Summary and analysis show that: (1) Biodegradable mulch film can increase soil temperature and humidity, meet the needs of crops in the early stage of growth, accelerate the emergence of seedlings, shorten the growth cycle, and have beneficial effects on soil organic matter, available nitrogen and soil enzyme activity, and improve soil nutrient content. In terms of microorganisms, biodegradable mulch film can promote the growth of soil microbial content and soil respiration rate. At the same time, biodegradable mulch film has better weed control ability than PE mulch film, among which black biodegradable mulch film has the best effect, which can effectively reduce the number of weeds in the field and ensure the supply of nutrients needed by crops. (2) In terms of crops, biodegradable mulch film can promote corn growth, shorten the growth period and increase the yield in the early and middle stages of corn growth. There was no significant difference between the yield of cotton seed cotton covered with biodegradable mulch film and PE mulch film, and the yield of cotton seed cotton covered with mulch film is significantly higher than that of bare land. The potato treated with biodegradable mulch film germinated faster in the early growth stage because of the increase of soil temperature, which significantly shortened the growth cycle and brought it to market earlier, and significantly increased the yield compared with PE mulch film and bare land, among which the black biodegradable mulch film had the most obvious effect. For millet crops, there was no significant difference in yield between the treatment with biodegradable mulch film and the treatment with PE mulch film, and the yield of the treatment with mulch film was significantly improved compared with the treatment with bare land. For vegetable crops such as tomato, eggplant and beet with short growth cycle, biodegradable mulch film can play the role of heat preservation and moisture increase for a long time, and promote the rapid growth of crops. The final yield is not significantly different from that of PE mulch film mulching treatment, even slightly improved, and significantly improved compared with bare land treatment. (3) Put forward the influence of different components of biodegradable mulch film on soil and crops, controllable degradation and cost problems, such as the difficult control of degradation speed, environmental problems caused by incomplete degradation of biodegradable mulch film, low technical maturity and high price, and put forward suggestions for future research and development, so as to modify and innovate biodegradable raw materials, reduce costs and regulate the degradation mechanism of biodegradable mulch film. Strengthen the research on raw materials, formula and production technology of biodegradable mulch film, and develop new biodegradable mulch film with high performance and multifunction, which can meet the regional applicability and crop applicability at the same time, and lay a theoretical foundation for the popularization and application of biodegradable mulch film to more regions and more crop varieties. [ABSTRACT FROM AUTHOR]

This paper combed the technical principle, pretreatment, sample transfer and detection process of quantum cascade laser imaging for analyzing microplastics in soil samples, and summarized and compared the technical application and limitation analysis of physical analysis and chemical analysis (microscope analysis, spectral analysis, mass spectrometry analysis), in eluded the technical process of the main test method, the applicable field, and the advantages and disadvantages. On the basis of the above analysis, the applicability and advancement of the quantum cascade laser imaging in the detection of microplastics in soil samples were summarized・ An important role in the research of microplastics in soil environment and the prevention and control of pollution were played in this method. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to reveal the mechanism of action of soil bacterial community environment in woodland under different restoration patterns. [Method] Using high-throughput sequencing technology, we analyzed the relationship between soil physicochemical properties and dominant bacterial communities through the composition and diversity of soil bacterial communities in southern Aquilaria sinensis, Acacia mangium forests and natural secondary woodlands. [Result] (i) In the taxonomic study of soil bacteria in different forest stands, there were 44, 32 and 35 phyla of soil bacteria in the Aquilaria sinensis, Acacia mangium and secondary forest, respectively.The composition of soil bacteria in the three forest stands was relatively similar, and the dominant bacterial groups were Proteobacteria and Acidobacteria, and the communities with relative abundance ＞1% were all Actinobacteria, Verrucomicrobia and Planctomycetes. (ii) In the α-diversity analysis of soil bacteria in different forest stands, the highest Chao1 index of secondary forest soil indicated the highest bacterial community in this soil, and the highest Shannon index of soil sedum forest soil indicated high bacterial diversity in this soil. (iii) In the β-diversity analysis of soil bacteria in different forest stands, the soil bacterial community structure of soil sedum forest and Acacia mazanensis forest was differential, while the secondary forest had similar soil bacterial structure to the former two. (iv) In the RDA redundancy analysis of soils in different stands, Phytophthora variegata and Phytophthora floxa were significantly and positively correlated with fast-acting potassium, effective phosphorus and total phosphorus. Acidobacteria were negatively and significantly correlated with soil pH, effective phosphorus and fast-acting potassium. [Conclusion] The results reveal the structural variability and diversity of soil bacterial community composition in three different forest stands in Shenzhen, and provide a theoretical basis for further exploring whether the artificial restoration model is superior to natural forests. [ABSTRACT FROM AUTHOR]

The soil spectral characteristics are affected by soil particle size, water, and other factors, resulting in different spectral characteristics of soil in different regions due to different climate and geographical conditions. The soil composition prediction model established by using near-infrared spectroscopy technology often has its uniqueness. In this paper, in order to provide reference for the subsequent development of a soil nitrogen content rapid analyzer based on near-infrared spectroscopy technology, the soil nitrogen content was predicted by visible and near-infrared spectroscopy taking soil in Shanxi maize field as the research object. 120 soil samples were collected from the maize test field of Shanxi Agricultural University, and the total nitrogen content was determined and the visible and near-infrared spectroscopy was collected. The calibration set and prediction set were divided by the spectral physicochemical value co-occurrence distance(SPXY) algorithm at a ratio of 2:1. The effects of soil nitrogen content prediction models were analyzed, the models were established by combination with three modeling methods including partial least squares(PLS), support vector machine(SVM), and principal component regression(PCR), using six preprocessing methods including smoothing, standard state transformation, baseline correction, de trend, normalize, and multiple scattering correction(MSC), and the best prediction model was selected. The results showed that among the 21 prediction models established, the prediction model established by smoothing pre-processing method and PLS had the best effect, with the orientation coefficient(R2 ) of 0.907 and the prediction root mean square error(RMSEP) of 0.086. This prediction model could effectively predict the soil nitrogen content of maize fields in Shanxi province. [ABSTRACT FROM AUTHOR]

Based on the bibliometrics analysis, this paper firstly identifies that the research focus of humic acid-based material immobilization field is on immobilization remediation effect and remediation mechanism.Based on the two research focuses identified, the heavy metals in soil were classified into those in the form of cations（e.g.Cd, Pb, Hg, etc.) and those in the form of oxygen anions（e.g.As and Cr),and the immobilization effects and immobilization mechanisms of humic acid and humic acid-based materials on soil heavy metals were systematically reviewed.Humic acid and humic acid-based materials have highly effective to immobilize soil heavy metals, and their immobilization mechanisms mainly include complexation, ion exchange, electrostatic interaction, redox and co-precipitation with introduced modified materials.This review further points out the shortcomings of humic acid-based materials in immobilization remediation technology in terms of practical applications and provides an outlook on future research directions, in order to provide scientific references for in situ immobilization remediation of heavy metal contaminated soils. [ABSTRACT FROM AUTHOR]

This paper briefly describes the mechanism of phytoremediation, the advantages and the application of ornamental woody plants. Based on the article analysis, it is found that the concept of hyper accumulation has been emphasized too much in the study of phytoremediation, the usage of herbal hyper-accumulator plants can not last for a long period in field level as the economic benefits is fairly low. Thus, the outstand advantages of ornamental woody plants are outlined, such as more biomass, casier management, pollution remediation and improvement of cultural environments. Relevant studies of remediation by ornamental woody plants are focused on variety, absorption characteristics and resistance assessment. Conclusion: ornamental woody plants show strong resistance and significant ability of metal adsorption. Ornamental woody plants have great potential in remediation of heavy metal comminuted soil. In the future, the theory of resistance and absorption should be strengthened. Other studies are also important, such as expanding the types of ornamental woody remediation plants and screening out more economic and effective plants. As a result, more and more ornamental plants will be put into practice in remediation. [ABSTRACT FROM AUTHOR]

Fluoride is one of the important trace elements of human life and health. A proper amount of fluoride is beneficial to health. Excessive intake of fluoride will lead to dental fluorosis, bone fluorosis and urolithiasis, and serious excessive intake will affect the human central nervous system, endocrine hormone levels and reproductive system. The same lack of fluorine can also cause dental caries, Kaschin - beck disease signs and osteoporosis symptoms and cause hematopoietic dysfunction. Due to the chemical characteristics of fluorine, the forms of fluorine in the natural environment are very complex, and the transformation between different forms needs further study. How to quickly and accurately determine the content of fluorine in soil, rocks and minerals is of great significance for evaluating regional geochemical behavior and preventing fluorine-related diseases in humans. In this paper, the research progress of fluorine analysis and testing technology in soil, rocks and minerals in recent years is described. The methods, reagents and processes of sample pretreatment are summarized. The matrix correction, interference control, performance and application status of d ifferent testing methods are reviewed. In order to ensure the accuracy and reliability of the test results, it is necessary to eliminate the interference of metal cation, matrix effect and particle size validity, select the appropriate pretreatment and detection technology, reduce the detection limit, and constantly improve the accuracy and precision of the test. At present, the commonly used pretreatment methods mainly include pressed powder pellet, fusion, steam distillation, high temperature combustion hydrolysis, alkali fusion and acid dissolution. Among them, the pressed powder pellet method is simple, employs nondestructive analysis, has high sample preparation efficiency, and can meet the requirements of pretreatment of fluorine in large quantities of soil. The fusion method can effectively reduce the particle size effect and mineral effect, but different matrix samples need to use different oxidants, the preparation process is complicated, and requires high experience of the sample maker. Steam distillation and high temperature combustion hydrolysis are mainly used in rock sample treatment. The interference of metal ions can be effectively reduced by steam distillation or high temperature combustion hydrolysis. The test results of the samples treated by the alkali fusion method are stable and widely used, but there is metal ion interference, which leads to low fluorine test results. The acid dissolution method is used mainly for the decomposition of some specific ore samples, such as phosphate ore, and is rarely used at present. The commonly used determination methods include the ion selective electrode method, ion chromatography, XRF method, spectrophotometry, colorimetric method and liquid chromatography. Among them, the ion selective electrode method is mature and widely used because of its high accuracy and good stability. The detection limit of ion chromatography is low, but the test efficiency is low. X-ray fluorescence spectrometry uses lossless injection, simple environmental protection and can measure multiple elements at the same time. The colorimetric method is not accurate enough, the stability of the method is poor, the analysis steps are more complicated, and it is not suitable for the analysis of daily samples. Liquid chromatography is rarely used at present because of the expensive pretreatment equipment. At present,the alkali fusion method (accounting for 26%) is widely used as the most important pretreatment means, but it has many shortcomings, such as large reagent consumption, long process, complicated steps and cationic interference. Further research and practice are needed to optimize testing techniques and methods. The high temperature combustion hydrolysis method (accounting for 13%) and steam distillation method (accounting for 18%) can reduce cationic interference, but their cumbersome steps and special expensive equipment are currently used less. The ion selective electrode method accounted for more than one third of the test methods. Currently, the pre- treatment method using alkali fusion - ion selective electrode method is one of the most effective test technologies for the determination of fluorine content in soil, rocks and minerals. Pressed powder pellet method (accounting for 17%) has potential research value because of its unique nondestructive injection, simple, fast and environmental protection, and the matching XRF method ( accounting for 29%) can realize multi - element combined measurement, which has significant advantages in stability and precision. The future research direction of fluorine determination by X-ray fluorescence spectrometry will be how to reduce the detection limit of the method and eliminate the particle size effect and mineral effect. Other analysis and testing techniques are not recommended because of cumbersome procedures, expensive pre-treatment equipment, only certain types of samples can be processed, and limitations of testing methods. As fluorine is a light element and its occurrence forms are complex and diverse, it is necessary to select appropriate analysis and testing techniques according to the characteristics of sample types. The main research directions of fluorine analysis and testing technology in soil, rocks and minerals and pretreatment methods are focused on non-destructive analysis of samples, safety and environmental protection, rapid and other aspects, and the main research directions of testing technology are focused on the establishment of multi-element simultaneous determination. In conclusion, the determination of fluorine in soil, rocks and minerals by pressed powder pelletX-ray fluorescence spectrometry has important research value. [ABSTRACT FROM AUTHOR]

Steel slag particles with high hardness, high modulus and certain cementitious activity can be used as solidified soil material. The influence of steel slag on soil mechanics, stability and solidification mechanism are not clear. In this paper, the effects of steel slag content and steel slag particle size on soil California Bearing Ratio（CBR） value, water absorption, expansion rate and compressive strength were studied. By calculating the comprehensive, physical and chemical effects index of steel slag on soil modification, the solidification mechanism of steel slag on soil was described. In addition, XRD, IR and SEM-EDS were used to reveal the mechanism of steel slag on soil chemical modification. The results show that steel slag have significant physical and chemical modification effects on soil, and the mechanical and stability properties of soil increase with the increase of steel slag content, while decrease with the increase of steel slag particle size. When steel slag content is 8%, CBR value and 4 d unconfined compressive strength（UCS） increase by 1014.4% and 180.0%, respectively, water absorption and expansion rate decrease by 53.0% and 45.4%, respectively, compare with that of plain soil. The decoupling analysis shows that the physical modification effect of steel slag is much weaker than the chemical modification effect, and the chemical modification effect plays a dominant role in the comprehensive modification effect of steel slag. The 4 d contribution weight of 0-0.6 mm steel slag to chemical modification is 72.2%, while the contribution weight of physical modification is only 27.8%. In addition, with the increase of age, the contribution weight of chemical modification is further increased. At 28 d and 90 d, the contribution weights of 0-0.6 mm steel slag to chemical modification increase to 78.7% and 86.3%, respectively. Microcosmic test results show that hydration and ion exchange reactions occurred after steel slag is added to soil. The C—S—H peak can be found in the XRD test results, and the enhanced vibration peak of the Al3+ cation coordination can be observed in the IR test results. From SEM test results, it can be seen that the floccule C—S—H gelatinous material has significantly fewer pores than plain soil, and its structure becomes more dense, which is consistent with the macroscopic mechanical properties. [ABSTRACT FROM AUTHOR]

[Objective] The present paper aimed to take the open-pit coal mining area in southern Karamari mountains as an example, the contents, enrichment characteristics and spatial distribution of heavy metals in typical desert plant Reaummuria soongorica（Rs）and surrounding soil were analyzed. The pollution status of six heavy metals, zinc, copper, chromium, lead, mercury and arsenic (Zn, Cu, Cr, Pb, Hg, As) was evaluated and their sources were explored. [Method] Mathematical statistics and GIS methods were used to analyze the enrichment characteristics and spatial distribution of heavy metals in bipachai, analyze the pollution sources and evaluate the potential ecological risk. [Result] The over-standard rates of Cr, Pb and As in soil samples were more than 70%, and the average values exceeded the background values of Changji. The over-standard rates of Hg in Rs samples were 23.08%. The enrichment coefficient (3.658) of Hg in Rs was much higher than that of other elements, indicating that Rs has a strong tolerance to Hg. Except for Pb, the retention rate of other elements was positive, indicating that there was a certain tolerance in the root of Rs. Zinc and copper mainly came from crustal sources, while other elements were affected by both human and natural factors, especially Hg, which was heavily affected by disturbance in mining area and seriously polluted. Potential ecological hazard assessment results showed that in soil and plant, Zn, Cu, Cr, Pb, As five elements were relatively light pollution, Hg pollution was more serious. The distribution of Cu, Cr and As in Rs was similar, which might come from same sources. The enrichment ability of Rs to As was related to the content of As in soil. [Conclusion] The content of elements exceeding the standard in the soil of the study area was low in Pipa. At the same time, Pipa had a certain tolerance and can be used as a dominant species for ecological restoration. [ABSTRACT FROM AUTHOR]

Isitu passivation repair technology for heavy metals is a promising processing technology. This technology mainly adds exogenous remediation agents to the contaminated soil, and undergoes a series of reactions such as adsorption, ion exchange, precipitation, oxidation-reduction and other heavy metal ions to convert heavy metals into a more stable form and fix them in the soil, thereby preventing heavy metals from passing through plant roots migrate to the upper part of the ground to achieve the purpose of repairing the soil. This paper systematically expounds the effect and repair mechanism of passivation technology, deeply analyzes the types of passivation materials, and further puts forward the problems to be solved in passivation repair technology from the practical application, and prospects for future research directions. [ABSTRACT FROM AUTHOR]

Combined with the existing research, the research progress of biochar remediation of heavy metal pollution is reviewed. This paper focuses on the mechanism of biochar immobilization of heavy metals in soil, the effect of biochar on the absorption of heavy metals by plants, the research results of the application of biochar in field engineering, and the risks and shortcomings o£ biochar as a soil improver. Finally, it is hoped that on the premise of meeting safe production, the popularization of biochar should be promoted in agricultural production, rather than limited to scientific research. Start the life cycle assessment of biochar and establish a biochar life cycle database to provide a comprehensive and effective scientific basis for the future use of biochar. [ABSTRACT FROM AUTHOR]

Excessive anthropogenic emissions of greenhouse gas have led to global climate change in recently years. Methane is an important greenhouse gas after carbon dioxide. Methane emissions increase with the global temperature, which further intensifies global warming. Soil is a huge source and sink of methane, and methanotrophic bacteria play a key role in reducing methane emissions. Exploring the effect of temperature on soil methane-oxidizing ability has been a research hotspot in recent years. This paper reviewed the effects of temperature on soil methane oxidation and methanotrophic bacteria; analyzes and compares the soil methane oxidation process and methanotrophic bacteria in various ecosystems at different temperatures, and the growth temperature range of methanotrophic bacteria strains. The results showed that various ecosystems have different temperature ranges for methane oxidation; the rate of methane oxidation increases with increasing temperature in their particular temperature ranges. When the cultivation temperature is closer to the in-situ temperature, the methane oxidation response will be faster. Similar to the effect of temperature on methane oxidation, the diversity and abundance of methanotrophic bacteria also increase with increasing temperature and are closely related to the magnitude of temperature increase and the adaptation temperature of dominant bacteria. Type II methanotrophic bacteria in the soil are more sensitive to temperature. As the temperature rises, the abundance of type II methanotrophs increases. Therefore, temperature affects the abundance and community structure of methanotrophs, thereby affecting the rate of methane oxidation and methane emissions. However, whether temperature can only change the methane oxidation capacity of the soil by regulating the replacement of dominant bacteria is still unconfirmed. This review discussed the response of methane oxidation to temperature and its microbial mechanism, in order to provides a comprehensive analysis for methane oxidation capacity under the context of future climate change. [ABSTRACT FROM AUTHOR]

Solidification and stabilization (S/S) is one of the primary technologies for the treatment of heavy metals in soil. It is particularly important to strengthen the concept of solidification and stabilization materials in the research and development of materials. The mechanisms of solidification and stabilization materials on soil heavy metals include precipitation, adsorption, coordination, organic complexation, and redox reactions. This paper mainly focuses on the systematic study of materials in soil heavy metal solidification and stabilization, proposes research & development methods for soil heavy metal solidification and stabilization, including screening and comparison, optimization and combination, surface modification, surface loading, and bridging composite methods. The basic research on the application of solidification materials includes five aspects of the framework, solidification and stabilization materials-heavy metals-water bodies, solidification and stabilization materials-soil-heavy metals, solidification and stabilization materials-soil-plant-heavy metals, solidification and stabilization materials-field-crop-heavy metals, and the evaluation of environmental safety and application effect on heavy metal treatment. For each aspect, the main content and key linked points of the research are explained. This holds importance for promoting the study of materials in soil heavy metal solidification and stabilization, and strengthening the application based on this process. [ABSTRACT FROM AUTHOR]

In order to explore the forest hydrological ecological function of Zhongtiao Mountain, the Phoenix Valley Forest Park in Yuncheng city is taken as the research object, which is located in the hinterland of Zhongtiao Mountain. In this paper, four kinds of forest types were selected in this area, including Celtis sinensis and Zelkova serrata broad-leaved mixed forest, Crataegus pinnatifida forest, Koelreuteria paniculata forest, Pinus tabuliformis and Celtis sinensi coniferous and broad-leaved mixed forest. The hydrological properties of litter layer and soil layer were measured and their differences were analyzed. The results showed that the total litter accumulation of the four forest types ranged from 10.75 to 15.84 t/hm², and the order from large to small was Pinus tabuliformis and Celtis sinensi coniferous and broad-leaved mixed forest, Koelreuteria paniculata forest, Celtis sinensis and Zelkova serrata broad-leaved mixed forest, Crataegus pinnatifida forest. The range of maximum water holding capacity of litter accumulation was 40.39 to 49.92 t/hm², and the water holding capacity of litter layer in Celtis sinensis and Zelkova serrata broad-leaved mixed forest was better than that in coniferous and broad-leaved mixed forest and pure forest. The soil bulk density ranged from 0.55 to 0.88 g/cm³ of different forest types, and the non-capillary porosity ranged from 3.07% to 15.56%, the soil bulk density was the lowest and soil non-capillary porosity was the highest in Pinus tabuliformis and Celtis sinensi coniferous and broadleaved mixed forest, indicating that the soil permeability was good. The soil capillary porosity, total porosity, capillary water holding capacity and maximum water holding capacity of Celtis sinensis and Zelkova serrata broadleaved mixed forest were the largest, which showed good water conservation performance. The comprehensive analysis showed that the hydrological performance of the Celtis sinensis and Zelkova serrata broad-leaved mixed forest was the best, and the decomposition of the litter layer was an important factor affecting the water conservation function of the forest area. [ABSTRACT FROM AUTHOR]

Purple soil which riches in mineral nutrients and is the main farming soil in Southwest China. Purple soil color images collected by machine vision have complex background, including crops, weeds, scattered small soil blocks and surface soil because of its stochastic field scenes. In order to avoid the interference of background on further processing and recognition of purple soil with machine vision, it is a primary task to segment the purple subsoil region from its background adaptively. Clustering algorithm has achieved good results in image segmentation and is widely applied. However, the selection of parameters of some classical clustering algorithms are sensitive, which need to be manually set and cannot satisfy to the adaptive segmentation of purple soil. Thus, aiming at the problem of adaptive segmentation, a segmentation methool of purple soil color image based on adaptive density peaks clustering was proposed in this paper. The specific segmentation algorithm was as follows: firstly, in order to calculate the density peaks conveniently and increase the separability between soil region and its background, a color to gray transformation method was carried out. The entropy-based similarity matrix was constructed, then the optimization model based on maximizing the between-class variance and minimizing the withinclass variance criterion was established with the similarity matrix. The optimization model was solved to obtain the gray matrix, which enhanced the separability of the gray value for clustering. Secondly, in the light of the shortcomings of density peaks algorithm, the density formula was improved and a measure was designed to determine the clustering centers adaptively, which realized the adaptive segmentation of purple soil region with the clustering algorithm based on the density peaks clustering framework, and improved the initial segmentation accuracy. Finally, post-processing algorithms of boundary extraction and region filling were designed to remove both the discrete small soil blocks in the background area and the internal voids in the soil area of the image obtained by initial segmentation. Therefore, the purple soil region image could be completely obtained and the segmentation accuracy of soil region was improved. From purple soil color images collected by machine vision in the field, 60 images with normal illumination, no surface soil and no shadows around the subsoil were randomly selected as normal test images and divided into 20 groups.we picked out randomly 60 images with the characteristics of normal illumination, then another 60 images were randomly selected as robustness test images, which were characterized by scattered subsoil and some shadows around the topsoil. These images were divided into 20 groups. The results of contrast test showed that the proposed method could automatically segment the purple soil color images of normal test and robustness test. For 60 normal test images, average segmentation accuracy of the proposed algorithm were 93.45%, which were 11.54, 7.96, 3.16 and 0.85 percentage points higher than that of FRFCM (fast and robust fuzzy C-Means) algorithm, H-threshold algorithm, DPC (density peaks clustering) algorithm and DFDPC (data field based density peaks clustering) algorithm, respectively. For 60 robustness test images, average segmentation accuracy of the proposed algorithm were 87.40%, which were 11.75, 5.2, 12.47 and 3.09 percentage points higher than that of FRFCM algorithm, H-threshold algorithm, DPC algorithm and DFDPC algorithm, respectively. The results proved that the proposed algorithm in this paper was superior to the other four comparison algorithms. Furthermore, boundary extraction algorithm and region filling algorithm further improved the average segmentation accuracy of soil region, in the post-processing stage. In the final exact segmentation results, average segmentation accuracy of normal test images were 96.30%, with average time-consuming of 0.36 s，and average segmentation accuracy of robustness test images was 91.63%, with average time-consuming of 0.35 s. In conclusion, the proposed algorithm was effective, and it can provide reference for the segmentation and extraction of purple soil region from the computer vision image. [ABSTRACT FROM AUTHOR]

Accurate and effective drought monitoring using remote sensing technology is essential for regional and global drought warning and forecasting. Especially, soil moisture (SM) is one of the key potential factors affecting agricultural drought. At present, most studies ignore the fact that soil moisture is a complex nonlinear coupling system，the research only using visible light, near infrared, short-wave infrared, thermal infrared and other remote sensing drought index has certain limitations in SM inversion. A new method of retrieving farmland SM of winter wheat at returning green stage based on MODIS and radial basis function neural network (RBFNN) is presented in this paper. Firstly, the adaptability of various MODIS-derived drought indices is analyzed in the period of seedling establishment of winter wheat, including soil water content, crop morphological change in water requirement, crop canopy water content and temperature and other parameters. Secondly, the correlation between the original remote sensing drought indices and the soil relative humidity 10 cm soil layer was analyzed. A comprehensive evaluation set of apparent thermal inertia (ATI), vegetation supply water index (VSWI), enhanced vegetation index (EVI), normalized difference infrared index band7 (NDIIB7), normalized multi-band drought index (NMDI) and temperature condition index (TCI) are selected to invert soil moisture of farmland. Finally, combining MODIS remote sensing drought index with RBFNN, the SM of farmland was retrieved synergistically, and the retrieved results were compared with those of BP-NN and linear regression (LR) models. The experimental study is conducted in Henan province of China, MODIS reflectance products (MOD09A1) and temperature products (MOD11A2) at returning green stage of winter wheat from 2001 to 2012 were used to extract remote sensing drought indices, and the global land cover product of MODIS (MCD12Q1) is selected to obtain cropland distributions. Soil moisture data is derived from the “China crop growth and development and farmland soil moisture ten-day dataset”, which contains the soil relative humidity of 10 and 20 cm soil layer observed every 10 days by 17 soil moisture stations. The results show that the average accuracy of SM inversion model using RBFNN and multiple drought indices is 93.27%, which is increased by 2.92 and 9.97 percentage points compared with BP-NN and LR model, respectively. Most of the data points of the three models are concentrated around the 1:1 line, which indicate that there is a good correlation between the predicted value and the measured value. Compared with BP-NN model and LR model, the deviation between predicted value of RBFNN model and the 1:1 line is the smallest, the higher the regression correlation coefficient is, the higher the determination coefficient is. SM is significantly correlated with ATI, NDIIB7 and VSWI in the early growth stage of winter wheat. Multi-band remote sensing drought monitoring indices can comprehensively reflect the changes of crop physiology and morphology under soil water stress, and also determine the retrieval accuracy of the humidity model simultaneously. In this paper, only winter wheat in returning green stage is selected as the research object, and the comprehensive evaluation index set selected is not suitable for SM inversion of other growth stages of winter wheat, the adaptability of different remote sensing drought indices in different growth stages needs further experimental study. The study provides a new case for regional SM inversion from remote sensing-based drought monitoring indices and neural network. [ABSTRACT FROM AUTHOR]

[Objectives] This paper was aimed to study the remediation effects of phosphate-solubilizing fungi and bone char in different soils. [Methods] Three different types of lead-contaminated soils (neutral yellow brown soil, alkaline sand soil and acidic red soil)were mixed with the bone char sintered at different temperatures. We measured the contents of phosphorus and lead, and the remediation differences of different soils. The Pb bioavailability of lead-contaminated soil was then determined by planting non-heading Chinese cabbage. The application potential of compound remediation materials was confirmed by adding compound remediation agents to the soil with the best remediation effect. [Results] The bone char had the best effect of promoting the release of phosphorus in yellow brown soil, and the available phosphorus content was 64 times higher than that of the control, showing a high potential of lead remediation. The pH of yellow brown soil was neutral, and the available P in the soil would not be fixed by Ca, Fe, Al, etc., thus increasing the probability of its reaction with Pb. When bone char was solely used, the material treated at 200-300 ℃ had qualified remediation effect. We planted non-heading Chinese cabbage to verify the bioavailability of lead in yellow brown soil after bone char application. It was observed that addition of a certain proportion of bone char to yellow brown soil (the initial mass ratio of bone char to lead was over 0.5:1) could not only increase the absorption of phosphorus by 2.0 to 3.5 times, but also reduce the absorption of lead by non-heading Chinese cabbage(content of lead in pakchoi leaves was reduced by 70% to 80% compared with blank treatment). A composite of bone char and Aspergillus niger was further applied to yellow brown soil, and the effective lead was reduced to 14.36 mg·kg-1. In particular, the growth of the A. niger proved the remediation potential of the composite. [Conclusions] The composite of bone char and A. niger was suitable for lead remediation in neutral soils, and the suitable heating temperature for preparing bone char was 200-300 ℃. [ABSTRACT FROM AUTHOR]

[Objectives]This paper aimed to evaluate the validity of pesticides application strategy in rice, and analyse the risk of dietary exposure and ecological impact. [Methods] This study implemented long-term investigation on usage and residual details of pesticides using for pest control in single-season and double-season rice of Jiangsu and Jiangxi provinces. Investigation of pesticides residues in rice and soil had been conducted in the period of tillering, heading and harvesting stage, and the results had been compared between the pesticide reduction strategies adopted area and the regular integrated pest management (IPM) adopted area. Acute and chronic dietary exposed risk and ecological impact risks had been evaluated by using the dietary exposure risk assessment model and the ecology relative risk model (EcoRR). [Results] The results revealed that.4 of total 51 pesticides used in rice for pest control, had been found in the harvest brown rice. Pymetrozine and hexaconazole were the most frequently found pesticides in all rice samples with the frequency up to 93.00% and 28.75%, followed by 14.29% and 7.14% for chlorpyrifos and pentazolidol, respectively. However, the risk assessment of acute and chronic toxicity that may be caused by these 4 pesticides through dietary exposure, was finalized to be negligible for all populations divided by age. Adopting pesticide reduction strategies could further low the risk of dietary exposure. As for the soil sampled from the period of tillering, heading, and harvesting stages of rice, 13 different kinds of pesticides were found, tricy clazole, hexaconazole and propiconazole with 100% detection rates in particular. It could be explained by the long half-life periods of these pesticides and the remains of previous residue. The ecological risk assessment showed that the reduction use of pesticides could decrease the ecological risks significantly, even down to low level from medium level risk. It was found that the most effective effort of reducing the ecological impact was to decrease the use of pymetrozine, as this pesticide played a key role to the contribution of ecological risks in the period of tillering, heading, and harvesting ( 54.16% -83.68%, 19.07%-84.39%, and 0.00%-82.32% respec tively). Secondly, the use of pretilachlor at tillering stage, difenoconazole at the heading stage and propiconazole at the harvest stage was considered to be alternative key elements for the cause of ecological risk, with contributions of the risk ratios of 0.00%-71.50%. 0.00%-68.95% and 1.12%-62.24%,respectively. [Conclusions] Reducing the use of specific pesticides in the particular growth period of rice could reduce ecological impact and dietary exposure significantly. Pymetrozine plays a key role for ecological impact, followed by difenoconazole, propiconazole and pretilachlor, which should be used appropriately. [ABSTRACT FROM AUTHOR]

Accurate and effective drought monitoring using remote sensing technology is essential for regional and global drought warning and forecasting. Especially, soil moisture (SM) is one of the key potential factors affecting agricultural drought. At present, most studies ignore the fact that soil moisture is a complex nonlinear coupling system，the research only using visible light, near infrared, short-wave infrared, thermal infrared and other remote sensing drought index has certain limitations in SM inversion. A new method of retrieving farmland SM of winter wheat at returning green stage based on MODIS and radial basis function neural network (RBFNN) is presented in this paper. Firstly, the adaptability of various MODIS-derived drought indices is analyzed in the period of seedling establishment of winter wheat, including soil water content, crop morphological change in water requirement, crop canopy water content and temperature and other parameters. Secondly, the correlation between the original remote sensing drought indices and the soil relative humidity 10 cm soil layer was analyzed. A comprehensive evaluation set of apparent thermal inertia (ATI), vegetation supply water index (VSWI), enhanced vegetation index (EVI), normalized difference infrared index band7 (NDIIB7), normalized multi-band drought index (NMDI) and temperature condition index (TCI) are selected to invert soil moisture of farmland. Finally, combining MODIS remote sensing drought index with RBFNN, the SM of farmland was retrieved synergistically, and the retrieved results were compared with those of BP-NN and linear regression (LR) models. The experimental study is conducted in Henan province of China, MODIS reflectance products (MOD09A1) and temperature products (MOD11A2) at returning green stage of winter wheat from 2001 to 2012 were used to extract remote sensing drought indices, and the global land cover product of MODIS (MCD12Q1) is selected to obtain cropland distributions. Soil moisture data is derived from the “China crop growth and development and farmland soil moisture ten-day dataset”, which contains the soil relative humidity of 10 and 20 cm soil layer observed every 10 days by 17 soil moisture stations. The results show that the average accuracy of SM inversion model using RBFNN and multiple drought indices is 93.27%, which is increased by 2.92 and 9.97 percentage points compared with BP-NN and LR model, respectively. Most of the data points of the three models are concentrated around the 1:1 line, which indicate that there is a good correlation between the predicted value and the measured value. Compared with BP-NN model and LR model, the deviation between predicted value of RBFNN model and the 1:1 line is the smallest, the higher the regression correlation coefficient is, the higher the determination coefficient is. SM is significantly correlated with ATI, NDIIB7 and VSWI in the early growth stage of winter wheat. Multi-band remote sensing drought monitoring indices can comprehensively reflect the changes of crop physiology and morphology under soil water stress, and also determine the retrieval accuracy of the humidity model simultaneously. In this paper, only winter wheat in returning green stage is selected as the research object, and the comprehensive evaluation index set selected is not suitable for SM inversion of other growth stages of winter wheat, the adaptability of different remote sensing drought indices in different growth stages needs further experimental study. The study provides a new case for regional SM inversion from remote sensing-based drought monitoring indices and neural network. [ABSTRACT FROM AUTHOR]

With the rapid development of industry and agriculture, lead from different sources is continuously released into the soil，and soil lead pollution has become one of the problems that need to be solved in soil pollution. Tracing of pollution sources and quantitative source analysis of pollutants are an important part of soil pollution prevention. In recent years，studies at home and abroad have shown that the lead isotope ratio method is one of the important methods for the analysis of quantitative sources of soil lead pollution，and has been widely used in the analysis of quantitative sources of soil lead pollution. This paper describes the principle of quantitative analysis of lead isotope and the current status and progress of the research on the application of this method at home and abroad, and a fingerprint library of lead isotope ratios in some provinces and cities in China was constructed through the method of literature research, in order to provide researchers with a certain reference when exploring the main lead pollution sources and their contribution rates in the area. Finally，some prospects are put forward for the limitation of the application of lead isotope ratio method in the analysis of quantitative sources of soil lead pollution. [ABSTRACT FROM AUTHOR]

Taking an industrial waste dump plate as the example，the pollution characteristics of heavy metals in the waste residue，soil and groundwater were discussed, and the carcinogenic risk and harm quotient of heavy metal pollution to human body were evaluated emphatically in this paper. Results show that： 1)8 kinds of heavy metals (As，Cu，Ni，Zn，Cd，Pb，Cr and Hg) in the slag exceed certain limits to some extent, with the maximum value of As (up to 91 % in the rate of exceeding standard) and a highly concentrated contaminated area for Cr. Contents of Cu，Ni，Zn and Cd in the soil are greater than local background values. As and Ni in the groundwater also exceed standards. 2)The carcinogenic risk levels of As，Ni and Cr in waste residues and soils all exceed the acceptable level of carcinogenic risk(l. 0 X 10-6)，with the highest carcinogenic risk of Cr，up to 5, 3 X 10-5. For the same heavy metal the carcinogenic risk values in waste residues are greater than in soils. 3)The hazard quotients of As，Cr and Cd in the waste residues are greater than the acceptable level(1), with the highest hazard quotients of Cr(up to 7, 5)， while the hazard quotients of all heavy metals (except As) in the soils are basically lower than the acceptable level. 4) The three exposure pathways are listed in descending order according to their contribution rates as follows: oral intake > inhaled soil particles > through skin contact. [ABSTRACT FROM AUTHOR]

[Objective] The aim of this paper is to explore the relationship between the main chemical components of flue-cured tobacco and soil chemical properties. [Method] All of 235 tobacco leaf samples and soil samples were collected from typical aromatic tobacco growing areas in Yunnan province. The main soil factors affecting the chemical quality of Yunnan fragrant tobacco leaves were studied by correlation analysis, stepwise regression analysis and principal component analysis. [Result] The contents of total sugar and reducing sugar in Yunnan tobacco were 30.87% and 27.21, respectively ;the contents of total nitrogen, nicotine and potassium were in the appropriate range, which were 1.91, 2.63% and 1.91% respectively ;The results showed that the pH value of the main tobacco planting soils in Yunnan was moderate, with an average of 6.3. The contents of total nitrogen, total phosphorus, available molybdenum and available sulfur were in the rich level. The contents of total potassium and humic acid were on the low level. The contents of organic matter, fulvic acid, available boron, water-soluble chloride ion, salt content and CEC (total amount of cation exchange) were in the middle level. The contents of total sugar, reducing sugar, starch and potassium in tobacco leaves were significantly positive correlation with total potassium in soil. Two sugar difference and sugar alkali ratio were significantly positive correlation with soil available molybdenum content. Two sugar difference was significantly positive correlation with soil humic acid content, and was significantly negative correlation with soil chloride ion content. [Conclusion] The contents of total potassium, available molybdenum, humic acid and water-soluble chloride ion in tobacco growing soil of Yunnan tobacco growing areas are the most important indicators affecting the chemical quality of tobacco leaves in Yunnan. [ABSTRACT FROM AUTHOR]

[ Objective) The objective of the paper is to provide the scientific basis for rational exploitation and protection of Bletilla striata Se enriched resources. [Method] The total Se content in soil for B. striata growth with different habitat and different cultivation years and Se content in B. striata harvested at different stages and different part of plants are determined, and the dynamie characteristics of Se in B. stri ata tuber with harvesting time was discussed, then the enrichment characteristics of B. striata tuher was analyzed to discuss the correlation of Se between growing soil and plant of B. striata. ( Result] The Se content in soil for wild B. striata growth was higher than that in soil for artificial cultivation of B. striata, and Se content in soil for wild B. striata was three times higher than that in soil for artificial cultivation. The Se content in soil cultivated B. striata with different planting years was three years two years > one year, while the Se content in B. striata tuber with different planting vears was one year the years > two years. The Se content in B. striata leaves was higher than that in Gibbs root and tuber. The Se content B. striata tuber did not vary significantly with harvesting time. The Se content in fibrous root and leaves of B. striata decreased first and then increased with harvesting time. Conclusion) The Se content in B. striata leaves is positively re lated to Se content in soil significantly, while Se content in B. striata fibrous root is negatively related to Se content in soil significantly [ABSTRACT FROM AUTHOR]

In order to expound the present situation and the potential risk of soil cadmium (Cd) in Guangxi, the paper collected and analyzed literatures about soil Cd in Guangxi which were published in recent 20 years. Based on the uniform criteria, 60 references were selected involving more than 30 areas in Guangxi, 7 090 samples. The paper summarized the distribution of soil Cd content distribution and the situation of soil Cd content exceeding the standard in Guangxi, so as to provide reference for relevant research, environmental policy making and environmental management. Results show that the soil Cd content in Guanxi ranges 0.040-244.1 mg·kg-1, with arithmetic mean and geometric mean 12.23 and 1.884 mg·kg-1, respectively. There were great differences in soil Cd concentration distribution between different functional areas. The average background soil Cd content in the research area is 0.153 mg·kg-1. The geometric mean of Cd content in agricultural soils and urban soils of non-mining areas were 0.467 and 0.320 mg·kg-1, respectively. The geometric mean of Cd content in the soil of mining area and in agricultural soil of mining area were 7.147 and 6.643 mg·kg-1, which were 46.71 and 43.42 times of the background soil Cd content. The majority of farmland soils are maintained at moderate pollution levels. Soils in several counties such as Nandan, Huanjiang, Jinchengjiang and Daxin were greatly affected by the pollution in mining area. There are areas not involved in the collected literatures. We recommend that control measures should be taken in Nandan, Jinchengjiang, Big Huanjiang, Yangshuo and Diaojiang areas, major investigations should be made in Baise Debao, Pingguo, Tiandong and Tianyang aluminum ore producing areas, and monitors on agricultural soil surrounding the mining area should be done. [ABSTRACT FROM AUTHOR]

【Objective】The objective of this paper was to understand the content and enrichment characteristics of trace elements in soil and plant(root) of wild Berberis in Guizhou Province and to provide the theoretical reference for cultivation of wild Berberis. 【Method】The contents of trace elements in soil and plant(root) were determined, and the correlation of trace elements between soil and plant(root) and the enrichment ability of plant(root) to trace elements were discussed. 【Result】Total amount of soil trace elements of Berberis guizhouensis Ying, B. pruinosa var. barresiana Ahrendt, B. weiningensis Ying, B. tsienii Ying and B. deinacantha Schneid. was Fe > Mn > Zn > Cu > Mo; B. veitchii Schneid., B. wilsonae var. guhtzunica(Ahrendt) Ahrendt, B.pingbaensis M.T.An was Fe>Mn>Cu>Zn>Mo. The highest content of the soil total amount of Cu was B. veitchii, the total amount of Fe was B. tsienii, the total amount of Mn was B. weiningensis, the total amount of Mo was B. deinacantha, the total amount of Zn was B. weiningensis. The highest content of the soil available amount of Cu was B. guizhouensis, the available amount of Fe was B. veitchii, the available amount of Mn and Mo was B. weiningensis, the available amount of Zn was B.wilsonae var.guhtzunica.The highest content of Cu and Mn in the roots of was B.wilsonae var.guhtzunica., Fe was B. deinacantha, Mo was B. deinacantha, Zn was B. tsienii. 【Conclusion】The trace elements between soil and plant(root) were correlated to some extent. The enrichment coefficient of Cu of B. guizhouensis was the highest and was greater than 1, and the other trace elements enrichment coefficient was less than 1.The content of the available trace elements in the soil of non-area of Berberis in Guizhou Province was more obvious than that of the whole area. [ABSTRACT FROM AUTHOR]

The change process of cultivated layer quality for slope farmland at plot scale is influenced by the interactive effects between erosive rainfall and artificial farming activities at different temporal and spatial scales. For a slope surface, there exists a successive erosion process of rainfall-runoff-infiltration and the consequence is first reflected in the quality of cultivated layer. Among the factors induced the erosion process at plot scale, terrain is an important factor because it could redistribute the ratio of rainfall--infiltration, which directly cause a different erosion process for an erosive rainfall and the different degradation degree during a rainy season and a growth season. Taking purple soil slope farmland as an example, the paper firstly analyzed the varying characteristics of cultivated layer quality of slope farmland, then quantitatively evaluated the effects of four terrain factors, altitude, slope angle, effective soil thickness and slope position on cultivated layer quality and their sensitivity of impact, adopted principal component analysis and evaluation model. The results indicated: 1) Such soil properties as cultivated layer thickness, soil organic matter and soil bulk density of cultivated layer were all within the suitable scope and soil nutrient properties were generally at middle & low levels. The variation coefficients of soil bulk density and soil total porosity showed weak variability (CV<10%), presenting 7.97% and 8.36% respectively and the other soil properties showed moderate variability. 2)Minimum data set for cultivated layer quality evaluation of purple soil slope farmland consisted of eight soil parameters, bulk density, penetration resistance, soil organic matter, clay content, cultivated layer thickness, soil shear strength, saturated water conductivity and bioavailable phosphorus. Soil physical properties are more important than chemical properties except soil organic matter for erosion control and crop growth of slope farmland. Evaluation based on the MDS revealed that the cultivated layer quality varied spatially over the slope, being 0.458 in the low part of the slope, 0.443 in the middle part of the slope and 0.417 in the upper part of the slope and the quality value of the lower slope was 3.39% and 9.83% higher than that of the middle slope and upper slope positions, respectively. 3) The factors affecting cultivated layer quality divided into four types: slope-angle impacted type, slope location impacted type, effective soil layer thickness impacted type and altitude impacted type and they accounted for 38.89%, 22.22%, 14.81% and 24.08% of the total samples taken from slope farmland respectively. The slope angle was the main determinant of cultivated layer quality because it could induce directly many ecological processes at plot scale. The slope angle and effective soil layer thickness could be modified by such soil and water conservation measures as terrace, biological ridge and soil improvement methods. But the slope location and altitude could not be modified easily only by selecting suitable crop system. 4) The quality of cultivated layer had positive correlation with its thickness and location in the slope, and negative correlation with altitude and slope angle. Sensitivity analysis revealed that the determinants were ranked in the order of altitude (-0.399) > location in the slope (0.192) > slope angle (-0.112) > effective soil layer thickness (0.110) based on their impact on cultivated lay quality. These results could provide some useful evaluation parameters and its regulating direction for cultivated layer quality, which contributed to the sustainable utilization of purple soil slope farmland. Furthermore, other samples of slope farmland should be studied in order to find out the critical values of MDS according to 2 functions of cultivated layer, erosion control and soil productivity. [ABSTRACT FROM AUTHOR]

In order to study the characteristics of microplastics and its response relationship with mulching years, irrigation methods in the farmland soil of Hetao Irrigation District, field sampling and indoor experiments were used in combination for in-depth study. This paper mainly analyzed the current situation of plastic film mulching in Hetao Irrigation District by considering the effects of mulching years (5, 10, 20 a) and irrigation methods (drip irrigation and surface irrigation under film mulching). The abundance, type, color, particle size and other distribution characteristics of microplastics in the farmland soil were analyzed and other microplastic surface features and attachments also were observed and discussed, which was supported by scanning the electric microscope and energy spectrometer. The results showed that the average abundance of microplastics in soil under the different mulching years (5, 10, 20 a) in Hetao Irrigation District was 2 526.00, 4 352.80, 6 070.00 pieces/kg. The maximum microplastic was 2133.50 pieces/kg in every layer of soil appeared at 0-10 cm soil layer by mulching 20 a, and the minimum microplastic was 678.00 pieces/kg at 20-30 cm soil layer by mulching 5 a. The average annual increasing rate of microplastics was 14.46% in the early stage (5-10 a), while the increasing rate in the later stage (10-20 a) was 3.95%. The abundance of soil microplastics was affected by different plastic-mulching years and irrigation methods. The abundance of microplastic in drip irrigation farmland was slightly larger than the surface irrigation farmland, and it decreased with the increase of soil depth. By further analysis, the major categories of microplastics were fibers (23.34%), fragments (26.31%), films (38.57%) and grains (11.78%); the colors of microplastics included black, transparent, green, red, blue, etc., with the proportions 24.56%, 23.83%, 19.34%, 16.52% and 15.75% respectively. In the 0-10 cm soil layer, the main color of microplastics was black and it accounted for 30.25% of the total microplastic; in the >10-20 and >20-30 cm soil layer, the main color of microplastics were transparent, accounted for 30.15% and 29.23% of the total microplastic. The particle size exhibited a downward trend with the increase of the mulching years, and the majority of particle size less than 1 mm. In addition, with the increase of mulching years, microplastics particle size in >0-10, >10-20, >20-30 cm soil layer was gradually decreased, and there was no significant relationship between size and irrigation method (P>0.05). The surface features of microplastic samples were rough and irregular pores existed on it, and fiber, thin film and fragments microplastics had regular micropores, while the grain microplastic surface pores were irregular and concave. The porous properties of microplastics in soil made the characteristic of greater specific surface area carried by it. This characteristic could increase the adsorption of other pollutants and microorganisms from the soil; and there were stable iron oxides and rare earth elements on the surface. The research is of great significance to clarify the distribution and harm of microplastics in the soil of the Hetao Irrigation District. [ABSTRACT FROM AUTHOR]

The investigation site is located in Jinggouxing watershed (from 26°10′31″N to 26°12′33″N and115°9′3″E to 115º11′39″E) in the north of Gan County, Jiangxi Province, China. The soil type is mainly red soil developed by granite. The collapsing gully area is 95.8 hm², which belongs to the intensity erosion area of the hills and mountains in the south of Jiangxi. Due to the sudden, violent, serious damage, and difficult to manage characteristics of collapsing gully, it has severely affected the local ecological environment and residents' lives, so it has become an important research direction for soil and water conservation. Collapsing gully is affected by hydraulic and gravity erosion. Among them, the hydraulic erosion of collapsing gully is mainly affected by surface runoff. The instability of the collapsing gully wall gradually increases through the undercutting effect of runoff, and then develops under the combined action of hydraulic and gravity erosion. Soil infiltration is the premise and basis of surface runoff. By analyzing the infiltration characteristics of collapsing gully soil, we can further understand the process of soil erosion by collapsing gully soil. In recent years, the disc infiltration meter has been widely used to determine soil hydraulic characteristics due to its fast and easy operation. In this paper, a disc infiltration instrument was carried out under four pressure heads (-9, -6, -3, and 0 cm) on the collapsing gully soil at three different developmental stages (initial stage, active stage and stable stage) and three parts (catchment, slope and channel). The basic physical and chemical properties of collapsed hills at different developmental stages were studied, and the correlation between the developmental stages and parts of collapsing gully to the basic physicochemical properties was analyzed. The variation of soil infiltration rate with different infiltration heads at different developmental stages and parts of the collapsing gully was plotted. According to the measured values of soil hydraulic conductivity and Gardner's constant α, the effects of collapsing gully at different developmental stages and their parts on the soil hydraulic conductivity and soil pore classification contribution to flow were analyzed. The results showed that soil infiltration properties were affected by soil sand content, pressure head, soil pore size distribution, soil erosion and space parts. The higher the sand content in the soil, the more severe the soil erosion would be, which would affect the soil infiltration characteristics. When the pressure head was 0, the stable infiltration rate at the collapsing gully in the developmental stable period was the highest, 1.01 and 1.40 times higher than that in the collapsing gully at the initial stage and active stage of the collapsing gully. With the decrease of the pressure head, the stable infiltration rate of the soil in the three different developmental stages gradually decreased. The soil hydraulic conductivity of different parts of the collapsing gully was basically similar under different pressure head conditions. There was no significant difference in soil hydraulic conductivity and Gardner's constant α at three different developmental stages. Except for the hydraulic conductivity at a pressure head of -9 cm, the soil hydraulic conductivity and the Gardner constant α values at different parts of the collapsing gully were significantly different. As the degree of erosion increased, the contribution rate of macropores to flow at different developmental stages increased. The parts of collapsing gully significantly affected the contribution rate of macropores, mesopores 2 and micropores to flow, it could be seen that the part of collapsing gully was an important factor which affected the hydraulic properties of soil. The results could provide some references for the soil erosion process of the collapsing gully soil at different developmental stages in the southern china [ABSTRACT FROM AUTHOR]

[Objective]This paper aimed to study the selenium contents in soil and tea leaves at different planting year tea trees( la, 5a, 10a, 15a). [ Method] Field sample investigation and indoor analysis method were measured. [ Result] (i) The crown, stem and branch of tea trees increased and tree density decreased with increasing planting age. (ii) Soil nutrients (Organic carbon, total nitrogen, total phosphorus, total potassium, available nitrogen, available phosphorus and available potassium) first increased and then decreased from 1 to 15 years of tea trees, which showed 10 a > 15 a >5 a > 1 a. (iii) Water extract, tea polyphenols, caffeine and free amino acids first increased and then decreased from 1 to 15 years of tea trees, which showed 10 a > 15 a >5 a > 1 a. (iv) Total selenium content, total selenium enrichment coefficient and effective total selenium enrichment coefficient in soil and tea first increased and then decreased from 1 to 15 years of tea trees, which showed 10 a > 15 a >5 a > 1 a. (v) Correlation analysis showed that the total selenium content in soil was significantly positively related with soil nutrient, and there was the correlation of the tea full selenium and effective selenium with soil physical and chemical properties but not significant (P > 0.05). [ Conclusion ] The main influencing factors for soil selenium were organic carbon (load coefficient was 0. 689) and total nitrogen (load coefficient was 0.702) , and the main influencing factors for the selenium of leaves were the water extract of tea ( load coefficient was 0. 623 ) and tea polyphenols (load coefficient was 0.726). [ABSTRACT FROM AUTHOR]

[Objective]The present paper aimed to clarify the relationship between soil nutrients and chemical components of tobacco leaves in Kunming tobacco area, so as to provide theoretical basis for the production of high-quality flue-cured tobacco in Kunming tobacco planting area.[Method]The relationship between soil nutrient status and chemical composition of flue-cured tobacco in Kunming tobacco area was studied by descriptive statistics and canonical correlation analysis.[Result] The results showed that the pH value of tobacco planting soil in Kunming tobacco area was generally suitable,content of available nitrogen was higher, and the content of effective phosphorns was was moderate but not balanced. The content of available potassium was abundant, and chloride content was at medium low level, but the distribi and reducing sugar of tobacco leaves in Kunming tobacco growing area was high, the alkali ratio were moderate, potassium and chlorine content were relatively low, but but potassium and chlorine were relatively High. Canonical correlation analysis showed that there was a significant correlation between soil nutrients and the main chemical components of tobacco leaves in Kunming tobacco growing areas. [Conclusion] Within a certain range, the decrease of soil pH value, oiganic matter and chloride ion content was consistent with the decrease of nicotine and total nitrogen in flue-cured tobacco leaves; the content of available potassium and available phosphorus in soil was consistent with the increase of total sugar, reducing sugar, potassium content, nitrogen-alkali mtio, potassium-chloride ratio and sugar-alkali ratio in flue-cured tobacco leaves. [ABSTRACT FROM AUTHOR]

Ningxia Helan County was taken as the research area in this paper to study the distribution characteristics and ecological risk of heavy metals in farmland soil in northwest China. 140 topsoil samples were collected aiming to analyze and measure the concentration of Cr, Ni, Cu, Zn, As, Cd and Pb belonging to heavy metal elements. The distributions, soil environment status and ecological risk of the seven heavy metals were studied by Nemerow pollution index and Håkanson potential ecological risk index methods. The results showed that concentrations of Cr, Ni, Cu, Zn, As and Pb were all lower than the second-level of Environmental Quality Standard for Soils of China except that concentrations of Cd of 1.42% samples were appeared to exceed the standard. Compared with the background values, seven heavy metals of all samples showed different degree accumulation, in which Cd, Ni elements beyond the background value ratio reached 100% and 85%. Spatial distribution of the concentrations of the seven heavy metals had obvious accordance. The content of each element was evenly distributed. The high content of each element was concentrated in the central and eastern part of Helan County, which was related to human activities. The calculation results of single-factor pollution index showed that among the 140 soil samples, 0.71% of Cd were moderate contamination, 7.14% of Ni and 5% of As were slight clean, Cr, Cu, Zn, Pb of all samples were all clean. According to the individual potential ecological risk index（Ei r）of heavy metals, the average potential ecological risk index of Cd element was 97.68, which indicated that Cd had reached the serious risk level, becoming the main element of potential ecological risk. All in all, the quality of farmland soil in Helan County of Ningxia is good, but it is noteworthy that the concentration of Cd, Ni has a serious accumulation. [ABSTRACT FROM AUTHOR]

[Objective] The purpose of this paper is to explore the relationship between the cultivation patterns and rhizosphere soil microbial populations. [Method] The rhizospheric soil physical and chemical properties of the apple orchard with different cultivation and management in the main apple producing areas of Zhaotong, Yunnan, were tested. High throughput sequencing technology was used to determine the 16SrDNA and ITS sequences of soil microbes, and the microbial diversity was analyzed. [Result] The study showed that the contents of organic matter, nitrate nitrogen, ammonium nitrogen, available phosphorus, available potassium, suerase, cellulase and urease in the rhizosphere soil of the boutique orchard and the ordinary orchard were higher that of the extensive orchard, while the contents of alkaline phosphatase and catalase were opposite. The genetic relationship of the bacterial genus populations in the common orchard the boutique orchard was relatively elose, but that of in the extensive orchard was far. The populations of the fungal genus detected in the rhizosphere soil of the three types of orchards were related to the type of orchard, and the genetic relationship of the fine orchard fungi was far. [Conclusion] The study proves that there are clearly beneficial, harmful, neutral and unknown microorganism populations in the rhizosphere soil of three types of orchard, and the different cultivated ways impact microorganism population then impact apple growing. [ABSTRACT FROM AUTHOR]

[Objective] This purpose of the article was to prove effects of land use types on soil quality, and to offer reference for ecological civilization construction and sustainable development of social economy in fragile karst environment of western Guizhou. [Method] Five different land use types (farmland, abandoned land, natural grassland, artificial grassland and forest land)were researched to explore their influences on soil quality by means of field experiments and laboratory analysis. [Result] The different land use types resulted in significant differences in soil bulk density and porosity. Hie forest land had the best soil bulk density and porosity, and the farmland had the worst. File value of soil field moisture capacity of five land use types ranged from 34.01 % to 48. 38 % which resulted in a significant difference. The pH values of five land use types ranged from 4. 59 to 5.53, and the farmland had the minimum of pH value. The soil cation exchange capacity of forest land, artificial grassland and abandoned land was higher than that of natural grassland and farmland. The descending order of five land use types according to the soil organic matter content (28.4-76. 27 g/kg) was forest land, natural grassland, artificial grassland, farmland and old field. The contents of total N, total P, available N and available P were the highest in farmland. The available indexes of total K and available K were less than 0.9 in difference land use types, and there was significant different among them. The soil available Cu and available Zn index of the five land use types ranged from 6. 50 to 14. 65. Based on the comprehensive indices of soil nutrients, five land use types were listed in descending order; forest land, natural grassland, artificial grassland, abandoned land and cropland. The comprehensive index of forest was about 1.68 times to that of farmland. [Conclusion] Soil quality of grassland and forest land was better than that of farmland and abandoned land. The conclusion of this paper was to provide the basis for rational development and utilization of land resources. [ABSTRACT FROM AUTHOR]

In order to solve the problems of high resistance and high power consumption of rotary tillage and land preparation, the rotary blade is studied based on theoretical analysis, simulation and field experiment in this paper. First, a wedge drag reduction rotary blade is designed based on the theoretical force model of cutting tools in mechanical soil dynamics. Second , the three-dimensional model of the national rotary blade and the wedge drag reduction rotary blade is established by using the Inventor software and the simulation experiment is carried on. The cutting soil model of 2 kinds of rotary blades is established by using HyperMesh software, and the material parameters, boundary constraints and working parameters are defined. On this basis, the soil cutting process, stress and cutting resistance are analyzed. It is proved that the wedge drag reduction rotary blade design is reasonable. In order to verify whether the wedge drag reduction rotary blade meets the strength requirement, the stress of the rotary blades is analyzed, and the cutting resistance of the national rotary blade and the wedge drag reduction rotary blade are compared. Third, field comparative experiments are carried out on national rotary blade and wedge drag reducing rotating blade with the evaluation indexes of torque, power consumption and soil breakage. The results show that the cutting resistance of the wedge drag reduction rotary blade is smaller than that of the national rotary blade; the maximum stress of the national rotary blade is 35.68 MPa and the maximum stress of the wedge drag reduction rotary blade is 29.49 MPa, which is less than that of the national rotary blade and far less than the yield strength of the material 430 MPa. On the premise of ensuring the strength of the blade body, the weight of the wedge drag reduction rotary blade is reduced by about 50 g, which is about 8.3% lower than that of the national rotary blade. The maximum cutting resistance of the national rotary blade is 530 N, the average cutting resistance is 375.5 N, and the maximum cutting resistance of the wedge drag reduction rotary blade is 510 N, the average cutting resistance is 335.5 N, the average cutting resistance of the wedge drag reduction rotary blade is 10.65% lower than that of the national rotary blade, which proves the feasibility of the wedge drag reduction rotary blade designed; The average torque of the wedge drag reduction rotary blade is 11.35% lower than that of the national rotary blade. In the working process of rotary blades, the average power consumption of the national rotary blade is 74.2 kW, the average power consumption of the wedge drag reduction rotary blade is 67.3 kW, and the average power consumption of the wedge drag reduction rotary blade is 9.29% lower than that of the national rotary blade. The average breaking rate of soil of the national rotary blade is 75%, and the average breaking rate of wedge drag reduction rotary blade is 79%, which is 4% higher than that of the national rotary blade; After continuous 33 hm2 tillage, rotary blades did not break, and the average wear of the national rotary blade is 98.5 g, the average wear of the wedge shaped drag reduction rotary blade is 97.3 g, the wear difference is 1.3%, and the wear degree is the same. The wedge drag reduction rotary blade can effectively solve the problems of high resistance and high power consumption of rotary blade, which is helpful to accelerate the development of arable land machinery, improve the mechanization level of cultivated land, and reduce the production cost of crops. [ABSTRACT FROM AUTHOR]

[Objective]This study aimed to investigate the concentrations of soil mineral elements among different interplanting patterns, and provide scientific basis for the rational fertilization of Zanthoxylwn bungeanum and its intercropping plants in desertification area of middle Guizhou province. [Method] In this paper, the soils of 8 + 1 (Zea mays, Ipomoea batatas, Hylocereus undulates, Amomum villosum, Brous-sonetia papyifera, Lonicera japonica, Euchresta japonica, Arachis hypogaea and the control group of Z. bungeanum) kinds of intercropping patterns were used to study the concentrations of soil mineral elements among different interplanting patterns. [Result]There were differences in the concentrations of soil mineral elements among different interplanting patterns. Compared with the forest of Z. bungeanum, except for the slightly increased Ca content in Z. nrnys pattern soil, the contents of Ca, Mg and S in the other intercropping patterns decreased to different extents. The content of Cl, Si and Co in the intercropping pattern decreased except for the Co content in the L. japonica pattern. Moreover, the Ni and A1 contents were higher while the Z. mays and II. undulates pattern were lower. Except for the Z. mays and A. hypogaea pattern, the content of Na and Se in the different intercropping patterns decreased to different extents. Only the content of As, Pb, Cr, Cd, Ti and Sr in the H. undulates pattern was reduced, and others were increased. [Conclusion] Interplanting patterns of Z. bungeanum were beneficial to improve the concentrations of soil mineral elements. Interplanting patterns of Z. bungeanum with I. batatas, A. villosum, Z. mays, B. papyifera and L. japoni-ca should pay attention to the addition of Mg, S, Na elements, while those of I. batatas, A. villosum should add Ca, Se ele- ments. [ABSTRACT FROM AUTHOR]

[Objective]The aim of this paper was to study the influence of rubber tree growth of different varieties on soil nitrogen in rubber tree plantation of different ecological regions in Xishuangbanna and understand the relationship between soil nitrogen and rubber growth. [Method] Soil and the leaves of different rubber tree varieties in rubber tree plantation with different rubber tapping years from different ecological areas (Jinghong, Mengla and Menghai) of Xishuangbanna were collected to analyze spatial variation characteristics and the relationship of soil nitrogen and rubber leaf nitrogen. [Result] Soil nitrogen of different varieties in rubber tree plantation had a big difference in three ecological regions of Xishuangbanna. Among the three sampling ecological regions, soil nitrogen content in Jinghong site was the highest. The contents of NH4-N and NO3-N were low, and NO3-N variation was high. Soil total nitrogen in GT1 rubber tree plantation was higher than that in RRIM600 and yunyan-774 rubber tree plantation. Soil total nitrogen content increased with the increase of rubber tapping a-ges. The contents of alkali-hydrolyzale nitrogen, NH4-N and NO3-N changed with rubber tapping ages, and the contents of soil NH4-N and NO3 -N in young rubber tapping ages were lower than that in old rubber tapping ages. Total nitrogen content of rubber tree leaves in Jinghong site was the highest than that in Mengla and Menghai, and the content of total nitrogen in young rubber tapping ages was higher than that in old rubber tapping ages. Total nitrogen, alkali-hydrolyzale nitrogen and NH4-N in protection areas soil had significant positive correlation with the total nitrogen of rubber tree leaves, but NO3-N had extremely significant positive correlation with the total nitrogen of rubber tree leaves. Among different forms nitrogen in planting areas, only soil NH4-N and NO3-N had significant positive correlation with the total nitrogen of rubber tree leaves. [Conclusion] Nitrogen contents of soil and rubber tree varied with rubber tree varieties, rubber tapping ages and growth environment, and different rubber tree varieties and rubber tapping ages could have the significant impact on soil nitrogen content in rubber plantation. [ABSTRACT FROM AUTHOR]

Determination of soil organic matter by oxidation of potassium dichromate (HJ615-2011) u-ses oil bath heating to digest organic matter. Since the oil bath heating is prone to oil spillage and the oil stain attached to the wall of pipe is difficult to clean，this paper focuses on the possibility of using dryer heating instead of the oil bath heating at the common temperature of dryer. The results of the study show that，at the temperature of 135 C(the temperature is in the dryer common temperature (RSD) of potassium dichromate oxidation method is 0. 294% - 1. 593% , the recovery rate is 99% - 1 03% by dryer heating, compared with the result that the RSD is 0. 386 % - 1. 945 % and the recovery is 96 % - 105% by oil bath heating. Therefore, the precision and accuracy of the oxidation of potassium dichromate is improved by using dryer heating, and the dryerheating method is more appropriate to determine organic carbon than traditional oil bath heating method. [ABSTRACT FROM AUTHOR]

【Objective】 The aim of this paper is to provide a reference for scientific, reasonable and efficient utilization of land resources in dry-hot valley stony desertification area of Guizhou. 【Method】 The SOC, TN, TP and TK content of soil samples with 0-20 cm depth from six typical soil plots of Hylocereus undulatus, Lonicera japonica, Juglans regia, Tectona grandis, Zea mays and Zanthoxylum bugeanum in dryhot valley stony desertification area of Guizhou was determined and then the ecological stoichiometric characteristics of C, N, P and K in soils was statistically analyzed by using the ecological stoichiometric method. 【Result】 The average content of SOC, TN, TP and TK in soil samples with 0-20 cm depth from six typical soil plots is 19.16-70.17, 1.69-6.79, 0.06-3.12 and 8.60-77.04 g/kg respectively. The ratio of C:N, C:P, N:P, C:K, N:K and P:K is 6.318-21.028, 11.400-552.310, 1.804-46.354, 0.461-5.651, 0.073-0.502 and 0.003-0.040 separately. The SOC content of soil is significantly and positively correlated with C:K and P:K. The TN content of soil is significantly and positively correlated with P:K, and significantly and negatively correlated with C:N and C:P. The TP content of soil is significantly and positively correlated with P:K, and very significantly and negatively correlated with C:P and N:P. The TK content of soil is very significantly and positively correlated with P:K, very significantly and negatively correlated with C:P and N:P, and significantly and negatively correlated with C :K. The SOC has the promotion effect on C:K and N:K. The TN, TP and TK content of soil has the promotion effect on P:K in soil also. The TN, TP and TK content in soil has the inhibition effect on C:N and C:P, C:P and N:P, and C:P, N:P and C:K respectively. In addition to the S function between C:K and N:P, there is a unitary quadratic function relationship between different ecological stoichiometric ratios. 【Conclusion】 The soil fertility can be improved by applying exogenous P fertilizer in agricultural production because the quicker decomposition of organic matter in soil speeds up consumption of soil nutrients and results in TP deficiency of soil in dry-hot valley stony desertification area. The combined application pattern of organic manure and inorganic fertilizer should be used in management of soil nutrients in dry-hot valley stony desertification area. [ABSTRACT FROM AUTHOR]

【Objective】 The present paper aimed to provide the theoretical basis for optimization management of mulberry field by verifying nutrients and ecological stoichiometry characteristics of soil from returning farmland to mulberry field in stony desertification region. 【Method】 The nutrients and ecological stoichiometry characteristics of soils with different soil depth of Libo mulberry field(returning farmland to forestry for one year) and Bijie mulberry field(returning farmland to forestry for ten years) in different season were studied by the space replacing time method and actual investigation. 【Result】(i) The returning farmland to mulberry field is beneficial for improvement of soil nutrients in stony desertification region. The nutrients of mulberry present the fluctuating variation trend during the year-round growth process. The C, N and P in mulberry field soils with different soil depth has a‘ surface segregation’characteristics and their content gradually reduces with increase of soil depth. The organic carbon and total Ca content in the soil of Bijie mulberry field(returning farmland to forestry for ten years)shows a decline-rise-decline trend, the total nitrogen and total phosphorus content decreases continuously and total potassium content presents a first decline and then rise trend.(ii) C/N, C/P and N/P ratio of the soil from Bijie mulberry field(returning farmland to forestry for ten years) increases but its C/K, C/Ca and N/K ratio decreases. The C/P and N/P ratio presents a rising trend with seasonal variation but a rapid decrease trend with increase of soil depth. 【Conclusion】 The phosphorus is the main limitation factor to influence soil of mulberry fields, followed by nitrogen factor. The needed nutrients for mulberry should be supplied and the variation between different soil elements should be paid attention in management of mulberry fields. The soil ecological stoichiometry ratio of the mulberry field from returning farmland to forestry is significantly related to its nutrients. The contribution of organic carbon and total nitrogen is positive to soil C/P, C/K, N/P and N/K. The contribution of total Ca is positive to soil C/K and N/K. The contribution of total phosphorus is negative to soil C/P and N/P. The contribution of total potassium is negative to soil total Ca and C/Ca. [ABSTRACT FROM AUTHOR]

As the largest distribution area of black soil in China, Heilongjiang Province is undertaking important responsibility of food safety for country. However, due to lack of protection, it has become one of those regions undergoing the most serious soil erosion and is gradually losing its basic role of important agricultural production. Soil erodibility index (K-value) is not only an important parameter for evaluating soil's sensitivity to erosion and forcasting soil erosion process but also a key foundation for monitoring and planning of soil and water conservation. In this paper, in terms of soil census data, the characteristics of K-value were analyzed by traditional statistical and geostatistical methods. Results showed that: 1) The soil texture presented significant difference among main soil types; the contents of coarse silt, fine powder and clay obeyed normal distribution, and their spatial correlations were weak. 2) The average K-value of aeolian sandy soils was the largest (0.0281), that of albic soils was the smallest(0.0234), and all K-value of main soil types had weak variability. 3)The average K-value of sandy loam was the largest (0.0281) while moderate clay had the smallest K-value(0.0201). Generally, the average K-value reduced with the increasing physical clay content as well as the decreasing physical sand content, and all soil textures had weak variability but for heavy clay having moderate variability The difference of soil texture either in same soil type or among different soil types was effected by their components content, and this difference was also reflected in K-value. 4) There was a significant linear relationship (R²=0.83) between the average K-value and soil surface thickness and furthermore, the K-value would gently descend when the thickness increased. In other words, the thinner top soil resulted from soil and water loss can cause the increasing K-value and amplify the probability of soil erosion. Thus, the top soil would become thinner and thinner and even disappear. 5) The K-value's distribution characteristics of the areas with various soil erosion types showed obvious difference, however, those regions belonging to same soil erosion type had similar distributions although they were in different soil erosion intensity levels. In water erosion region, the distribution area of different K-values showed an increasing trend in the section from 0.0220 to 0.0241, and got the largest area in the interval from 0.0241 to 0.0245 while a decreasing trend occurred in the zone from 0.0245 to 0.0276. Generally, the distribution area of K-value increased with the increasing of K-value in wind erosion region. The K-value of freezing-thawing erosion region converged in the zone from 0.0258 to 0.0268, and the K-value of engineering erosion region was centered in the zone from 0.0229 to 0.0245. 6) The K-value had a moderate spatial correlation, and showed a gentle linear downward trend from the west to the east, as a distribution of concave parabolic shape occurred in north-south direction. In addition, the maximum K-value mostly appeared in the area of aeolian sandy soil, and the two minimum K-value areas were almost related to the areas of black soils and albic soils, respectively. We also found the distribution features of K-value coincided with the soil and water conservation regionalization well. The K-value grid database produced in this paper would provide basic parameters for soil erosion monitoring and prediction, and controlling of soil and water loss, especially provide scientific basis for the protection and restoration of black soil resources, and impose a positive effect on sustainable grain production safety in the black land. It was necessary to note that the data used in this work were a little old and their soil profile samples were not collected randomly, and thus this shortage of the data may make our results less reliable. Besides, since we lacked newer data, we didn't further analyze relevant spatial and temporal dynamic changes of K-value. [ABSTRACT FROM AUTHOR]

China is the country with the highest reserves of antimony in the world, a large amount of antimony resources are lost to the environment due to unreasonable use. As an oncogenic element, the exceeded antimony content seriously threaten to human health. However, due to people's less concern about antimony pollution as well as the immaturity of relevant governance techniques(especially phytoremediation), the situation of antimony pollution in China is not optimistic. This paper reviewed the distribution, pollution status, characteristics and accumulator plants of antimony in China, and according to the research advances on screening of antimony accumulator plants in field, evaluated their application prospect for reducing the environmental risks of antimony contamination using phytoremediation. [ABSTRACT FROM AUTHOR]

In order to understand copper concentration and distribution in soil of Xijiang River Basin of Guangxi and evaluate the ecological risk, this paper collected 1 381 dryland soil samples, 729 paddy soil samples, 129 mining soil samples and 293 background soil samples during 2012-2015, and measured the content of copper in soils. According to statistical analysis, the influence of copper accumulation in different types of soil was explored, the spatial distribution of copper content was interpolated through geostatistical analysis and the risk was assessed. The results showed that the geometric mean of copper concentrations was 27.60 mg/ kg. The copper concentrations in dryland, paddy, mining and background soil ranged from 0.3 to 317.91, 3 to 495.81, 7.5 to 2 287.66 and 0.68 to 284.27 mg/kg, and the geometric means were 27.75, 25.19, 79.38 and 21.21 mg/kg, respectively. The copper concentration in mining soil was significantly higher than in other soils. Compared to baseline value, the corresponding exceeding rate of mining, dryland and paddy soil were 33.25%, 3.76% and 0.68%, respectively. The spatial pattern of copper content in Xijiang River Basin showed medium autocorrelation with strong structural variability. Clean soil occupied 61% in Xijiang River Basin, while 36% of soil belongs to light pollution soil which mainly distributed in Nandan, Du’an, Wuxuan and Guiping counties where lead-zinc ores are concentrated. Generally speaking, copper content in soil of Xijiang River Basin had some accumulation but the pollution was not serious and it was assessed to be safe. Besides, the risk should be prevented in the areas of Nandan, Du’an, Wuxuan and Guiping counties. [ABSTRACT FROM AUTHOR]

At present, sulfur in soil is mainly determined by X-ray Fluorescence Spectrometry and tube furnace combustion iodine methods. The analysis speed of these two methods is slow, and the analysis accuracy is poor for both high and low content samples, difficult to meet the requirements of accurate and rapid determination of many samples. In order to improve the speed and accuracy of analysis, a new method for the determination of sulfur in soil samples by Inductively Coupled Plasma-Optical Emission Spectrometry combined with four acids digestion was developed. In this paper the digestion effect of aqua regia, aqua hot water bath and HC1-HN03-HF-HC104 is compared. The four acids digestion method was proven to better dissolve sulfur in soil samples. The method is simple, raj)id and accurate with a low detection limit of 10 μ/g, analysis range between 33.3 μ/g and 50000 μ/g, and relative standard deviation between 0.47% and 4.05%. Many elements such as potassium, sodium, calcium, magnesium, iron, manganese, beiyllium, lithium, lanthanum, cerium, scandium, vanadium, cobalt, nickel, and titanium can be determined simultaneously in a solution without increasing analysis cost. The method, which has been verified with actual samples, is suitable for application in the geological industry. [ABSTRACT FROM AUTHOR]

Combined with the current research progress and shortcomings on spatial distribution characteristics and scale effects of soil properties, using a combination of variogram theory, spatial autocorrelation theory, multi-fractal theory and other methods from the aspects of the spatial variability of soil properties and the structure, the paper gradually revealed the spatial distribution characteristics of SOC (soil organic carbon) and its scale effects under 4 kinds of scales. The results showed that: Ratio of nugget to sill of SOC under 15, 25, 35 and 45 km scales were 61.78%, 42.65%, 49.98% and 39.34%, respectively, which showed a moderate spatial correlation. The spatial correlation from high to low was 45, 25, 35 and 15 km in turn. Except the 15 km scale, the spatial variability caused by random factors including representative measurement error and the micro-scale process, was less than the structure variance, namely the ratio of nugget to sill was less than 50%, the structural factors were dominant, and spatial variability from the random part showed a decreasing trend with the scale increasing. The variation function couldn't be described with discrete characteristics (i.e. spatial negative correlation), which was also impossible to make a significant test for variable range. As the separation distance increased, the Moran index decreased from full positive to negative, then the positive and negative values alternately occurred, and eventually the values turned out to be negative totally. Nearer positive correlation distance represents the spatial correlation distance, which is the first cross point of positive and negative conversion under different scales, and were 1 607, 7 520, 8 649 and 9 053 m for 15, 25, 35, and 45 km scale. With the scale increasing, the spatial correlation distance increased, and compared to the change range in the semi-variation function, it became smaller with varying degree under different scales except 15 km scale. The greater the scale, the greater the total spatial autocorrelation. The order for standardized statistic under different scales was 15 km < 45 km <35 km < 25 km, which increased firstly and then decreased with the scale. All random scale accounted for less than 5%, and on the whole each scale had good spatial structure. The multidimensional fractal parameter value under 25 km scale was the largest, indicating that the SOC content in this scale was mainly concentrated in a dense area. The magnitude of variation of Rayleigh dimension of SOC under 4 kinds of scales was consistent with that of width of multidimensional spectrum. The spatial distribution of SOC is a typical fractal dimension. Multifractal method is a tool for describing the spatial heterogeneity of SOC. It can reveal the scale variation characteristics of spatial heterogeneity of SOC. No matter what kind of scale, specific value of the measured value based on the Mkrige method agreed well with the predicted value, and the coverage ratio of specific value was above 85%. Spatial distribution characteristics of SOC were deeply revealed through combining variation function, spatial autocorrelation, multi-fractal and Mkrige method from spatial variability, spatial correlation and spatial structure in research area. The results can provide a method to the research on the spatial distribution characteristics of SOC in relatively flat agricultural region. However, due to the different combinations of artificial and natural factors, the spatial variability, correlation and structure will vary with scale change. [ABSTRACT FROM AUTHOR]

This paper reviewed the definition, research approaches and methods of plant-soil feedback and its research progress and problems. Plant-soil feedbacks involve two-step processes; plant changes the abiotic and biotic conditions of its associated soil; these changes in soil conditions may increase or decrease the growth of eonspeeifies, resulting in positive or negative plant-soil feedbacks, respectively. Plant-soil feedbacks can affect plant perlormanee and plant-competitive interactions, ultimately affecting community composition and diversity. Role of feedback in the succession process in the plant is uncertain. Growth enhancement of exotic and less negative feedback may result in that local species are competitively excluded, future climate change may cause changes in species composition and biodiversity loss, but resource complementarity and not too strong plant-soil feedbacks elfeets may lead to high productivity and diversity of mixed plant community. The key issues and further tasks of plant-soil feedback study were suggested as follows: (1) Design the experiment of plant-soil feedback in different ecosystems; (2) There were strong need to study reciprocating elfeets of plant and soil; using the molecular or genetic mean in plant-soil feedback; (3) Study on the mechanism of plant-soil feedback as a ecological factor. [ABSTRACT FROM AUTHOR]

[Objective]The aim of this paper is to provide the basic information and decision basis for rare plant conservation and tourism sustainable development in Fanjing Mountain Nature Reserve. [Method]The heavy metals in woodland soil with different profile, elevation and vegetation type in Fanjing Mountain Nature Reserve are investigated and evaluated and the enrichment characteristics is discussed by enrichment factor method. [Result] Cd and Pb content in soil decreases with increase of soil depth but Cu content in soil increases with increase of soil depth. Cr content in soil presents a decrease-increase-decrease trend with increase of elevation. Cd content in soil presents a first increase and then decrease trend with increase of elevation. Pb, Cu, H and As content in soil presents an increase-decrease-increase trend with increase of elevation. The content of heavy metals in soil with Taxus chine ns is , Euonynus hamiltonianus, Rhododendron and Davidia in-volucrata vegetation is Cr > Pb > Cu > As > Cd > Hg. The content of heavy metals in soil with Abies fanjingshanensis vegetation is Pb > Cr > Cu > As > Cd > Hg. The enrichment factor of Cu, Cd, Hg and Pb in soil with 0 - 20 , 20 - 40 and 40 - 60 cm depth is > 1. The enrichment factor of Cd, Pb and Hg in soil with an elevation of 500 - 1000. 1001 - 1500, 1501-2000 and >2000 m is > 1. The enrichment factor of Cu and As with an elevation of > 2000m is > 1. The enrichment factor of Cr with an elevation of 500 - 1000 m is > 1. The enrichment factor of Cr, Cd, Pb and Hg in soil with T. chinensis, E. hamiltonianus and I), involucrata vegetation is > 1. The enrichment factor of Cr,Cu, Cd, Hg and As in soil with Rhododendron vegetation is > 1. The enrichment factor of Cu, Cd, Hg and As in soil with A. fanjingshanensis vegetation is > 1. The soil of woodland in Fanjing Mountain Nature Reserve is mainly affected by Cd, Pb and Hg. [ABSTRACT FROM AUTHOR]

In this paper, the experiment area is dry and prone to soil erosion, in order to stop slope runoff and promote rapid vegetation restoration, a restoration program was implemented. So it is significant for grassland ecological construction to study on the effects of ecological restoration measures on soil properties and soil quality. A study had been done to investigate the different of 0-40 cm soil depth of soil properties and assessment of soil quality under different restoration measures in typical steppe grassland in Ningxia. We selected the sites that has been subject to enclosure(FY), contour trench(SP), fish-scale pits(YL), which were implement in 2001 and grazed(FM) (as a reference, traditional grazing with some supplement) grassland. The results showed that: 1) Soil bulk density of grazing grassland was the highest (P <0.05) whereas the soil clay content, field water holding capacity and total porosity were the lowest (P<0.05), and there was no significant difference (P > 0.05) in soil physical properties between enclosure, contour trench, and fish-scale pits grassland. 2) Soil organic matter and total nitrogen were the highest (P < 0.05) in enclosure grassland, followed by grazed grassland, and the lowest in contour trench. The content of total phosphorus was higher (P = 0.05) in grazed and enclosure grassland, but was the lowest (P < 0.05) in contour trench grassland. The available K content was the highest in grazed grassland the lowest in fish-scale pits grassland (P<0.05). The content of available N was highest in enclosure grassland but lowest in contour trench grassland which were 161.75 mg/kg and 77.17 mg/kg respectively (P<0.05). 3) Soil sucrase and urease activity showed FY>SP>YL>FM; protease and phosphatase activity both showed the highest (P <0.05) in enclosure grassland and the lowest (P <0.05) in the fish-scale pits grassland; the bacteria, actinomycetes and fungi were varied in each treatment; the amount of microorganisms showed FY>FM≈SP>YL whereas microbial biomass carbon and nitrogen showed FY>YL≈SP>FM (P<0.05). 4). As a whole, soil bulk density was negatively correlated with other indexes, and negatively correlated with clay content, field water holding capacity, total porosity, sucrase activity, urease activity, microbial biomass carbon and microbial biomass nitrogen (P<0.01). There was a significant positive correlation between soil organic matter, total nitrogen and available nitrogen (P<0.01) and the correlation between soil enzyme activity and soil microbial population (P<0.05). Soil capillary porosity (except soil microbial biomass nitrogen) and available potassium were not correlated with other indexes (P>0.05). 5) The comprehensive score of soil quality evaluated by the membership function factor analysis method was: enclosure> grazed> contour trench>fish-scale pits grassland. In summary, the enclosure grassland was more conducive to the restoration of typical grassland. Based on the study of the effects of enclosure, contour trench and fish-scale pits on the soil physical and chemical properties and biological traits, the membership quality of soil under different restoration measures was evaluated by membership function and factor analysis and can provide the basis for the ecological construction of typical grassland in Ningxia. The results showed that the enclosure was the most beneficial to the restoration of soil quality in degraded grassland in the study area. [ABSTRACT FROM AUTHOR]