Variation Characteristics of Root Traits of Different Alfalfa Cultivars under Saline-Alkaline Stress and their Relationship with Soil Environmental Factors

Soil salinization is the main factor that threatens the growth and development of plants and limits the increase of yield.It is of great significance to study the key soil environmental factors affecting plant root traits to reveal the adaptation strategies of plants to saline-alkaline-stressed soil environments.In this study,the root biomass,root morphological parameters and root mineral nutrient content of two alfalfa cultivars with different sensitivities to alkaline stress were analyzed with black soil as the control group and the mixed saline-alkaline soil with a ratio of 7:3 between black soil and saline-alkaline soil as the saline-alkaline treatment group.At the same time,the correlation analysis of soil salinity indexes,soil nutrient indexes and the activities of key enzymes involved in soil carbon,nitrogen and phosphorus cycles was carried out.The results showed that compared with the control group,the pH,EC,and urease(URE)of the soil surrounding the roots of two alfalfa cultivars were significantly increased,while soil total nitrogen(TN),total phosphorus(TP),organic carbon(SOC),andα-glucosidase activity(AGC)were significantly decreased under saline-alkaline stress.There was no significant difference in root biomass and root morphological parameters of saline-alkaline tolerant cultivar GN under saline-alkaline stress.The number of root tips(RT),root surface area(RS)and root volume(RV)of AG were reduced by 61.16%,44.54%,and 45.31%,respectively,compared with control group.The ratios of K^(+)/Na^(+),Ca^(2+)/Na^(+)and Mg^(2+)/Na^(+)of GN were significantly higher than those of AG(p<0.05).The root fresh weight(RFW)and dry weight(RDW),root length(RL),RV and RT of alfalfa were positively regulated by soil SOC and TN,but negatively regulated by soil pH,EC,and URE(p<0.01).Root Ca^(2+)/Na+ratio was significantly positively correlated with soil TN,TP and SOC(p<0.01).The absorption of Mg and Ca ions in roots is significantly negatively regulated by soilβ-glucosidase activity(BGC)and acid phosphatase activity(APC)(p<0.05).This study improved knowledge of the relationship between root traits and soil environmental factors and offered a theoretical framework for elucidating how plant roots adapt to saline-alkaline stressed soil environments.

A Comparative Study of Different Methods on Quality Assessment of Soil Environment Polluted by Zinc in Agricultural Production Areas——A Case Study in Shulan City of Jilin Province

[Objective] The aim was to explore evaluated precision on quality of soil environment polluted with zinc in agricultural production areas and to provide references for verification of production area.[Method] In Shulan City in Jilin Province,soils were sampled and analyzed in a laboratory using single-factor pollution index and GIS based spatial interpolation.The quality of environment polluted with zinc was assessed and related methods were compared according to Environment Quality Standard of Green Food Production Area.[Result] Spatial interpolation of zinc in soils based on GIS proved more precise than traditional methods;cokriging method with co-factors was higher in precision than common cokriging;cokriging method with zinc and organic matter was higher in precision than cokriging with zinc alone.[Conclusion] Quality assessment on environment polluted with zinc based on GIS interpolation is more scientific and reasonable than traditional methods.

Impact of Urbanization on Shanghai's Soil Environmental Quality

Heavy metal contents in the soils in the Baoshan District of Shanghai were monitored to evaluate the risk of soil environmental quality degradation due to rapid urbanization and to reveal the ways of heavy metal accumulation in soil during rapid urban sprawl. It was found that the soils in this district were commonly contaminated by Pb, Zn and Cd. Evaluated with a geo-accumulation index (Igeo), the rate of Pb contamination in soils was 100% with 59% of these graded as moderate-severe or severe; Zn contamination reached 59% with 6% graded as moderate-severe or severe; and Cd contamination was over 50%, with one site graded as moderate-severe and another severe-extremely severe. Metal contamination of soils around the Shanghai metropolis was mainly attributed to traffic, industrial production, wastewater irrigation and improper disposal of solid wastes. Because of continuing urbanization, the cultivated land around the metropolis should be comprehensively planned and carefully managed. Also the soil environmental quality of vegetable production bases in this area should be monitored regularly, with vegetables to be grown selected according to the degrees and types of soil contamination.

Effect of Reclamation on Soil Environment in Sanjiang Plain

Soil environment in Sanjiang Plain has changed greatly because of the reclamation on a large scale.The physical and chemical properties of soil have changed, and soil erosion, soil saline-alkalization and soil pollution occurred in some areas. These problems have obstructed the sustainable development of agriculture. For the sustainable use of soils in Sanjiang Plain, in this paper we raise some suggestions and countermeasures which might be references for experts and departments concerned.

Effect of deteriorated microstructures on stress corrosion cracking of X70 pipeline steel in acidic soil environment

In order to investigate stress corrosion cracking （SCC） of X70 pipeline steel and its weld joint area in acidic soil environ- ment in China, two simulating methods were used： one was to obtain bad microstructures in heat affected zone by annealing at 1300 ℃ for 10 min and then, quenching in water; the other was to get different simulating solutions of acidic soil in Yingtan in south- east China. The SCC susceptibilities of X70 pipeline steel before and after quenching in the simulating solutions were analyzed using slow stain rate test （SSRT） and potentiodynamic polarization technique to investigate the SCC electrochemical mechanism of different microstructures further. The results show that SCC appears in the original microstructure and the quenched microstructure as the polarization potential decreases. Hydrogen revolution accelerates SCC of the two tested materials within the range of-850 mV to -1200 mV vs. SCE. Microstructural hardening and grain coarsening also increase SCC. The SCC mechanisms are different, anodic dissolution is the key of causing SCC as the polarization potential is higher than the null current potential, and hydrogen embrittlement will play a more important role to SCC as the polarization potential lower than the null current potential.

Warming effects on plant biomass allocation and correlations with the soil environment in an alpine meadow,China

Alpine meadow ecosystem is fragile and highly sensitive to climate change.An understanding of the allocation of above-and below-ground plant biomass and correlations with environmental factors in alpine meadow ecosystem can result in better protection and effective utilization of alpine meadow vegetation.We chose an alpine meadow in the Qinghai-Tibetan Plateau of China as the study area and designed experimental warming plots using a randomized block experimental design.We used single-tube infrared radiators as warming devices,established the warming treatments,and measured plant above- （AGB） and below-ground biomass （BGB） during the growing seasons （May to September） in 2012 and 2013.We determined the allocation of biomass and the relationship between biomass and soil environment under the warming treatment.Biomass indices including above-ground biomass,below-ground biomass and the ratio of root to shoot （R/S） ,and soil factors including soil moisture and soil temperature at different depths were measured.The results showed that （1） BGB of the alpine meadow had the most significant allometric correlation with its AGB （y=298.7x~ （0.44） ,P〈0.001） ,but the relationship decreased under warming treatment and the determination coefficient of the functional equation was 0.102 which was less than that of 0.188 of the unwarming treatment （control） ; （2） BGB increased,especially in the deeper soil layers under warming treatment （P〉0.05） .At 0–10 cm soil depth,the percentages of BGB under warming treatment were smaller than those of the control treatment with the decreases being 8.52% and 8.23% in 2012 and 2013,respectively.However,the BGB increased 2.13% and 2.06% in 2012 and 2013,respectively,at 10–50 cm soil depths; （3） BGB had significant positive correlations with soil moisture at 100 cm depth and with soil temperature at 20–100 cm depths （P〈0.05） ,but the mean correlation coefficient of soil temperature was 0.354,greater than the 0.245 of soil moisture.R/S ratio had a significant negative correlation with soil temperature at 20 cm depth （P〈0.05） .The warmer soil temperatures in shallow layers increased the biomass allocation to above-ground plant parts,which leading to the increase in AGB;whereas the enhanced thawing of frozen soil in deep layers causing by warming treatment produced more moisture that affected plant biomass allocation.

Graphene oxide influences bacterial community and soil environments of Cd-polluted Haplic Cambisols in Northeast China

Graphene oxide(GO),a carbon nanomaterial that is widely used in the environment and other industries,may pose potential risks to ecosystems,especially the soil ecosystem.Some soils in Northeast China are frequently polluted with cadmium(Cd) metal.However,there is no study on the influence of GO on the Cd-contaminated soil microbial community and soil chemical properties.In this study,Cd(100 mg kg^(-1))-polluted soils were treated with different concentrations of GO(0,25,50,150,250,and 500 mg L^(-1),expressed as T1,T2,T3,T4,T5,and T6,respectively) for 40 days.The treatment without Cd pollution and GO served as the control(CK).Then,we investigated the influence of the GO concentrations on the bacterial community and chemical properties of Cd-polluted Haplic Cambisols,the zonal soil in Northeast China.After GO addition,the richness and diversity indexes of the bacterial community in Cd-contaminated Haplic Cambisols initially increased by 0.05-33.92% at 25 mg L^(-1),then decreased by0.07-2.37% at 50 mg L^(-1),and then increased by 0.01-24.37%within 500 mg L^(-1) again.The species and abundance of bacteria varied with GO concentration,and GO significantly increased bacterial growth at 25 and 250 mg L^(-1).GO treatments influenced the bacterial community structure,and the order of similarity of the bacterial community structure was as follows:T4=T5> T1=T6> T2> T3> CK.Proteobacteria and Acidobacteria were the dominant bacteria,accounting for 36.0% and 26.2%,respectively,of soil bacteria.Different GO treatments also significantly affected the metabolic function of bacteria and further influenced the diversity of the bacterial community structure by affecting several key soil chemical properties:soil pH,organic matter and available potassium,phosphorus,and cadmium.Our results provide a theoretical basis for scientific and comprehensive evaluation of the environmental impacts of GO on the zonal forest soils of Northeast China.

Progress of Mid Infrared Spectroscopy in Soil Environment Research

Soil is the basis of agricultural and forestry production,and it is of great significance to obtain soil information efficiently and comprehensively for soil management.Due to the complexity of soil organic components,it is difficult to obtain the information of soil organic components comprehensively by traditional chemical analysis method.As a non-destructive,real-time and high-throughput analysis method,mid infrared spectroscopy(MIR)has the ability to obtain soil organic environmental information efficiently and accurately.It can provide a large number of basic data for soil environmental monitoring,digital mapping,agricultural and forestry production,and help to realize the real-time monitoring of soil environment and the informatization of agriculture and forestry.In this paper,the detection process of MIR obtaining soil environmental spectral information and processing methods of spectral data were briefly introduced,and the research progress on extraction and influencing factors of mid infrared spectrum characteristics of soil in recent years was reviewed.Moreover,the significance and future development direction of soil science for the technology were discussed.

A Study on Rice Growth and Soil Environments in Paddy Fields Using Different Organic and Chemical Fertilizers

Currently, the majority of paddy fields in Japan are grown using chemical fertilizers and synthetic chemical pesticides, since chemical fertilizers can provide the nutrients necessary for plant growth. However, there are concerns regarding the environmental impact of chemical fertilizer and pesticides production, such as reduction of soil microorganisms and water pollution due to the runoff of fertilizer components from the soil caused by excessive fertilizer application. In this study, we investigated the effects of the application of organic and chemical fertilizers on the plant growth of paddy fields, in addition to their effects on the chemical and biological properties of the soil. The panicle numbers of rough and brown rice, the 1000-grain weight of the rough and brown rice, and the percentages of ripened grains were significantly higher in paddy soils grown with organic fertilizers than in those grown with chemical fertilizers. In addition, the total carbon (TC) contents and pH values were significantly higher in the soils of paddy fields grown with organic fertilizers. Furthermore, the soils of paddy fields grown with organic fertilizers exhibited greater bacterial biomasses, N circulation activity, and P circulation activity than the soils of paddy fields grown using chemical fertilizers, although the differences were not significant. In this study, the difference in plant growth was appeared in fertilizer application such as organic and chemical fertilizers. It was indicated that the organic fertilizer and pesticide reduction management increased the soil bacterial biomass and activated the material cycle such as N circulation activity.

Review and Reflection on the Development Process of Soil Environmental Quality Standards in China

In this paper,the development process of the construction of soil environmental quality standards in China is reviewed,and the construction situation of soil environmental quality standards in typical developed countries is introduced.According to characteristics of soil environment and practice of soil environment management in China,the relevant suggestions are discussed,thereby further perfecting construction work of soil environmental quality standards in China.

Review of Soil Environmental Contamination Caused by Heavy Metals from Electronic Wastes

The reports about soil environmental contamination from heavy metals in electronic wastes were reviewed. The production, sources and disposition of electronic wastes were introduced. The negative impacts of electronic wastes on the environment were analyzed, and soil pollution from electronic wastes in several typical districts were discussed and summarized.

Predicting the Bioaccessibility of Soil Cd,Pb,and As with Advanced Machine Learning for Continental-Scale Soil Environmental Criteria Determination in China

Investigating the bioaccessibility of harmful inorganic elements in soil is crucial for understanding their behavior in the environment and accurately assessing the environmental risks associated with soil.Traditional batch experimental methods and linear models,however,are time-consuming and often fall short in precisely quantifying bioaccessibility.In this study,using 937 data points gathered from 56 journal articles,we developed machine learning models for three harmful inorganic elements,namely,Cd,Pb,and As.After thorough analysis,the model optimized through a boosting ensemble strategy demonstrated the best performance,with an average R2 of 0.95 and an RMSE of 0.25.We further employed SHAP values in conjunction with quantitative analysis to identify the key features that influence bioaccessibility.By utilizing the developed integrated models,we carried out predictions for 3002 data points across China,clarifying the bioaccessibility of cadmium(Cd),lead(Pb),and arsenic(As)in the soils of various sites and constructed a comprehensive spatial distribution map of China using the inverse distance weighting(IDW)interpolation method.Based on these findings,we further derived the soil environmental standards for metallurgical sites in China.Our observations from the collected data indicate a reduction in the number of sites exceeding the standard levels for Cd,Pb,and As in mining/smelting sites from 5,58,and 14 to 1,24,and 7,respectively.This research offers a precise and scientific approach for cross-regional risk assessment at the continental scale and lays a solid foundation for soil environmental management.

Evaluation on Soil Heavy Metal Pollution of Agricultural Habitat Environment in Xi'an City

[Objective] This study aimed to understand and grasp the soil heavy metal pollution status of agricultural habitat environment in Xi＇an City. [Method] The soil heavy metal pollution status of pollution-free agricultural products-producing areas in 9 counties （districts） of Xi＇an City was investigated. A total of 609 soil samples were collected, and their Cd, Hg, As, Pb and Cr contents were determined. In addition, the heavy metal pollution status of the collected soil samples was evaluated by Nemerow index method. [Result] The pollution in Baqiao, Chang＇an; Gaoling, Lan- tian, Lintong and Yanliang was of grade I, belonging to clean level; the pollution in Hu County, Weiyang and Zhouzhi was of grade II, near the warning line, belong to relatively clean level. There was no large-area soil heavy metal pollution overall. The investigated areas could be used as production bases of pollution-free agricultural products and even high-quality agricultural products. However, the heavy met- als contents in some individual areas exceeded relevant soil environmental quality standards, and they should be avoided or forbidden during regional planning and selection of production area. [Conclusion] Soil heavy metal pollution of agricultural habitat environment in Xi＇an City is generally at good status. Targeting at the future development plan of Xi＇an City, feasible and scientific suggestions are put forward.

Assessment and mapping of environmental quality in agricultural soils of Zhejiang Province, China

Heavy metal concentrations in agricultural soils of Zhejiang Province were monitored to indicate the status of heavy metal contamination and assess environmental quality of agricultural soils. A total of 908 soil samples were collected from 38 counties in Zbejiang Province and eight heavy metal （Cd, Cr, Pb, Hg, Cu, Zn, Ni and As） concentrations had been evaluated in agricultural soil. It was found 775 samples were unpolluted and 133 samples were slightly polluted and more respectively, that is approximately 14.65% agricultural soil samples had the heavy metal concentration above the threshold level in this province by means of Nemerow＇s synthetical pollution index method according to the second grade of Standards for Soil Environmental Quality of China （GB15618- 1995）. Contamination of Cd was the highest, followed by Ni, As and Zn were lower correspondingly. Moreover, Inverse Distance Weighted （IDW） interpolation method was used to make an assessment map of soil environmental quality based on the Nemerow＇s pollution index and the soil environmental quality was categorized into five grades. Moreover, ten indices were calculated as input parameters for principal component analysis （PCA） and the principal components （PCs） were created to compare environmental quality of different soils and regions. The results revealed that environmental quality of tea soils was better than that of paddy soils, vegetable soils and fruit soils. This study indicated that GIS combined with multivariate statistical approaches proved to be effective and powerful tool in the mapping of soil contamination distribution and the assessment of soil environmental quality on provincial scale, which is beneficial to environmental protection and management decision-making by local government.

Effect of pH Value on Stress Corrosion Cracking of X70 Pipeline Steel in Acidic Soil Environment

The effect of pH value on the stress corrosion cracking （SCC） of API XT0 pipeline steel in simulated acidic soil solutions was investigated by using slow strain rate test, electrochemical polarization curves, electrochemical impedance spectroscopy, and scanning electron microscopy, pH plays an important role in the susceptibility and electrochemical mechanism of SCC. The pH higher than 5 has no significant effect on electrochemical processes. By contrast, the pH lower than 5 intensifies cathodic hydrogen evolution reactions, thus increasing the cathodic current and corrosion potential. Under different pH values, the SCC mechanism of XT0 pipeline steel varies among anodic dissolution （AD）, hydrogen embrittlement （HE）, and the combination of AD and HE （AD ＋ HE） with variations of applied potential. At -850 mVscE, the SCC mechanism is HE if pH is less than 4 or AD 4- HE if pH value is more positive.

Effects of water application intensity of micro-sprinkler irrigation and soil salinity on environment of coastal saline soils

To achieve the greatest leaching efficiency,water movement must occur under unsaturated flow conditions.Accordingly,the water application intensity of irrigation must be chosen carefully.The aim of this study was to evaluate the impact of the water application intensity of micro-sprinkler irrigation on coastal saline soil with different salt contents.To achieve this objective,a laboratory experiment was conducted with three soil salinity treatments(2.26,10.13,and 22.29 dS/m)and three water application intensity treatments(3.05,5.19,and 7.23 mm/h).The results showed that the effect of soil salinity on soil water content,electrical conductivity,and pH was significant,and the effect of the water application intensity was insignificant.High soil water content was present in the 40e60 cm profile in all soil salinity treatments,and the content was higher in the medium and high water application intensity treatments than in the low-intensity treatment.Significant salt leaching occurred in all treatments,and the effect was stronger in the high soil salinity treatment and medium water application intensity treatment.In the medium and high soil salinity treatments,pH exhibited a decreasing trend,with no trend change in the low soil salinity treatment,and the pH value was higher in the medium water application intensity treatment than in the other two treatments.These results indicated that the three intensities evaluated had no statistically different effect on the electrical conductivity of saturated soil-paste extracts(EC)in the upper 20 cm of the soil profile,and it would be better to maintain a lower value of the water application intensity.

Automatic extraction and structuration of soil–environment relationship information from soil survey reports

In addition to soil samples, conventional soil maps, and experienced soil surveyors, text about soils(e.g., soil survey reports) is an important potential data source for extracting soil–environment relationships. Considering that the words describing soil–environment relationships are often mixed with unrelated words, the first step is to extract the needed words and organize them in a structured way. This paper applies natural language processing(NLP) techniques to automatically extract and structure information from soil survey reports regarding soil–environment relationships. The method includes two steps:(1) construction of a knowledge frame and(2) information extraction using either a rule-based method or a statistic-based method for different types of information. For uniformly written text information, the rule-based approach was used to extract information. These types of variables include slope, elevation, accumulated temperature, annual mean temperature, annual precipitation, and frost-free period. For information contained in text written in diverse styles, the statistic-based method was adopted. These types of variables include landform and parent material. The soil species of China soil survey reports were selected as the experimental dataset. Precision(P), recall(R), and F1-measure(F1) were used to evaluate the performances of the method. For the rule-based method, the P values were 1, the R values were above 92%, and the F1 values were above 96% for all the involved variables. For the method based on the conditional random fields(CRFs), the P, R and F1 values for the parent material were, respectively, 84.15, 83.13, and 83.64%; the values for landform were 88.33, 76.81, and 82.17%, respectively. To explore the impact of text types on the performance of the CRFs-based method, CRFs models were trained and validated separately by the descriptive texts of soil types and typical profiles. For parent material, the maximum F1 value for the descriptive text of soil types was 90.7%, while the maximum F1 value for the descriptive text of soil profiles was only 75%. For landform, the maximum F1 value for the descriptive text of soil types was 85.33%, which was similar to that of the descriptive text of soil profiles(i.e., 85.71%). These results suggest that NLP techniques are effective for the extraction and structuration of soil–environment relationship information from a text data source.

Adsorption behavior of antibiotic in soil environment： a critical review

Antibiotics are used widely in human and veterinary medicine, and are ubiquitous in environment matrices worldwide. Due to their consumption, excretion, and persistence, antibiotics are disseminated mostly via direct and indirect emissions such as excrements, sewage irrigation, and sludge compost and enter the soil and impact negatively the natural ecosystem of soil. Most antibiotics are amphiphilic or amphoteric and ionize. A non-polar core combined with polar functional moieties makes up numerous antibiotic molecules. Because of various molecule structures, physicochemical properties vary widely among antibiotic compounds. Sorption is an important process for the environment behaviors and fate of antibiotics in soil environment. The adsorption process has decisive role for the environmental behaviors and the ultimate fates of antibiotics in soil. Multiply physicochem- ical properties of antibiotics induce the large variations of their adsorption behaviors. In addition, factors of soil environment such as the pH, ionic strength, metal ions, and organic matter content also strongly impact the adsorption processes of antibiotics. Review about adsorption of antibiotics on soil can provide a fresh insight into understanding the antibiotic-soil interactions. Therefore, literatures about the adsorption mechanisms of antibiotics in soil environment and the effects of environment factors on adsorption behaviors of antibiotics in soil are reviewed and discussed systematically in this review.

Updating conventional soil maps by mining soil–environment relationships from individual soil polygons

Conventional soil maps contain valuable knowledge on soil–environment relationships.Such knowledge can be extracted for use when updating conventional soil maps with improved environmental data.Existing methods take all polygons of the same map unit on a map as a whole to extract the soil–environment relationship.Such approach ignores the difference in the environmental conditions represented by individual soil polygons of the same map unit.This paper proposes a method of mining soil–environment relationships from individual soil polygons to update conventional soil maps.The proposed method consists of three major steps.Firstly,the soil–environment relationships represented by each individual polygon on a conventional soil map are extracted in the form of frequency distribution curves for the involved environmental covariates.Secondly,for each environmental covariate,these frequency distribution curves from individual polygons of the same soil map unit are synthesized to form the overall soil–environment relationship for that soil map unit across the mapped area.And lastly,the extracted soil–environment relationships are applied to updating the conventional soil map with new,improved environmental data by adopting a soil land inference model(SoLIM)framework.This study applied the proposed method to updating a conventional soil map of the Raffelson watershed in La Crosse County,Wisconsin,United States.The result from the proposed method was compared with that from the previous method of taking all polygons within the same soil map unit on a map as a whole.Evaluation results with independent soil samples showed that the proposed method exhibited better performance and produced higher accuracy.

Effect of Phopshate Fertilizer and Manure on Crop Yield, Soil P Accumulation, and the Environmental Risk Assessment

Phosphorus （P） applied from fertilizer and manure is important in increasing crop yield and soil fertility; however, excessive uses of phosphate fertilizer and manure may also increase P loss from agricultural soils, posing environmental impact. A long term experiment was conducted on a calcareous soil （meadow cinnamon） in Hebei Province, China, from 2003 to 2006 to investigate the effects of phosphate fertilizer and manure on the yield of Chinese cabbage, soil P accumulation, P sorption saturation, soluble P in runoff water, and P leaching. P fertilizer （P2O5） application at a rate of 360 kg ha^-1 or manure of 150 t ha^-1 significantly increased Chinese cabbage yield as compared to the unfertilized control. However, no significant yield response was found with excessive phosphate or manure application. Soil Olsen-P, soluble P, bioavailable P, the degree of phosphorus sorption saturation in top soil layer （0-20 cm）, and soluble P in runoff water increased significantly with the increase of phosphate fertilizer and manure application rates, whereas the maximum phosphorus sorption capacity （Qm） decreased with the phosphate fertilizer and manure application rates. Soil Olsen-P and soluble P also increased significantly in the sub soil layer （20-40 cm） with the high P fertilizer and manure rates. It indicates that excessive P application over crop demand can lead to a high environmental risk owing to the enrichment of soil Olsen-P, soluble P, bioavailable P, and the degree of phosphorus sorption saturation in agricultural soils.